By Jason Watson, CPA
Posted Sunday, March 22, 2026

While bonus depreciation usually grabs the headlines, IRC Section 179 is the workhorse of small-to-mid-sized real estate. For rental properties under $5M, cost segregation typically identifies 20% to 40% of the basis as eligible property (5-, 7-, or 15-year assets). Since the Section 179 limit is $2,560,000 for the 2026 tax year, it effectively covers the entire amount of property eligible for acceleration (and perhaps even higher than a $5M purchase).

The critical distinction is intent:

• Bonus Depreciation is an automatic loss generator. It can drive your business income into the negative, creating a Net Operating Loss (NOL) that can offset your W-2 income, subject to excess business loss limitations (EBL) and other restrictions.
• Section 179 is an elective profit killer. It is limited by your taxable income, which can restrict how much you can use in a given year. This makes it feel weaker federally, but far more powerful at the state level. And No, you don’t have to wait long for us to explain.

The State Conformity Battleground

This is where Section 179 shines. Most states are decoupled from bonus depreciation- meaning if you take a $500,000 bonus deduction on that massive cost segregation study on that equally massive rental property, your state makes you add it back (literally or figuratively depending on your state) and pay state tax on it today. However, a significant majority of states conform to federal Section 179 limits.

Sidebar: As of the 2026 tax year, these states generally roll with the federal Section 179 limits as of the 2026 tax year- AL, AZ, CO, DE, GA, ID, IA, IL, KS, LA, MA, ME, MI, MS, MO, MT, NE, NM, ND, NY, OK, OR, RI, SC, UT, VT, VA, WV. There are some developments with AZ.

Sidebar #2: Some states have detachment anxiety but eventually compromise. California is the poster child—capping Section 179 at $25,000 and forcing a second depreciation schedule. Other states such as Arkansas, Hawaii, Indiana, Kentucky, New Jersey, and Pennsylvania also limit or modify Section 179 in various ways rather than fully conforming. Ohio allows Section 179 but requires adjustments that effectively spread the benefit over time. Maryland also imposes limits with additional modifications. Translation: same concept, different flavors of pain.

By using Section 179 instead of bonus depreciation, you achieve tax nirvana: a massive deduction that works for both federal and state tax returns simultaneously. Without 179, you might save 37% federally but still get nickeled and dimed by a 5% to 9% state tax on that same income. More like beaten with the dollars whip- forget about nickels and dimes!

Trapped Section 179 Deductions

Despite its state-level benefits, Section 179 has a locking mechanism when used inside a pass-through entity such as a multi-member LLC (MMLLC) taxed as a partnership. While the partnership allocates Section 179 deductions through the K-1, the deduction is first limited at the entity level based on the partnership’s business income. It is then subject to additional limitations at the partner level under IRC Section 179(b)(3), along with basis, at-risk, and passive activity rules.

If the partnership does not have sufficient income, a portion of the Section 179 deduction never makes it to your personal tax return in the first place. And if it doesn’t land on your Form 1040, it cannot offset anything including your W-2 income. Yeah, read that again. Buzzkill for sure.

As a result, even if the partnership generates a large Section 179 deduction, a partner with limited income might find the deduction effectively trapped, either at the entity level or on their personal return, and carried forward to future years. Possibly a lot of future years.

Sidebar: Think you can avoid a partnership return by assigning your LLC interests to a joint revocable trust? Think again. In common law states, the IRS disregards the trust and sees two distinct owners (the spouses) under IRC Sections 671–679, mandating a Form 1065 partnership filing per Treasury Regulations Section 301.7701-3. Unless you are in a community property state, you cannot bypass the partnership layer or report this activity directly on your Form 1040.

Bonus depreciation asks, “Did you place it in service?” Section 179 asks, “Do you have enough income to deserve it?” Yeah, Ok, animals can’t talk, we get it, but play along please.

Change in Use Clawback

Section 179 carries a “predominant use” sting that bonus depreciation (for non-listed property) largely avoids.

• Section 179 Recapture: If you convert your STR into a second home or primary residence, and as such business use drops below 50%, the IRS triggers an immediate recapture. You must pay back the benefit (the difference between the 179 deduction and standard MACRS depreciation) as ordinary income in the year of conversion. Yuck.
• Bonus Recapture: For IRC Section 1245 property (furniture, carpet, etc.), there is generally no immediate clawback just for taking down your Airbnb listing. The depreciation simply sits on the inactive activity’s depreciation schedule until you sell the property.

Granted, this is crystal ball type stuff. Then again, if 3-4 years go by, and then you want to take the short-term rental out of service and make it a second home, the decision you made way back when could haunt you.

The OBBBA Acquired Provision

The OBBBA introduced a specific hurdle for bonus depreciation- the “Acquired after January 19, 2025” rule. To qualify for 100% bonus depreciation, you must have acquired the property after that date.

If you bought a home in 2024 as a primary residence and are converting it to a rental in 2026, it was acquired prior to the OBBBA deadline. In this specific “primary-to-rental” conversion, bonus depreciation will be subject to pre-OBBBA rules or in this case 40%. Section 179 does not have this same “acquired” restriction, making it the primary viable path for a massive year-one deduction on older properties newly placed into service as rentals.

Section 179 Versus Bonus Depreciation Wrap-Up

Section 179 is the Swiss army knife of depreciation- it’s the best way to get a state-level deduction and the only way to handle properties acquired before the OBBBA. Its only real downsides are its inability to create a paper loss at the entity level and the aggressive recapture rules if you decide to move in.

Said differently- the question isn’t which deduction is bigger but rather which one survives all the limitations and rules, today and tomorrow. Yeah, Ok, that probably didn’t help much.

Let’s talk about mid-year conversions. What happens if you run a short-term rental (STR) for the first four months of the year, convert it to a long-term rental (LTR) for the remaining eight months, successfully treat them as two separate economic units on your tax return under Treasury Regulations Section 1.469-4(c), and then decide to do a cost segregation study?

Do you take the massive bonus depreciation deduction and slice it up by allocating 4/12ths to the STR and 8/12ths to the LTR?

No. You do not. And understanding exactly why is the difference between a massive tax refund and a massive tax trap. Oh, let’s not forget an incorrect tax return as well.

The Point-in-Time Rule

Bonus depreciation is not a monthly, prorated concept. It is a point-in-time deduction. It drops like an anvil the exact moment the property (or its cost-segregated components) is first placed in service for a business use.

Standard MACRS depreciation is prorated based on the applicable depreciation conventions and the portion of the year each activity operated, but bonus depreciation is claimed in full by whatever activity is happening on day one. Because of this, the order in which you operate the property dictates exactly which bucket that giant tax loss lands in.

STR First, Then LTR (The Winner)

Let’s say you place the rental property in service as an STR in January. You materially participate, manage the guests, and satisfy the 7-day rule. Do all the right things.

In May, you get tired of the turnover, or perhaps ski season is closing out, and lease it to a long-term tenant. Because it was an STR when it was first placed in service, the STR activity claims the entirety of the bonus depreciation. Assuming you materially participated, this creates a massive non-passive loss that can offset your W-2 or business income.

When the property converts to an LTR in May, it inherits the remaining, much lower adjusted basis. The LTR activity simply claims the standard, prorated MACRS depreciation on the leftovers for the remaining eight months.

Mechanically, there are a couple of things to keep in mind. First, you will list two activities on your tax return- one for the STR version and another for LTR version of the same actual real estate asset. Next, you will have two depreciation schedules as well, and the LTR’s unadjusted cost basis will be the STR’s original cost basis less whatever depreciation including bonus depreciation was deducted on that activity.

LTR First, Then STR (The Trap)

Now, let’s flip it. You place the property in service as an LTR in January. In May, the tenant moves out, and you decide to turn it into an Airbnb to hit the juicy summer travel traffic. You do a cost segregation study since now it qualifies as an STR and can deduct against your big W-2 income.

Because it was an LTR when it was first placed in service, the LTR activity claims the bonus depreciation. Unless you are a qualifying Real Estate Professional (REPS) or have other passive income, that massive cost segregation and subsequent depreciation loss drops straight into your passive bucket and gets trapped. Yuck.

When you convert to an STR in May, you might materially participate and run a great hospitality business, but the depreciation damage is done. Just like our other example, the STR activity only inherits the remaining adjusted basis and gets a tiny sliver of standard MACRS depreciation. The giant STR loss bomb you were hoping to trigger was already detonated in the passive bucket. Ok, that was a bit over the top, but whatever.

The Takeaway

If you are treating a mid-year conversion as two separate activities, there is no magic rule that lets you assign the bonus depreciation to the activity you prefer. It is strictly dictated by the placed-in-service date.

If your strategic intent is to use the STR loophole to offset ordinary income, the property must be placed in service as an STR first. Flipping an LTR to an STR mid-year mechanically works the same way, but strategically, it traps your best tax deductions behind the passive loss wall. Timing isn’t just everything; it is the only thing.

