Applying a cost segregation study to your federal tax return happens on two forms. Ongoing accelerated depreciation for the reclassified components is reported on Form 4562 each year. If the property was placed in service in a prior tax year, you also file Form 3115 to change your accounting method and claim a single-year Section 481(a) catch-up deduction for all the depreciation you would have taken had the assets been correctly classified from the start. A 2025 law change restoring 100 percent bonus depreciation makes those first-year numbers substantially larger for properties acquired after January 19, 2025.
Start With the Study’s Final Report
Nothing goes on the return until the engineering report is in hand. A defensible study breaks the property into components, assigns each to a specific MACRS recovery period (five-year, seven-year, fifteen-year, or the 27.5-year or 39-year shell), and reconciles every segregated cost back to the property’s original tax basis. The report should include photographs, a written explanation of each reclassification, and the tax authority supporting it.
Publication 946 lists appliances, carpets, and furniture used in residential rental real estate as five-year property. Land improvements such as shrubbery, fences, roads, sidewalks, and bridges fall into the fifteen-year class.1Internal Revenue Service. Publication 946 – How To Depreciate Property Whatever the study does not pull into a shorter category stays in the 27.5-year or 39-year bucket and continues to depreciate straight-line under the mid-month convention.
From that classified inventory you’ll pull three things onto your return: a line for each shorter-life asset class on Form 4562, a bonus depreciation figure if you’re entitled to one, and (for older properties) a Section 481(a) catch-up amount computed on Form 3115.
Reporting Ongoing Depreciation on Form 4562
Form 4562, Depreciation and Amortization, is where the yearly deductions are calculated and reported.2Internal Revenue Service. About Form 4562, Depreciation and Amortization After the study, you’ll run two depreciation schedules side by side: the accelerated schedule for the reclassified components and the standard schedule for the remaining shell.
The segregated five-year, seven-year, and fifteen-year property is reported in Part III, Section B, under the General Depreciation System. The remaining building components, still depreciating over 27.5 or 39 years, appear separately in Part III, Section C. Bonus depreciation on the qualifying assets is claimed in Part II.
Depreciation methods follow from the tax code once the recovery periods are set. Under IRC Section 168(b), five-year and seven-year property uses the 200 percent declining balance method, switching to straight-line in the year that produces a larger deduction, and fifteen-year property uses the 150 percent declining balance method.3Office of the Law Revision Counsel. 26 U.S. Code 168 – Accelerated Cost Recovery System
MACRS also uses placed-in-service conventions. The default for the personal property coming out of the study is the half-year convention, which treats every asset as placed in service at the midpoint of the year regardless of actual date. If more than 40 percent of the total depreciable basis placed in service during the year falls in the last three months, the mid-quarter convention applies instead and can reduce first-year deductions for assets placed in service early in the year.4eCFR. 26 CFR 1.168(d)-1 – Half-Year and Mid-Quarter Conventions The structural shell continues on the mid-month convention.
Where the Deduction Lands on Your Return
The total from Form 4562 flows to the return that matches how the property is held:
- Individual rental owners report it on Schedule E (Supplemental Income and Loss).
- Sole proprietors report it on Schedule C.
- Partnerships report on Form 1065, with each partner’s share passing through on Schedule K-1.
- Corporations report on Form 1120 or Form 1120-S.
Keep detailed depreciation schedules for every segregated asset showing cost basis, assigned MACRS life, method, and annual deduction. These schedules don’t get filed, but they’re your primary defense in an audit and are essential for computing gain or loss when any component is sold or replaced.
Form 3115 for a Property Placed in Service in a Prior Year
If you’re performing the study on a building that was placed in service in a prior tax year, the IRS treats the reclassification as a change in accounting method. You report it on Form 3115, Application for Change in Accounting Method.5Internal Revenue Service. Instructions for Form 3115 – Application for Change in Accounting Method You do not amend prior returns. The entire retroactive benefit comes through a single current-year catch-up deduction.
Automatic Consent and the DCN
The IRS grants automatic consent for this change, so there’s no user fee and no waiting for approval before claiming the deduction. On Form 3115, enter Designated Change Number 184, which covers changes in depreciation method, life, or convention for depreciable property.5Internal Revenue Service. Instructions for Form 3115 – Application for Change in Accounting Method Confirm you’re citing the current revenue procedure when you file, since the IRS updates the automatic-change list periodically.
One limit: automatic consent is generally unavailable if you’ve already changed the accounting method for the same asset within the preceding five tax years.
Computing the Section 481(a) Adjustment
The Section 481(a) adjustment is the full catch-up deduction. You compute it by subtracting the depreciation actually claimed under the old, longer lives from the depreciation that should have been claimed under the new, shorter lives, including any bonus depreciation that would have applied in the year each asset was placed in service. The result is a negative adjustment, taken entirely in the current year, and reported on Part IV, line 26 of Form 3115.5Internal Revenue Service. Instructions for Form 3115 – Application for Change in Accounting Method
On a $2 million commercial building where 30 percent of the cost is reclassified into shorter-life assets, this catch-up can run into six figures in the year the Form 3115 is filed.