The Reboot Myth And The Entity Shuffle

Some clever real estate investor is inevitably going to ask: “Wait, if an STR is a totally different business than an LTR, why can’t I just take the LTR out of service, and then ‘re-place’ it into service a week later as a brand-new STR to grab the bonus depreciation again? Or better yet, what if I sell it to a new multi-member LLC I own with my spouse so a ‘new taxpayer’ buys it?”

Nice try, but the IRS saw you coming a mile away. You cannot unplug your rental property and plug it in somewhere else and reboot your tax deductions. Here is why the tax code crushes both of these maneuvers:

Under IRC Section 168(k), bonus depreciation is strictly a “first placed in service” deduction. The IRS only cares about the very first time you made that specific asset ready for any income-producing activity. Transitioning from an LTR to an STR is classified as a “Change in Use” under Treasury Regulation Section 1.168(i)-4. It may change how the property is classified for depreciation purposes, but it does not reset the original placed-in-service date.

Sidebar: The one exception? Brand-new assets you buy specifically for the STR, like a hot tub or new furniture. Those get their own fresh placed-in-service date and their own bonus depreciation. Yeah, this doesn’t make you feel any better.

If you try to outsmart the system by dropping the property into a new LLC with your spouse or your S Corp, you hit two brick walls:

• If you simply contribute the property to the new LLC, the entity “steps into your shoes” as suggested by IRC Section 168(i)(7). It inherits your exact depreciation schedule, remaining basis, and original placed-in-service date.
• If you actually sell the property to the LLC to claim bonus depreciation on “new to the LLC” property, you trigger related party transaction rules. Because you, your spouse, or your controlled entities own more than 50% of the new entity, the IRS disallows the bonus depreciation entirely, and you just triggered a taxable sale for absolutely no reason.

Here is the exact language of IRC Section 168(i)(7) which will completely put you to sleep:

(7) Treatment of certain transferees
(A) In general
In the case of any property transferred in a transaction described in subparagraph (B), the transferee shall be treated as the transferor for purposes of computing the depreciation deduction determined under this section with respect to so much of the basis in the hands of the transferee as does not exceed the adjusted basis in the hands of the transferor.

The house always wins. The asset keeps its original history, and the bonus depreciation clock does not reset.

By Jason Watson, CPA
Posted Sunday, March, 22, 2026

There are a handful of big pitfalls and a few gotchas.

Passive Activity Loss (PAL) Limits

If you are considering a cost segregation study on a rental property, and that activity is considered a passive activity, your tax deduction is limited to $25,000 (passive loss limit). If you earn over $150,000 as a household, your tax deduction might be limited to $0. Yes, you are reading that zero correctly. We discuss passive activity loss limitations later on page xx.

There are two ways to get around this. First, if you qualify as a real estate professional, then your passive activity loss limits go away. To be a real estate professional as defined by the IRS and not what you hear at the bar, an individual must spend more than half of the personal services performed in all businesses and activities during the year in real estate activities. As a reminder, this includes the following-

real property development, redevelopment, construction, reconstruction, acquisition, conversion, rental, operation, management, leasing, or brokerage trade or business.

Read this again! If you have another full-time job in which you work 40 hours a week, you will need to work more than 40 hours per week in your real estate business and related activities. Having a W-2 is a red flag, as they say, straight out of the Passive Activities Loss Audit Techniques Guide (ATG) from the IRS.

Next, your hours worked in real estate activities must be more than 750 hours. Any work performed as an investor cannot be counted. There are a bunch of other devils in the details. Yes, most real estate agents qualify, not because they are real estate agents but rather time spent on real estate activities.

Finally, you must materially participate as defined by the IRS in each rental activity. We dive deep into real estate professional or REP status or just “REPS” as the cool kids say in a later section.

The other way to get around the passive loss limits is to have the activity not be considered passive. Makes sense right? Let’s just pencil-whip this activity and add the word “non-“ in front of it all. Done!

To be a nonpassive activity, the average stay in the rental must be 7 days or less. Your typical VRBO Airbnb situation. However, you must also materially participate (there’s that darn word again) in the activity. Alternatively, for average stays of 30 days or less, you provide hotel-like services like changing linens during the stay or providing tours (think hunting lodge).

These two situations are considered nonpassive activities and losses are not limited. As a small sidebar, or perhaps a minibar, the first example is reported on Schedule E, and the second is on Schedule C possibly subject to self-employment taxes.

If PAL Limited Must Have Net Rental Income

If you can’t escape the passive activity loss limits, then you must have net rental income from the rental property or from other properties or real estate investments to absorb the accelerated depreciation expense and grab that accelerated cash flow. Self-rentals, where you own the building and lease it back to your business, do not usually absorb passive losses from other rentals. We talk about self-rentals later.

Depreciation Recapture Can Bite

Recall that depreciation is a tax deferral. When you sell the property, you have depreciation recapture which simply means you must pay back the deferred taxes. There is some tax arbitrage here, however, since recapture is limited to a 25% tax rate on Section 1250 property (remember our mini chat about this) where you might have deducted depreciation at a 37% marginal tax rate. You can also escape this gotcha with a Section 1031 Like-Kind Exchange.

Sidebar: Recall that Section 1245 property, which might be “created” with a cost segregation report, is recaptured at ordinary income tax rates. We stated that earlier. However, the intersection of Section 1031 and Section 1245 can be problematic since you cannot like-kind exchange Section 1245 property. As such, you can perform a pretty Section 1031 Like-Kind Exchange, and still have a tax bill because of the sale of Section 1245 property in connection with the overall rental property sale.

Cash Flow Juice Worth Cost Seg Squeeze

The cost of the report or cost segregation study must be significantly lower than the improved time-value of the accelerated cash flow. In other words, the juice must be worth the squeeze, including the audit risk.

Another way to look at this gotcha- accelerated depreciation is not extra depreciation. Two rentals, one with a cost segregation study and one without, will be fully depreciated at 27.5 years. As such, it is purely a time-value of money compared to fee consideration. Then again, if you take the tax savings (deferral in reality) and blast off on a fun vacation, that has value too, right?

Cost Segregation Is A One And Done Event

Another gotcha is one that is often overlooked. A cost segregation study and the subsequent big depreciation deduction is a one and done event. The following tax year, your depreciation comes down to earth and is actually less than it would normally be. Keep mind that cost segregation accelerates depreciation; it does not create new or phantom depreciation. Take a $780,000 building that would normally depreciate $20,000 per year. If you accelerate $150,000 in depreciation the first year, years 2 through 39 will be $16,600ish (versus $20,000).

The Excess Business Loss (EBL) Trap

Generating a large tax loss through cost segregation is only a victory if you can actually use it to offset income in the current year. Under IRC Section 461(l), the tax code imposes a cap on Excess Business Losses (EBL) that can offset non-business income such as W-2 wages.

The EBL rule is the final gatekeeper in a long chain of loss limitations. Your losses must first survive basis limits, the at-risk rules, and the passive activity rules before they even reach the EBL calculation.

The One Big Beautiful Bill Act (OBBBA) made the EBL limitation permanent and reset the inflation adjustment base year. The statute lists a baseline threshold of $512,000 for married filing jointly ($256,000 single), but taxpayers use the inflation-adjusted amount published annually by the IRS. For example, the 2025 threshold for joint filers is $626,000, while beginning in 2026 the indexing reset pushes the limit back closer to the statutory baseline.

Confusion aside, if your combined business and rental losses exceed the annual threshold of roughly $256,000 single or $512,000 joint starting in 2026 the excess cannot offset non-business income that year.

Instead, the excess becomes a Net Operating Loss (NOL) carryforward. That loss is not lost, but it is delayed and the delay can be painful. Imagine generating a $1.5 million loss from a single cost segregation study or several smaller cost studies in one year expecting to wipe out your W-2 income, only to find a large portion locked away for future years.

And NOLs are not pure gold. They are calculated without regard to the standard deduction and generally can offset only 80% of taxable income in future years. In other words, even with a large NOL carryforward, you will likely still pay some tax.

The key is to plan. Two options- spread multiple cost segregation studies out across multiple years (yes, a Form 3115 with an IRC Section 481(a) adjustment is likely). Alternatively, opt out of certain asset classes for bonus depreciation such as 5-year.

EBL huh? Perhaps EBK as in excessive buzz kill. Or is buzzkill one word?

The Reverse Marginal Tax Bracket Pitfall

There is a common, yet flawed, mentality that “more deduction is always better,” but smart tax planning requires looking at the value of each deducted dollar. Depreciation is a cashflow play, but as your taxable income decreases, your marginal tax bracket decreases as well from 37% to 35%, down to 32%, and possibly even into the 12% range. Good? Maybe not.

In other words, your last dollar of tax deduction has way less pizzazz than your first.

If you perform cost segregation studies on several properties in a single year, you might successfully drive your taxable income down so severely that the tax dollars you deducted at the 12% level provide significantly less bang for your buck than those at the 37% level. This can hurt the cash flow ROI of cost segregation.

Going from $2M in taxable income down to $1.5M? Sure, that makes sense. Going from $700,000 down to $200,000 might still make sense, just not as much cents.