Filing the Form and the Duplicate Copy
Two copies are required. The original is attached to your timely filed federal return (including extensions) for the year of the change. A signed duplicate copy goes separately to the IRS in Ogden, Utah, at Internal Revenue Service, Ogden, UT 84201, Attn: M/S 6111.6Internal Revenue Service. Where to File Form 3115 Failing to send the duplicate to the correct address can be treated as failing to file the form at all.
The Section 481(a) catch-up does not flow through Form 4562. Report it separately on the “Other Deductions” or “Other Expenses” line of the applicable return or schedule, clearly labeled as a Section 481(a) adjustment. The label matters: it lets the IRS tie the deduction back to the filed Form 3115 and heads off correspondence.
Bonus Depreciation by Acquisition Date
Bonus depreciation determines how much of the segregated basis you can write off in year one, and the rate depends on when the property was acquired.
For most owners filing 2026 returns, bonus depreciation is back to 100 percent. The One Big Beautiful Bill Act, signed in 2025, replaced the annual phasedown and permanently restored a full first-year deduction for qualified property acquired and placed in service after January 19, 2025.7Internal Revenue Service. Notice 2026-11, Interim Guidance on Additional First Year Depreciation Deduction All of the segregated five-year, seven-year, and fifteen-year components can be written off in the first year on a property purchased after that date.
Property acquired before January 20, 2025, remains on the original phasedown: 80 percent for 2023, 60 percent for 2024, 40 percent for 2025, and 20 percent for 2026.7Internal Revenue Service. Notice 2026-11, Interim Guidance on Additional First Year Depreciation Deduction When you prepare a Form 3115 catch-up for a building bought in, say, 2022, the bonus rate baked into each year of the Section 481(a) calculation is the rate that applied when the property was placed in service, not the rate in effect when the study is completed.
Can You Actually Use the Deduction? Passive Activity Rules
Accelerated depreciation only helps if the loss can offset income you actually have. Rental real estate is a passive activity by default, so the losses, including depreciation, generally offset only other passive income rather than W-2 wages or active business income.8Office of the Law Revision Counsel. 26 U.S. Code 469 – Passive Activity Losses and Credits Limited
There is a narrow exception. If you actively participate in managing a rental, you can deduct up to $25,000 of rental losses against non-passive income. That allowance phases out by $1 for every $2 of adjusted gross income above $100,000 and disappears entirely at $150,000 AGI.8Office of the Law Revision Counsel. 26 U.S. Code 469 – Passive Activity Losses and Credits Limited For married taxpayers filing separately who lived together at any point in the year, the allowance is zero.
The real unlock for higher earners is real estate professional status. Under IRC Section 469(c)(7), a taxpayer who meets both of the following tests can treat rental losses as non-passive and apply them against any type of income without limit:8Office of the Law Revision Counsel. 26 U.S. Code 469 – Passive Activity Losses and Credits Limited
- More than 50 percent of your personal services during the year are performed in real property trades or businesses in which you materially participate.
- You perform more than 750 hours of service during the year in those real property activities.
On a joint return, only one spouse needs to satisfy both requirements, but that spouse must meet them individually. The IRS scrutinizes these claims aggressively, and contemporaneous time logs are essential; after-the-fact estimates rarely survive in Tax Court. When the status holds, cost segregation becomes much more powerful because the full accelerated deduction, including a large Section 481(a) catch-up, can offset ordinary income.
State Returns Often Diverge
Federal cost segregation benefits don’t automatically carry through to the state return. Roughly half of states either fully decouple from federal bonus depreciation or impose their own modifications, requiring an addback of all or part of the federal bonus deduction when computing state taxable income. About 18 states and Washington, D.C. require a complete addback, and another 14 impose partial limitations such as per-asset caps or modified recovery periods.
The accelerated MACRS lives from the study still apply at the state level even where bonus depreciation is disallowed, so the study isn’t wasted. But the first-year state deduction will be smaller, and you’ll need to maintain two depreciation schedules going forward: one federal, one state.
Recapture When You Sell
Cost segregation shifts the tax bill rather than erasing it. On sale, depreciation claimed on the shorter-life assets is recaptured, and the rate depends on the class.
The five-year and seven-year assets are Section 1245 property. Gain attributable to depreciation on these assets is taxed as ordinary income at your full marginal rate, not at capital gains rates.9Office of the Law Revision Counsel. 26 U.S. Code 1245 – Gain From Dispositions of Certain Depreciable Property The recapture applies to the lesser of the gain recognized or the total depreciation previously claimed. On $200,000 of depreciation claimed against segregated personal property, a taxpayer in the 37 percent bracket faces $74,000 of recapture tax.
The structural shell and the fifteen-year land improvements are generally Section 1250 property. Gain attributable to straight-line depreciation on real property is taxed at a maximum rate of 25 percent as unrecaptured Section 1250 gain, and any gain above the depreciation amount is taxed at long-term capital gains rates. Investors who hold until death may avoid recapture entirely through stepped-up basis, and a 1031 exchange can defer it further. The larger the first-year benefit, the larger the eventual recapture, and the return positions you take today should account for that.