In many cases, it is far more efficient to spread your cost segregation studies over multiple years utilizing a Form 3115 / 481(a) adjustment (as mentioned just a bit ago) when necessary to ensure you are primarily offsetting income at your highest marginal rates. Before you go all-in, let’s do some tax planning to ensure the position is impactful. It is better to save 37 cents on the dollar next year than 12 cents on the dollar today. Even in Canada.

Tangible Personal Property Reporting

This really isn’t a big gotcha or pitfall, but as we discussed in our chapter on short-term rentals, many counties want you to report and pay tax on tangible personal property. While a cost seg study’s only job is to parse property away from typical real property and relabel it as personal property, not all personal property identified in your report is suddenly tangible personal property.

Conversely, many counties are similar to Florida’s 192.001(11)(d) which reads-

“Tangible personal property” means all goods, chattels, and other articles of value (but does not include the vehicular items enumerated in s. 1(b), Art. VII of the State Constitution and elsewhere defined) capable of manual possession and whose chief value is intrinsic to the article itself.

What does this mean? It means that tangible personal property for the sake of county taxes must have value by itself and be capable of manual possession. For example, certain components might be identified as IRC Section 1245 personal property, but their value is tied to the fact they are part of a larger building system. Carpet is a good example since it typically does not have material resale value. Specialized wiring for a restaurant kitchen is likely personal property eligible for Section 179 expensing and bonus depreciation, but is unlikely to be considered capable of manual possession with intrinsic value, and therefore not be tangible personal property by a county assessor.

By Jason Watson, CPA
Posted Sunday, March 22, 2026

Is there more to a cost segregation study? Yes, there is! So, we have two look-back cost segregation situations-

• You do a cost segregation study in 2024 and would like to “catch up” depreciation that was not taken on previous tax returns.

• You do a cost segregation study in 2024 for a prior year (let’s say 2021) and would like to apply accelerated depreciation to that year with a tax return amendment.

What’s the difference between a look-back cost segregation study and retroactive cost segregation study? Probably not much, but we’ll split some hairs. Let’s consider a retroactive study to be one where you are wanting to restate depreciation on a prior year tax return. Next, a look-back study is where you are wanting to catch-up depreciation in the current year. The IRS references look-back in their IRS Publication 5653 Cost Segregation Audit Techniques Guide (ATG).

Cost Segregation Examples

Why would you want to pick the second option above (the amendment or retroactive option)? Perhaps your income was sky high in 2023 and that big marginal tax bracket could use a little dent. Perhaps that was the only year you qualified as a real estate professional or could use the short-term rental loophole, and you just discovered this thing called cost segregation and accelerated depreciation, but your rental property is now long-term.

What if it is 2026, and you purchased a rental property in 2020. Assuming you could deduct the depreciation expense to create a reduction in taxable income, you would be unable to claim the refund because of the 3-year claim for refund statute of limitations. 2020 tax returns were due in 2021. 2021 plus 3 years is 2024. So, this would be silly, right? You are likely forced to use look-back.

Same situation as above, but you perform a retroactive cost segregation study for the 2023 tax year including the tax return amendment. Now we are cooking with gas (maybe). 2023’s tax returns were due April 15, 2024, so you have until April 15, 2027, to claim a refund, or October 15, 2027, if you extended your tax returns. You also have some housekeeping concerns in 2024 and 2025 since the depreciation taken would now be incorrect based on the new depreciable basis going forward from the 2023 amended tax return. Housekeeping is a nice way of saying tax return amendments are probable.

What if you don’t feel like amending your 2023 tax returns? Perhaps you believe amendments increase audit risk (spoiler alert, they don’t)? Perhaps you don’t like the 2024 and 2025 housekeeping problems with depreciation. Better yet, perhaps 2026 is a much higher income year, and a big old depreciation deduction sounds tasty. What can be done? By using Form 3115 Application for Change in Accounting Method with an IRC Section 481(a) adjustment, you can take advantage of 2023’s bonus depreciation in 2026.

Read that again! You are allowed to apply the 100% bonus depreciation rate associated with the 2021 placed-in-service year on your 2024 tax return where bonus depreciation is a lowly 60%. There are more mathematical gymnastics since the property eligible for bonus depreciation has been partially depreciated. Also, if you opted out of bonus depreciation in the past, this becomes problematic.

Sidebar: Many states do not follow the federal bonus depreciation rules. States such as California, New York, New Jersey and Hawaii require taxpayers to add back bonus depreciation and recover it over several years. This means a large federal deduction may create little or no immediate state tax benefit.

Another option is to not take bonus depreciation. Rather, you take the accumulated accelerated depreciation for 2023, 2024 and 2025 plus 2026 on your 2026 tax returns. This is an acceleration in a sense since you are carving out 5-year property (for example), but taking most (80%, 4 out of 5 years) from the back end of the depreciation schedule on today’s tax return.

Keep in mind that you can elect out of bonus depreciation for certain classes of property. In the example above, you could opt-out for 5-year property since you mostly don’t need it, and retain bonus depreciation for 7-year and 15-year property.

Look-Back Cost Segregation Mechanics

Ok, we’ve tossed around some terms like Form 3115 and IRC Section 481(a). What’s the difference, and how are they used together?

Form 3115 Application for Change in Accounting Method is used to request permission from the IRS for a change in an accounting method (such as cash to accrual) including changes to your depreciation accounting method. Specifically, if you’ve been historically depreciating a 5-year asset over 39.0 years, and you now want to accelerate depreciation, you need permission from the IRS.

Since this request is mostly rubber-stamped by the IRS, you then use IRC Section 481(a) to adjust depreciation to the correct number on your tax returns. In other words, this adjustment is more of a do-over or mulligan where you say, “had we depreciated correctly from the beginning, it would be this new number here that we conveniently want to deduct today.”

Quick summary- Form 3115 asks for permission to change and IRC Section 481(a) states that proper taxable income computation requires omitted or duplicate depreciation amounts to be accounted for. What is the IRC Section 481(a) adjustment thing? Here is the code-

A few options to summarize-

• Amend the prior year tax return since income was significantly higher that year, or you can only support real estate professional status or short-term rental loophole that year.

• Use Form 3115 plus the IRC Section 481(a) catch-up on today’s tax return which conveniently has two options- use bonus depreciation or elect out of bonus depreciation.

As you can see, there is a nice tax planning opportunity here and perhaps even some tax arbitrage given income fluctuations. Keep in mind that generally you will be going back to the in-service date of the rental property (ready and available for occupancy, and held out for rental use through advertising and related efforts) to calculate the amount of depreciation that should have been taken (accumulated) between then and now.

Could you file Form 3115 but not use IRC Section 481(a) to adjust depreciation? Yes. Maybe. Kinda rare. Sure, there is a world where you want (need) to change depreciation today for the future, and do not need or perhaps you are not eligible for a look-back catch-up adjustment.

Sidebar: Changing from 27.5 to 39.0 years for depreciation, or vise-versa, does not require filing Form 3115. A change in computing the depreciation allowance in the year of change for property is not a change in method of accounting according to Treasury Regulations Section 1.168(i)-4(f). Who knew? See our section on switching depreciation for more information.

The Ultimate Tax Arbitrage (Passive to Non-Passive)

Let’s look at a sexy piece of tax arbitrage using a look-back study and Form 3115. What happens if the character of your rental property changes?

Imagine you purchase a rental property in 2022. For 2022, 2023, and 2024, it operates as a traditional long-term rental. Because you have a day job with high income and you are not a real estate professional, any losses generated by the property are suspended due to passive activity loss limitations. Doing a cost segregation study during those years wouldn’t provide immediate tax relief; it would just build up a larger bucket of suspended passive losses.

But in 2025, the long-term tenant moves out. You furnish the property and pivot to a short-term rental. In 2026, you manage it yourself, keeping the average stay to 7 days or less and meeting the 100-hour material participation test (or any of the 7 tests). Suddenly, your rental qualifies for the short-term rental loophole, meaning the activity is now non-passive.

Here is where the tax arbitrage happens. In 2026, you commission a cost segregation study going back to the 2022 purchase date. You file Form 3115 with your 2026 tax return to claim the missed depreciation which also happens to include 100% bonus depreciation from 2022.

Because the IRC Section 481(a) adjustment is deducted entirely in the year of the accounting method change, the passive or non-passive character of the deduction is determined based on the activity’s status in that year per IRC Section 469. Since 2026 is the year of change, and the property is non-passive in 2026, the entire catch-up depreciation deduction is treated as non-passive.

The tax law does not track the passive character of the underlying years when a Section 481(a) adjustment is taken. It simply treats the entire adjustment as a deduction in the year of change.

Boom! You just pulled massive deductions from passive years where they were trapped, and dropped them directly onto your current year tax return to offset your W-2 or active business income. No amendments required, no passive loss limitations, and you capture 2021’s 100% bonus depreciation rate in a year when the current rate is much lower.

Sidebar: The One Big Beautiful Bill Act restored 100% bonus depreciation, Yes, but only for rental properties acquired and placed into service after January 19, 2025. It does not retroactive fix previous years such as 2024 and 2023 when bonus was less than 100%.

The big takeaway with all this is- The bonus depreciation percentage is based on when the rental property was acquired and placed into service, and not when the cost segregation study is performed or when Form 3115 is filed!

Look-Back Cost Segregation Study For 1 Year

What about going back just one year? You purchase a rental property in 2023 and naturally start depreciating it using conventional methods. You learn about cost segregation in 2024 after filed your 2023 tax returns. Now what? Are you hosed because you technically have not established an accounting method yet (spoiler alert, you need two years)? Nope.

The short answer is the one above- File Form 3115 Application for Change in Accounting Method and apply an IRC Section 481(a) adjustment. But there is a technical difference that most tax professionals are unaware of. To request a change in accounting method (in this case, for depreciation) you normally need to have at least two years of using an accounting method to have an established method. If you have only depreciated the rental property on one tax return, you do not have the requisite two years necessary to apply for a change in accounting method. As such, your only recourse is (was) to amend your tax returns to deduct the unclaimed depreciation. Yuck.

However, according to the 447 pages found in IRS Revenue Procedure 2024-23 (pages 38-39 to be exact),

(b) Taxpayer has not adopted a method of accounting for the item of property. If a taxpayer does not satisfy section 6.01(1)(a)(i) of this revenue procedure … because this item of property is placed in service by the taxpayer in the taxable year immediately preceding the year of change the taxpayer may change from the impermissible method of determining depreciation to the permissible method of determining depreciation for the 1-year depreciable property by filing a Form 3115 for this change, … Alternatively, the taxpayer may change from the impermissible method of determining depreciation to the permissible method of determining depreciation for a 1-year depreciable property by filing an amended federal income tax return.

Tilt! To put into simple terms- there is an exception for year 2 where you can apply for a change in accounting method without technically establishing a chosen method to change.

Sure, in the example above, you are stuck with 80% bonus depreciation for 2023, but depending on your income, that might still be a meaningful deduction.

Opted Out of Bonus Depreciation Revisited

As we mentioned in a previous section, bonus depreciation election is assumed. If you elect to opt-out of bonus depreciation for some reason (and there are some narrow ones), you can revoke the election to opt out which is like a triple negative. How about this? You can amend your tax returns to claim and deduct bonus depreciation under IRS Revenue Procedure 2020-50.

This is generally good news but here is the bad news- a taxpayer who opted out may revoke that election by filing an amended return only if-

• the initial election to opt out was made on a timely filed tax return, and

• the amended tax return is filed within six months (excluding extensions) of the original tax return’s due date.

Yuck! However, there might be relief by making a request using Form 3115 Application for Change in Accounting Method. More discussion is likely required with your cost segregation buddies at WCG CPAs & Advisors.

Form 3115 does not technically revoke the prior election to opt out of bonus depreciation. Instead, it asks the IRS for permission to change the taxpayer’s depreciation method. If approved, the taxpayer adopts the new method going forward and adjusts prior depreciation through the IRC Section 481(a) catch-up adjustment, which can allow the depreciation that should have been taken in earlier years to be deducted in the current year.

Retroactive Cost Segregation Summary

Bonus depreciation is determined by when the property was placed in service, not when or how you claim the deduction. In other words, if bonus is 100% today (play along), but 60% when you placed the rental into service (for the 2024 tax year), you are stuck with 60%. Here is another summary in table format-

Service Year	Cost Seg	Amend	3115	481(a)	Bonus Taken
2022	Look Back	No	Yes	Yes	100%, Required*
2022	Retroactive	Yes	NA	NA	100%, Optional
2023	Look Back	No	Yes	Yes	80%, Required*
2023	Retroactive	Yes	NA	NA	80%, Optional
2024	Look Back	No	Yes	Yes	60%, Required*
2024	Retroactive	Yes	NA	NA	60%, Optional
2025	Look Back	No	Yes	Yes	100%**, Required*
2025	Retroactive	Yes	NA	NA	100%**, Optional

* Required to follow the original tax return’s elections regarding bonus.
** 100% should the rental property be acquired and placed in service after Jan 19, 2025.

Generally, filing Form 3115 is preferred to amending tax returns for a handful of reasons-

• More economical in terms of professional fees.

• No housekeeping troubles with “sandwiched” tax returns where multiple years might need to be amended.

• Less hassles with state tax returns.

• Amending tax returns is usually limited to the prior 3 or 4 years, or what is sometimes referred to as “open” tax returns. Theoretically, there is no limit to how far back you can go using a look-back cost segregation study with Form 3115.

However, as mentioned previously, there might be reasons specific to that tax year which necessitates the amendment.

The big takeaway with all this is- The bonus depreciation percentage is based on when the rental property was acquired and placed into service, and not when the cost segregation study is performed or when Form 3115 is filed. In other words, if your rental property was placed in service (ready and available for occupancy, and held out for rental use through advertising and related efforts) in 2023, you are limited to 80% bonus depreciation. If you fired up the rental in 2024, then 60%. But, if you had it placed in service in 2022, then you get to use that year’s bonus depreciation which was 100%.

The good news is that 100% bonus depreciation is back for the 2025 through 2030 tax years thanks to the One Big Beautiful Bill Act (OBBBA) that was recently signed into law in July 2025.

By Jason Watson, CPA
Posted Monday, September 29, 2025

As alluded to in other areas, a cost segregation study and the subsequent accelerated depreciation including Section 179 expensing is like JG Wentworth where you want your money, and you want it now. Bad reference?

Let’s say it this way- if you take two rental properties, both short-term rentals, and one had a cost segregation study done and the other did not, at the end of 39 years, your tax deduction for depreciation is identical. The same. There aren’t any special tax deductions provided by a cost seg. So, why do real estate investors and rental properties think this is crack?

It’s all about getting your cash sooner, and re-deploying it to earn more money (or paring down debt).

Let’s assume a $700,000 rental property purchase with a building value of $500,000, which in fancy accounting speak is your depreciable basis. Who wants more assumptions? Sure, let’s assume $100,000 in accelerated depreciation and a marginal tax rate of 24%, and your cost of equity is 8% (or your average rate of return for redeploying your cash).

Next, let’s ponder this table-

Cost Segregation Case Study

		With Cost Segregation				No Cost Segregation
Year		Depreciation	Tax Savings	Invested		Depreciation	Tax Savings	Invested
1		100,000	24,000	25,920		12,821	3,077	3,323
2		10,256	2,462	30,652		12,821	3,077	6,912
3		10,256	2,462	35,763		12,821	3,077	10,788
4		10,256	2,462	41,282		12,821	3,077	14,974
5		10,256	2,462	47,243		12,821	3,077	19,495
6		10,256	2,462	53,681		12,821	3,077	24,378
7		10,256	2,462	60,634		12,821	3,077	29,651
8		10,256	2,462	68,143		12,821	3,077	35,346
9		10,256	2,462	76,253		12,821	3,077	41,497
10		10,256	2,462	85,012		12,821	3,077	48,140

Mid-point rates of return aside including first-year depreciation conventions, and other nerdy math, this table suggests that spending $1,000ish on a cost segregation study will yield an extra $37,000 in your pocket after 10 years ($85,012 less $48,140).

If your cost of equity or rate of return on re-deployed cash increased to 10%, then this difference is $45,000. What about 37% marginal tax bracket and 10% cost of equity? Our numbers increase to $152,000 and $83,00, or about a $70,000 delta.

Some might say, wow, ok, that really isn’t a big needle push for me. Others might say, yeah, where do I sign? Everyone is different, with different objectives.

Keep in mind that-

• This assumes you can actually deduct your accelerated depreciation either with rental profits from other rental properties, short-term rental loophole or real estate professional status.
• Your desired rate of return might not be fully adjusted for the risk of a big fat tax deduction associated with accelerated depreciation. In other words, your desired rate of return investing into Amazon or Google might be different than a rental property purely based on risk. An 8% return on Amazon might be risk-adjusted to 12% on a rental property when faced with a choice. As a quickie sidebar, cost of equity usually reflects your desired rate of return when considering two investments, and is common in finance and investment real estate.
• When you grab that big sexy depreciation deduction in year 1, your subsequent years are more painful. Look at the table again- depreciation goes down on a year-by-year basis since you grabbed a bunch in year 1. WCG CPAs & Advisors recently had a client with a $14M building and had a massive $8M depreciation deduction (very special case)- he loved life in year 1, but had sizeable tax bills in subsequent years.
• To expand on the concept just mentioned, if your marginal tax rate increases in later years, you might want some depreciation in your back pocket. An ace up your sleeve so-to-speak. The table above assumes a stable tax footprint which might not be your situation. Then again, most people worry about next time, next time.

Planning To Sell Soon?

Old school mentality suggested that if you plan to sell your rental property within 5 years, then do not perform a cost segregation study. We say “old school” because in many ways this assumed your cost seg cost was $5,000 or more. Today, with do-it-yourself cost segregation, the math is better.

Basically, it comes down to this- cost segregation’s only job is to convert a portion of IRC Section 1250 property into IRC Section 1245 property, and then allow you to accelerate depreciation with bonus depreciation or use Section 179 expensing. As such, how much is the extra cash today that you will have to pay back upon sale in a year or two, worth to you?

In most situations, WCG CPAs & Advisors encourages you to complete the cost segregation study and take your tax deduction (assuming your facts allow you to) today. Quick math- spend $1,000 on a cost seg. Save $37,000 on $100,000 in accelerated depreciation. Earn 8% on $37,000 each year, or over $6,000. Spend $1,000 to get $6,000? Might make sense, Yes?

One more thing to keep in mind- let’s say your income is unusually high this year. You received a big bonus or a large RSU payout, and things will come back down to earth the following year. The year of high income is a good time to pair with a cost segregation study and accelerated depreciation. Your tax deduction is at a 37% marginal tax bracket (play along please), and upon sale your marginal tax bracket is now 24%. This is a 13% tax arbitrage based on timing and good tax planning. 13% applied to a $100,000 depreciation tax deduction is real money (plus the interest on that savings for several months).

By Jason Watson, CPA
Posted Monday, July 7, 2025

Here are some FAQs you might find helpful for cost segregation studies-

What is a cost segregation study?
It’s a tax strategy that separates building components into shorter-life categories (5, 7, or 15 years) to accelerate depreciation.

Is cost segregation considered an abusive tax shelter?
No. It’s based on court decisions and IRS guidance. Properly done, it’s a fully legal tax strategy not deemed abusive or evasive.

Why would I want to accelerate depreciation?
Faster depreciation reduces your taxable income in the early years of owning a rental property, improving cash flow. Improved or accelerated cash flow can then be redeployed.

What’s the difference between Section 1245 and 1250 property?
Section 1245 is personal property (faster depreciation, subject to recapture), while Section 1250 is real property / structural (slower depreciation).

Can I do a cost seg study myself through an online service?
Yes for most single family homes and similar rental properties. Don’t believe the audit risk hype- a tax return is not prepared with some “DIY Cost Seg” box checked. We recommend CostSegEZ.com.

What is bonus depreciation?
An accelerated method allowing large amounts of first-year depreciation deduction of qualifying property. For the 2025 tax year, bonus depreciation is back to 100% for property placed in service after January 19, 2025, thanks to the One Big Beautiful Bill (OBBB). However, 2023 remains at 80% and 2024 remains at 60%.

Can short-term rentals benefit from cost seg?
Yes, STRs with 7-day average guest stay and material participation can use accelerated depreciation (bonus) and even Section 179 expensing effectively well.

Does cost segregation work for residential rentals?
Absolutely. Even single-family homes can benefit, especially when paired with REPS or STR strategies.

What’s Form 3115 used for?
It’s required to retroactively apply cost segregation (change in accounting method) and calculate Section 481(a) adjustment which is fancy accounting speak to bring depreciation current as if it always was done correctly and deduct accordingly.

Can I apply cost segregation study to Rental properties purchased in prior years?
Yes, very common. By using a look-back study and Form 3115, you can catch up missed depreciation without amending tax returns. There is tax arbitrage with this approach given each tax year might have different circumstances with income, rental property use and material participation.

When does cost segregation not make sense?
When passive activity loss limits prevent you from using accelerated depreciation or when you plan to sell soon. Accelerated depreciation and state matters can mess things up too since nearly 20 states do not allow for bonus depreciation.

Can I use cost seg in a year with a net tax loss across all rental properties?
You can, but benefits may be limited if losses are suspended due to passive rules. Better in REPS or STR loophole environments.

What’s a partial asset disposition (PAD)?
PAD allows you to deduct as a loss the undepreciated value of components you remove during renovations or major system repairs (think HVAC and commercial buildings).

Will I pay more in taxes later because of depreciation recapture?
Possibly. When you sell a rental property, Section 1245 recapture is taxed at ordinary income tax rates whereas Section 1245 recapture is limited to 25%.

How much can I save with cost segregation?
Savings vary by property, but 20% to 40% of the purchase price is often reclassified, leading to significant accelerated depreciation. It depends on building value as a portion of the price, and typical home stats such as size, age, bedrooms, bathrooms, etc.

Do I need to amend old returns to do a retroactive cost seg?
No. Use Form 3115 to make a change in accounting method instead. Amending might be necessary to use Section 179 expensing in favor of bonus depreciation.

How often can I do cost segregation?
Once per property, typically. You can reclassify again after major renovations or improvements.

Do states follow federal cost seg rules?
Not always. Some states disallow bonus depreciation or limit accelerated methods including Section 179 expensing.

Does cost seg apply to improvements or only new purchases?
It applies to both. Renovations can be analyzed separately for faster depreciation.

What are the risks of DIY cost segregation?
Improper asset classification and weak documentation (shocker).

What is the main benefit of a cost segregation study?
The primary benefit is improved cash flow now. Although total depreciation over 39 years is the same with or without cost segregation, front-loading the deductions allows you to get more money upfront—which you can then reinvest or use to pay down debt.

Does cost segregation create extra tax deductions?
No. Over the long run, the total depreciation is the same. Cost segregation just accelerates the timing of deductions, allowing you to take more in the early years and less in the later ones.

How does accelerated depreciation impact future tax years?
Since you take a larger deduction in year 1, you’ll have less depreciation available in future years. This can lead to higher taxable income and larger tax bills in those later years.

Can I always take full advantage of accelerated depreciation?
Not necessarily. You must have enough rental income or passive gains to absorb the deduction, or you must qualify under exceptions like the short-term rental loophole or real estate professional status.

By Jason Watson, CPA
Posted Sunday, May 25, 2025

It is not surprising that many rental property owners who use a do-it-yourself cost segregation tool such as CostSegEZ.com want to push down land values which inherently increases the building value. This in turn pushes up the value of the property that can be accelerated.

As mentioned previously, the easiest way to determine this is using the county assessor’s ratio. Let’s say you purchase a rental property for $500,000, and according to the assessor’s data the parcel is assessed at $45,000 land and $180,000 building for a total of $225,000. In this example, land is 20% and using this ratio, you could assume that land is $100,000 on your $500,000 purchase leaving $400,000 as building.

The Internal Revenue Manual, Part 4. Examining Process, Chapter 48. Engineering Program, Section 6. Real Property Valuation Guidelines, and specifically under 4.48.6.3 Documenting subparagraph 2, states “assessment and tax data” should be considered when determining value. Ok, that is quite the mouthful.

How about a tax court case? In Nielson v. Commissioner, Tax Court Summary Opinion 2017-31, the court concluded that a county assessor’s allocation to land and improvement values were more reliable than the taxpayers’ proposed values. The tax court also noted they could not find any authority that suggests a taxpayer is qualified to allocate the value of the property between land and improvements. Boom!

If you disagree with the county assessor ratio method, then spend the money on an appraisal- the opinion of a disinterested third-party will usually be viewed favorably if challenged.

Another consideration is the average cost per square foot building costs. If you purchase a lovely short-term rental property in Malibu, and want to claim that $1.8 million of the $2.5 million purchase price is the building allocation for an 1,800 square foot property, you might be pushing it. This would be $1,000 per square foot construction costs. Location, location, location, right? Sure, building costs can easily exceed $500 a foot and even $1,000 a foot depending on finishes and construction complexity, but you need to be careful.

Yet another consideration is the discussion and application of replacement cost found in the Cost Segregation Audit Techniques Guide. Here is a blurb-

When construction cost information for the acquired property is not available, it must be estimated using the construction cost data, methods, and techniques normally employed for a property appraisal. These estimated property costs (replacement cost new (RCN)), which include indirect costs, are then adjusted for the asset’s age and condition at the acquisition date, including physical depreciation, functional obsolescence, and economic obsolescence. These adjustments are generally expected to be different among the various items of acquired property (e.g., a building and its structural components, land improvements, and personal property), given that each of these items of property have varying expected useful lives, levels of use, and may have been constructed and/or installed on different dates. The total replacement cost new less depreciation (RCNLD) of the acquired items of property, along with the fair market value (FMV) of the land, should reasonably approximate the total purchase price of the acquired property.

Ok, neat. Later on, in the ATG, the IRS issues this guidance for examination-

Ensure that Replacement Cost Values are Properly Adjusted
for the actual condition and remaining economic useful life of the assets.

The value of used components must be reduced from the replacement cost new value in proportion to the observed economic obsolescence or physical depreciation as compared to similar new assets. This principle is discussed in regard to the “Helipot Building” in Lesser v. Commissioner, 42 T.C. 688 (1964), aff’d, 352 F.2d 789 (9th Cir. 1965), acq., 1966-2 C.B. 5, cert. Denied, 384 U.S. 927 (1966).

And they pile on with this-

Real Estate Allocations
The fair market value of land should be based on the highest and best use of the land as though vacant, even if the land has improvements. The land value may equal the value of the total real estate even if the real estate has substantial improvements when such improvements do not contribute value to the property. Whereas land has value, improvements contribute value. The value of the total real estate, less the value of the land, results in the contributory value of the improvements. Accordingly, it is inappropriate to estimate the value of the land by subtracting the estimated value of the improvements from the lump real estate price. Basis assigned to land in this residual fashion may result in understating the appropriate basis in the land and overstating the appropriate basis in the depreciable improvements. Examiners should also be wary if a cost segregation study relies solely on local assessed values rather than appropriately determining fair market values.

Yuck. The bottom line to all this- use the county assessor ratio method supported by the Nielson tax court case, and apply some common sense with building and replacement costs as compared to the age of the purchased building.

By Jason Watson, CPA
Posted Sunday, May 25, 2025

A cost segregation study, or “cost seg” as your bartender advises, can be extremely beneficial. But there are problems to navigate through, and like Robert Plant used to sing, (not) all that glitters is gold and sometimes words have two meanings.

Another consideration- should you benefit from a cost segregation study and the related big tax deduction, then perhaps pairing this with a Roth conversion on your traditional IRA makes sense as well. Tax planning is a must!

At the risk of repeating ourselves, whether this accelerated rental property depreciation yields a tax deduction / tax benefit and therefore increased cash flow (an improved IRR) is contingent on three general things-

• Short-term rental loophole (7 days average guest stay + material participation), or

• Real Estate Professional designation (REP status), or

• Net rental income (profit) that can be reduced

Go forth and cost seg!

By Jason Watson, CPA
Posted Sunday, May 25, 2025

Bonus depreciation election is assumed. Rental property owners who fail to elect out of bonus depreciation and do not claim bonus depreciation are using an improper accounting method. Sounds naughty, right? You would need to file Form 3115 Application for Change in Accounting Method to cure.

There are some tax planning opportunities since opting out of bonus depreciation can be asset class specific. For example, you could opt out of 5-year property but not 7-year or 15-year property. This allows you to thread the needle on balancing today’s tax deduction with tomorrow’s future tax deductions relative to your taxable income.

By Jason Watson, CPA
Posted Sunday, May 25, 2025

The fee for a cost segregation study varies between $750 to a bajillion dollars. There are two types of cost seg reports- one is routinely called “do it yourself” and the other is a fully engineered report. The fully-engineered report is very similar to a property appraisal- there is a site visit, a bunch of measurements and pictures are taken, and a qualified person dissects the property to create the 5-, 7- and 15-year piles. Costs range from $2,500 to $6,000 for most rental properties under $2 million(ish).

There is a depreciable property value of about $1,500,000 where things change. Below that value, the statistical reliability and therefore predictability is very good, and most cost segregation reports can rely on basic property vitals such as address, age, price, square footage, etc. plus a quickie survey of the stuff inside. What stuff? According to CostsegEZ.com, here is a quick list-

• Removable floor coverings (i.e., carpet, vinyl, LVP, floating wood)

• Kitchen cabinets and countertops

• Kitchen appliances (including mechanical, electrical, plumbing connections)

• Laundry appliances (including mechanical, electrical, plumbing connections)

• Window treatments

• Ceiling fans

• Electrical wiring and outlets for telephones (really?!), televisions, internet

• Closet shelving

• Decorative trim and wall coverings

• Decorative light fixtures (including electrical connections)

• Hot tubs and pool equipment (see our hot tub conundrum)

• Security systems

• Furniture and decor

• Window air conditioning units

WCG CPAs & Advisors has a similar list that we use for renovations where we do a “poor man’s” version of cost segregation when a rental property owner details out a renovation or rental rehab. We discuss this later. Riveting!

How does a do it yourself cost segregation report work again? Said another way, the cost segregation report is relying on a slew of prior reports to homogenize the data and draw correlations to the basic property vitals and a survey of certain components. Plus, this technique has been successfully defended in multiple courts. Is there a risk? Are there standards?

According to IRS Publication 5653 Cost Segregation Audit Techniques Guide (ATG)–

Neither the Internal Revenue Service (Service) nor any group or association of practitioners has established any requirements or standards for the preparation of cost segregation studies. The courts have addressed component depreciation but have not specifically addressed the methodologies of cost segregation studies.

The Service has addressed this issue but only briefly, i.e., Revenue Ruling 73-410, 1973-2 C.B. 53, Private Letter Ruling (PLR) 7941002 (June 25, 1979), Chief Counsel Advice Memorandum 199921045 (April 1, 1999). These documents all emphasize that the determination of § 1245 property is factually intensive and must be supported by corroborating evidence. In addition, an underlying assumption is that the study is performed by “qualified individuals” and “professional firms” that are competent in design, construction, auditing, and estimating procedures relating to building construction (See PLR 7941002).

Despite the lack of specific requirements for preparing cost segregation studies, taxpayers still must substantiate their depreciation deductions and classifications of property. Substantiation using actual costs is more accurate that using estimates. However, in situations where estimation is the only option, the methodology and the source of any cost data should be clearly documented. In addition, estimated costs should be reconciled back to actual costs or purchase price.

The big takeaway from the blurb is the phrase “factually intensive.” It appears 7 times in the ATG. When shopping for a DIY cost seg provider, ensure you are comfortable with their reporting and see if their results feel “factually intensive.” However, do not be discouraged from using a do-it-yourself cost segregation provider- many are extensions of fully-engineered cost seg experts, and will prepare a full report should you be audited.

By Jason Watson, CPA
Posted Sunday, May 25, 2025

How does all this black magic work? With a cost segregation report, or some say a cost segregation study, all the sticks, bricks and stuff inside are figuratively torn down and put into different piles. Some piles are eligible for instant depreciation (unlike the hominy grits in My Cousin Vinny), one pile might be a 5-year pile, another be a 15-year pile, and the remaining pile might revert to the 27.5- or 39.0-year typical residential or non-residential commercial use depreciation.

Sidebar: A short-term rental property that has an average guest stay of 7 days or fewer where you materially participate in the activity is considered a commercial activity, and as such will be 39.0 years. We discuss the short-term rental (STR) loophole in great detail.

Technically, and with full-on geek-speak, cost segregation separates property elements that are “dedicated, decorative or removable” from those that are “necessary and ordinary for operation and maintenance of the building.” These piles are called asset classes, and they are maintained separately within your property’s depreciation schedule.

From there, and with the help of bonus depreciation and in some cases Section 179 expensing, you compress the multiple years into one. Yay! Whether this accelerated rental property depreciation or expensing yields a tax deduction / tax benefit and therefore increased cash flow (an improved IRR) is contingent on three general things-

• Short-term rental (7 days average guest stay + material participation), or

• Real Estate Professional designation, or

• Net rental income (profit) from the rental property, other rental properties, or other real estate investments that can be reduced by the loss.

Or some combination of the above. We’ll dig in deep on these goodies.

Please don’t groan as we go into the weeds with more nerdy accounting terms like Section 1245 and Section 1250 Property. This one is important, and we’ll try to keep it relevant. A building that is or has been depreciable is considered Section 1250 property. When a cost segregation study is performed, certain asset classes are deemed personal property and when depreciable, they become Section 1245 property.

Why do you care? Not to get too far off track, but one of the big benefits of identifying property as Section 1245 property is that it becomes eligible for Section 179 expensing (there are additional exceptions as Qualified Improvement Property or QIP for short). There is a downside too- depreciation recapture, which we have not discussed yet, is limited to 25% on Section 1250 property, but Section 1245 property is recaptured at your ordinary income tax rate. As such, this becomes a big tax planning consideration. Also, Section 1245 property does not always escape depreciation recapture in a Section 1031 Like-Kind Exchange either. We expand on this and the wonderful 15% exception.

Quick recap-

• 5- or 7-year property is Section 1245 property.

• 15-year property can be either Section 1245 or Section 1250 property. However, it is usually Section 1250 if attached to the land. Can you dig up a shrub and relocate it? Maybe. However, if you accelerate depreciation on 15-year property, such as land improvements, then it becomes Section 1245 property (which alters depreciation recapture slightly).

• 27.5- or 39.0-year property, such as the building and its structural components, is Section 1250 property.

Sidebar: Asset Class 00.3, as defined by the IRS, refers to Land Improvements and mentions that they can be either Section 1245 or Section 1250 property. This is because assets that are integral to the manufacturing / production process are defined as Section 1245 property in IRC Section 1245(a)(3)(B). Therefore, a plant could have inherently permanent improvements to the land that would be considered Section 1245 property because they support the manufacturing / production process. A massive diversion in a book about rental properties, but you’re better for it.

How does the IRS distinguish between Section 1245 and Section 1250 property? According to IRS Publication 5653 Cost Segregation Audit Technique Guide (ATG)–

From a regulatory standpoint, the primary test for determining whether an asset is § 1245 property eligible for ITC [investment tax credit] is to ascertain that it is not a building or other inherently permanent structure, including items which are structural components of such buildings or structures. In other words, if an asset is not a building or a structural component of a building, then it can be deemed to be § 1245 property. The determination of structural component hinges on what constitutes an inherently permanent structure, how permanently the asset is attached to such a structure and whether it relates to the operation or maintenance of the structure. See Treas. Reg. §§ 1.48-1(c)-(e).

ITC references investment tax credit. How does that matter? IRC Section 1245(a)(3) and Treasury Regulations Section 1.1245-3(b)(1) read that the distinction between tangible personal property (Section 1245) and structural components (Section 1250) should be based on the criteria once used to determine whether property qualified for the now repealed investment tax credit (ITC) under IRC Section 38.

Huh? The IRS is using old tax code to define current tax code. You still awake? In 1975, the IRS refined its definition and stated in Revenue Ruling 75-178,

Rather, the problem of classification of property as ‘personal’ or ‘inherently permanent’ should be made on the basis of the manner of attachment to the land or the structure and how permanently the property is designed to remain in place.

As such, the inherently permanent test, is illustrated in the landmark Whiteco Industries, Inc. v. Commissioner, 65 Tax Court 664 (1975) court case. No, we don’t bore you with all the factors, but it is an interesting read if you cannot get enough.

You see the IRS Publication 5653 Cost Segregation Audit Technique Guide (ATG) here-

wcginc.com/6777

By Jason Watson, CPA
Posted Sunday, May 25, 2025

Chapter 6 explains how real estate investors can significantly accelerate depreciation by reclassifying components of a building into different asset classes allowing for time compression. Instead of depreciating an entire property over 27.5 or 39 years, a cost segregation study “tears down” the property into 5-, 7-, or 15-year property.

This chapter begins with the fundamentals, tracing how cost segregation evolved from court rulings and IRS publications, and then walks through practical application from engineered reports to DIY tools. It breaks down Section 1245 versus 1250 property classification, bonus depreciation, and how to handle partial asset disposition. The mechanics of Form 3115 and IRC Section 481(a) are covered in depth for retroactive and look-back cost segregation application.

Importantly, we also explain when cost seg is a tax-smart move (e.g., REPS, STRs, or profitable years) and when it might backfire (e.g., passive loss limitations, recapture risk, audit exposure).

By Jason Watson, CPA
Posted Sunday, May 25, 2025

When you buy real estate for business or rental use, you can depreciate the entire purchase price, minus the land value, over 27.5 or 39.0 years depending on the designated use (residential versus nonresidential / commercial / short-term). This can feel like forever. Not just forever, but forever and ever.

For example, if you purchase a $400,000 single-family rental property and $100,000 is attributed to the land, you can depreciate about $10,909 annually. This is 3.64% of the $300,000 value attributed to the building.

At a mid-range marginal tax rate of 24%, this puts $2,618 into your pocket. Not shabby. But what if you could depreciate in big chunks? What about $60,000 in one year (which is a good starting point using our example above)? Now you get to put $14,400 extra in your pocket during the first year. Accelerated cash flow is always nice. Time-value of money. All that stuff. Yay!

How did we get here? Several items in a building do not last 27.5 or 39.0 years. Recall that one of the fundamentals to depreciation is to expense the asset over its useful life. However, carpeting, lighting, heating or cooling systems, cabinets, landscaping, and land improvements might not last as long as the building itself.

Thankfully the tax court recognized this issue in Hospital Corporation of America v. Commissioner, 109 Tax Court 21 (1997). In response, the IRS issued an Action on Decision (AOD) 1999-008 on August 30, 1999. In part, it reads-

On their tax returns for 1985 through 1988, the taxpayers classified as tangible personal property certain items in hospital facilities constructed in those years and took depreciation deductions for them using a 5-year recovery period … The Commissioner determined that the items were structural components of the hospital facilities and not tangible personal property and, therefore, should be depreciated over the same recovery period as the facilities to which they related.

In the Tax Court, the taxpayers argued that the items constituted section 1245 property, and, therefore, were appropriately depreciated using a 5-year recovery period … Further, the Commissioner argued that section 168(f)(1) effectively operates to change the definition of tangible personal property after 1981, thereby precluding such property item from being classified as section 1245 property, if it is attached to a building and has utility beyond its relation to a particular piece of property. It was the Commissioner’s position that the items were structural components and thus section 1250 property and, therefore, should be depreciated over the same recovery period as the building to which they relate.

The Tax Court found that most of the assets at issue were section 1245 property. The Court rejected the Commissioner’s primary argument stating that the test developed with respect to ITC and Treas. Reg. § 1.48-1(e) were inappropriate after the enactment of ACRS in 1981. The court concluded, after reviewing the statutory and regulatory language and case law, that, while Congress did prohibit the use of component depreciation, there was no intent to redefine section 1250 property under ACRS to include property that had been section 1245 property for purposes of the investment tax credit.

As a result, the IRS relented, and stated in their AOD,

We acquiesce in this decision to the extent that the Tax Court held that the term “tangible personal property,” as defined under a pre-1981 ITC analysis, has continued viability under ACRS and MACRS. The issue as to whether the various disputed items are structural components or tangible personal property is a factual question. We do not agree with the court’s determination with respect to the various disputed properties. We cannot state, however, that the court was clearly erroneous.

We’ll review what 1245, 1250, investment tax credit, and the terms above mean.

Cost Segregation Study Mechanics

How does all this black magic work? With a cost segregation report, or some say a cost segregation study, all the sticks, bricks and stuff inside are figuratively torn down and put into different piles. Some piles are eligible for instant depreciation (unlike the hominy grits in My Cousin Vinny), one pile might be a 5-year pile, another be a 15-year pile, and the remaining pile might revert to the 27.5- or 39.0-year typical residential or non-residential commercial use depreciation.

Sidebar: A short-term rental property that has an average guest stay of 7 days or fewer where you materially participate in the activity is considered a commercial activity, and as such will be 39.0 years. We discuss the short-term rental (STR) loophole in great detail.

Technically, and with full-on geek-speak, cost segregation separates property elements that are “dedicated, decorative or removable” from those that are “necessary and ordinary for operation and maintenance of the building.” These piles are called asset classes, and they are maintained separately within your property’s depreciation schedule.

From there, and with the help of bonus depreciation and in some cases Section 179 expensing, you compress the multiple years into one. Yay! Whether this accelerated rental property depreciation or expensing yields a tax deduction / tax benefit and therefore increased cash flow (an improved IRR) is contingent on three general things-

• Short-term rental (7 days average guest stay + material participation), or

• Real Estate Professional designation, or

• Net rental income (profit) from the rental property, other rental properties, or other real estate investments that can be reduced by the loss.

Or some combination of the above. We’ll dig in deep on these goodies.

Please don’t groan as we go into the weeds with more nerdy accounting terms like Section 1245 and Section 1250 Property. This one is important, and we’ll try to keep it relevant. A building that is or has been depreciable is considered Section 1250 property. When a cost segregation study is performed, certain asset classes are deemed personal property and when depreciable, they become Section 1245 property.

Why do you care? Not to get too far of track, but one of the big benefits of identifying property as Section 1245 property is that it becomes eligible for Section 179 expensing (there are additional exceptions as Qualified Improvement Property or QIP for short). There is a downside too- depreciation recapture, which we have not discussed yet, is limited to 25% on Section 1250 property, but Section 1245 property is recaptured at your ordinary income tax rate. As such, this becomes a big tax planning consideration. Also, Section 1245 property does not always escape depreciation recapture in a Section 1031 Like-Kind Exchange either. We expand on this and the wonderful 15% exception.

Quick recap-

• 5- or 7-year property is Section 1245 property.

• 15-year property can be either Section 1245 or Section 1250 property. However, it is usually Section 1250 if attached to the land. Can you dig up a shrub and relocate it? Maybe. However, if you accelerate depreciation on 15-year property, such as land improvements, then it becomes Section 1245 property (which alters depreciation recapture slightly).

• 27.5- or 39.0-year property, such as the building and its structural components, is Section 1250 property.

Sidebar: Asset Class 00.3, as defined by the IRS, refers to Land Improvements and mentions that they can be either Section 1245 or Section 1250 property. This is because assets that are integral to the manufacturing / production process are defined as Section 1245 property in IRC Section 1245(a)(3)(B). Therefore, a plant could have inherently permanent improvements to the land that would be considered Section 1245 property because they support the manufacturing / production process. A massive diversion in a book about rental properties, but you’re better for it.

How does the IRS distinguish between Section 1245 and Section 1250 property? According to IRS Publication 5653 Cost Segregation Audit Technique Guide (ATG)–

From a regulatory standpoint, the primary test for determining whether an asset is § 1245 property eligible for ITC [investment tax credit] is to ascertain that it is not a building or other inherently permanent structure, including items which are structural components of such buildings or structures. In other words, if an asset is not a building or a structural component of a building, then it can be deemed to be § 1245 property. The determination of structural component hinges on what constitutes an inherently permanent structure, how permanently the asset is attached to such a structure and whether it relates to the operation or maintenance of the structure. See Treas. Reg. §§ 1.48-1(c)-(e).

ITC references investment tax credit. How does that matter? IRC Section 1245(a)(3) and Treasury Regulations Section 1.1245-3(b)(1) read that the distinction between tangible personal property (Section 1245) and structural components (Section 1250) should be based on the criteria once used to determine whether property qualified for the now repealed investment tax credit (ITC) under IRC Section 38.

Huh? The IRS is using old tax code to define current tax code. You still awake? In 1975, the IRS refined its definition and stated in Revenue Ruling 75-178,

Rather, the problem of classification of property as ‘personal’ or ‘inherently permanent’ should be made on the basis of the manner of attachment to the land or the structure and how permanently the property is designed to remain in place.

As such, the inherently permanent test, is illustrated in the landmark Whiteco Industries, Inc. v. Commissioner, 65 Tax Court 664 (1975) court case. No, we don’t bore you with all the factors, but it is an interesting read if you cannot get enough.

You see the IRS Publication 5653 Cost Segregation Audit Technique Guide (ATG) here-

https://wcginc.com/wp-content/documents/tax/IRS_Cost_Segregation_Audit_Technique_Guide_Publication_5653.pdf

Do It Yourself Cost Segregation Study

The fee for a cost segregation study varies between $750 to a bajillion dollars. There are two types of cost seg reports- one is routinely called “do it yourself” and the other is a fully engineered report. The fully-engineered report is very similar to a property appraisal- there is a site visit, a bunch of measurements and pictures are taken, and a qualified person dissects the property to create the 5-, 7- and 15-year piles. Costs range from $2,500 to $6,000 for most rental properties under $2 million(ish).

There is a depreciable property value of about $1,500,000 where things change. Below that value, the statistical reliability and therefore predictability is very good, and most cost segregation reports can rely on basic property vitals such as address, age, price, square footage, etc. plus a quickie survey of the stuff inside. What stuff? According to CostsegEZ.com, here is a quick list-

• Removable floor coverings (i.e., carpet, vinyl, LVP, floating wood)

• Kitchen cabinets and countertops

• Kitchen appliances (including mechanical, electrical, plumbing connections)

• Laundry appliances (including mechanical, electrical, plumbing connections)

• Window treatments

• Ceiling fans

• Electrical wiring and outlets for telephones (really?!), televisions, internet

• Closet shelving

• Decorative trim and wall coverings

• Decorative light fixtures (including electrical connections)

• Hot tubs and pool equipment (see our hot tub conundrum)

• Security systems

• Furniture and decor

• Window air conditioning units

WCG CPAs & Advisors has a similar list that we use for renovations where we do a “poor man’s” version of cost segregation when a rental property owner details out a renovation or rental rehab. We discuss this later. Riveting!

How does a do it yourself cost segregation report work again? Said another way, the cost segregation report is relying on a slew of prior reports to homogenize the data and draw correlations to the basic property vitals and a survey of certain components. Plus, this technique has been successfully defended in multiple courts. Is there a risk? Are there standards?

According to IRS Publication 5653 Cost Segregation Audit Techniques Guide (ATG)–

Neither the Internal Revenue Service (Service) nor any group or association of practitioners has established any requirements or standards for the preparation of cost segregation studies. The courts have addressed component depreciation but have not specifically addressed the methodologies of cost segregation studies.

The Service has addressed this issue but only briefly, i.e., Revenue Ruling 73-410, 1973-2 C.B. 53, Private Letter Ruling (PLR) 7941002 (June 25, 1979), Chief Counsel Advice Memorandum 199921045 (April 1, 1999). These documents all emphasize that the determination of § 1245 property is factually intensive and must be supported by corroborating evidence. In addition, an underlying assumption is that the study is performed by “qualified individuals” and “professional firms” that are competent in design, construction, auditing, and estimating procedures relating to building construction (See PLR 7941002).

Despite the lack of specific requirements for preparing cost segregation studies, taxpayers still must substantiate their depreciation deductions and classifications of property. Substantiation using actual costs is more accurate that using estimates. However, in situations where estimation is the only option, the methodology and the source of any cost data should be clearly documented. In addition, estimated costs should be reconciled back to actual costs or purchase price.

The big takeaway from the blurb is the phrase “factually intensive.” It appears 7 times in the ATG. When shopping for a DIY cost seg provider, ensure you are comfortable with their reporting and see if their results feel “factually intensive.” However, do not be discouraged from using a do-it-yourself cost segregation provider- many are extensions of fully-engineered cost seg experts, and will prepare a full report should you be audited.

Opted Out of Bonus Depreciation

Bonus depreciation election is assumed. Rental property owners who fail to elect out of bonus depreciation and do not claim bonus depreciation are using an improper accounting method. Sounds naughty, right? You would need to file Form 3115 Application for Change in Accounting Method to cure.

There are some tax planning opportunities since opting out of bonus depreciation can be asset class specific. For example, you could opt out of 5-year property but not 7-year or 15-year property. This allows you to thread the needle on balancing today’s tax deduction with tomorrow’s future tax deductions relative to your taxable income.

Cost Segregation Pitfalls

There are two big pitfalls and a fewof gotchas.

Pitfall #1. If you are considering a cost segregation study on a rental property, and that activity is considered a passive activity, your tax deduction is limited to $25,000 (passive loss limit). If you earn over $150,000 as a household, your tax deduction might be limited to $0. Yes, you are reading that zero correctly. We discuss passive activity loss limitations later on page xx.

There are two ways to get around this. First, if you qualify as a real estate professional, then your passive activity loss limits go away. To be a real estate professional as defined by the IRS and not what you hear at the bar, an individual must spend more than half of the personal services performed in all businesses and activities during the year in real estate activities. As a reminder, this includes the following-

real property development, redevelopment, construction, reconstruction, acquisition, conversion, rental, operation, management, leasing, or brokerage trade or business.

Read this again! If you have another full-time job in which you work 40 hours a week, you will need to work more than 40 hours per week in your real estate business and related activities. Having a W-2 is a red flag, as they say, straight out of the Passive Activities Loss Audit Techniques Guide (ATG) from the IRS.

Next, your hours worked in real estate activities must be more than 750 hours. Any work performed as an investor cannot be counted. There are a bunch of other devils in the details. Yes, most real estate agents qualify, not because they are real estate agents but rather time spent on real estate activities.

Finally, you must materially participate as defined by the IRS in each rental activity. We dive deep into real estate professional or REP status or just “REPS” as the cool kids say in a later section.

The other way to get around the passive loss limits is to have the activity not be considered passive. Makes sense right? Let’s just pencil-whip this activity and add the word “non-“ in front of it all. Done!

To be a non-passive activity, the average stay in the rental must be 7 days or less. Your typical VRBO Airbnb situation. However, you must also materially participate (there’s that darn word again) in the activity. Alternatively, for average stays of 30 days or less, you provide hotel-like services like changing linens during the stay or providing tours (think hunting lodge).

These two situations are considered non-passive activities and losses are not limited. As a small sidebar, or perhaps a minibar, the first example is reported on Schedule E, and the second is on Schedule C possibly subject to self-employment taxes.

Pitfall #2. If you can’t escape the passive activity loss limits, then you must have net rental income from the rental property or from other properties or real estate investments to absorb the accelerated depreciation expense and grab that accelerated cash flow. Self-rentals, where you own the building and lease it back to your business, do not usually absorb passive losses from other rentals. We talk about self-rentals later.

Gotcha #1. Recall that depreciation is a tax deferral. When you sell the property, you have depreciation recapture which simply means you must pay back the deferred taxes. There is some tax arbitrage here, however, since recapture is limited to a 25% tax rate on Section 1250 property (remember our mini chat about this) where you might have deducted depreciation at a 37% marginal tax rate. You can also escape this gotcha with a Section 1031 Like-Kind Exchange.

Sidebar: Recall that Section 1245 property, which might be “created” with a cost segregation report, is recaptured at ordinary income tax rates. We stated that earlier. However, the intersection of Section 1031 and Section 1245 can be problematic since you cannot like-kind exchange Section 1245 property. As such, you can perform a pretty Section 1031 Like-Kind Exchange, and still have a tax bill because of the sale of Section 1245 property in connection with the overall rental property sale.

Gotcha #2. The cost of the report or cost segregation study must be significantly lower than the improved time-value of the accelerated cash flow. In other words, the juice must be worth the squeeze, including the audit risk.

Another way to look at Gotcha #2- accelerated depreciation is not extra depreciation. Two rentals, one with a cost segregation study and one without, will be fully depreciated at 27.5 years. As such, it is purely a time-value of money compared to fee consideration. Then again, if you take the tax savings (deferral in reality) and blast off on a fun vacation, that has value too, right?

Gotcha #3. The last gotcha is one that is often overlooked. A cost segregation study and the subsequent big depreciation deduction is a one and done event. The following tax year, your depreciation comes down to earth and is actually less than it would normally be. Keep mind that cost segregation accelerates depreciation; it does not create new or phantom depreciation. Take a $780,000 building that would normally depreciate $20,000 per year. If you accelerate $150,000 in depreciation the first year, years 2 through 39 will be $16,600ish (versus $20,000).

Summary

A cost segregation study, or “cost seg” as your bartender advises, can be extremely beneficial. But there are problems to navigate through, and like Robert Plant used to sing, (not) all that glitters is gold and sometimes words have two meanings.

Another consideration- should you benefit from a cost segregation study and the related big tax deduction, then perhaps pairing this with a Roth conversion on your traditional IRA makes sense as well. Tax planning is a must!

At the risk of repeating ourselves, whether this accelerated rental property depreciation yields a tax deduction / tax benefit and therefore increased cash flow (an improved IRR) is contingent on three general things-

• Short-term rental loophole (7 days average guest stay + material participation), or

• Real Estate Professional designation (REP status), or

• Net rental income (profit) that can be reduced

Go forth and cost seg!