Your client replaces a $400,000 roof. You capitalize it on a 39-year life and move on. From that moment the fixed asset schedule depreciates two roofs: the new one on the building and the old one in the landfill.
The partial asset disposition election under Treas. Reg. §1.168(i)-8 fixes that, and it is probably the most missed election in real estate tax. It is annual, the only visible transaction is an invoice for something new, and nothing on the return complains when you skip it.
Key takeaways
- Treas. Reg. §1.168(i)-8 permits an election to recognize a loss on the remaining adjusted basis of a replaced building component — a roof, HVAC unit, windows, an elevator.
- The election is annual, made on a timely filed return including extensions for the year of the disposition, and generally irrevocable. Miss the year and the opportunity is generally gone.
- Three benefits, not one: a current ordinary loss, an end to depreciating an asset you no longer own, and a smaller §1250 recapture exposure on eventual sale.
- Basis of the disposed component may be established three ways: the Producer Price Index discounting method, pro-rata allocation, or a component cost study.
- If the work is a deductible repair under the RABI test, there is no disposition to elect on. Test that first.
The Problem: Two Roofs, One Building
A building is a single asset for depreciation purposes, and its components are folded into that basis. Absent an election, nothing removes a replaced component's remaining basis; it keeps depreciating alongside its replacement for the rest of the recovery period.
On a 2012 building with a 2026 roof replacement, that is roughly 25 more years of depreciation on a roof that is gone, plus 39 years on the roof that replaced it. The client is not harmed in total dollars, but the timing is badly wrong. The election converts an eventual recovery into a current deduction, and on a large component that is a substantial swing.
What the Election Actually Gives You
An immediate ordinary loss equal to the remaining adjusted basis of the disposed component.
An end to phantom depreciation. The old component leaves the schedule. Small in any one year, meaningful across a portfolio with regular replacement cycles.
Reduced §1250 recapture exposure, the benefit most practitioners underweight. Unrecaptured §1250 gain is taxed at a maximum 25% rate to the extent of straight-line depreciation taken on the structure. Removing the old component's basis takes that slice out of the future computation. Our overview of depreciation recapture covers the interaction.
Before You Elect: Is There Even a Disposition?
Run the tangible property regulations first. Under Treas. Reg. §1.263(a)-3, an expenditure is capitalized only if it is a Betterment, an Adaptation to a new or different use, or a Restoration. If the work is a deductible repair, the client already deducted 100% of it and there is nothing to elect on.
The building systems rule usually decides it. The improvement analysis applies separately to the structure and to each enumerated building system, which is why a job that looks small against the whole property is often large against the HVAC system alone. The repair versus improvement analysis is the necessary companion here. RABI first; if capitalized, ask what the new component replaced.
The Mechanics: Annual, Timely Filed, Generally Irrevocable
The election is made by reporting the gain or loss on the timely filed original return, including extensions, for the year the disposition occurs. There is no separate form; the reporting is the election. It applies to that disposition, in that year, and is generally irrevocable.
Say the consequence plainly to clients and staff: there is no catch-up mechanism for a partial disposition election you did not make. A look-back study recovers missed depreciation for any prior year through Form 3115 and a §481(a) adjustment, because that is a method change. Failing to make an available election is not. The two get confused, and the confusion is expensive.
So catch it in real time. Every capitalized building improvement should trigger the question "what did this replace?" before the asset is added. The IRS Audit Techniques Guide lists identification of §1245 property leading to a partial disposition among the elements of a quality study, and a properly built study gives you the component detail to answer quickly.
Three Accepted Ways to Value the Disposed Component
Producer Price Index discounting. Discount the replacement component's actual cost back to the placed-in-service year using an appropriate PPI series. Best where the original cost records do not break out the component, which describes most acquired buildings. Cite the series and both index values.
Pro-rata allocation. Allocate the building's original basis to the disposed component proportionally, typically by square footage or a documented cost ratio. Appropriate where the component is a clean fraction of a homogeneous whole, such as one floor of windows.
Component cost study. Price the component as originally installed, from actual cost records or an engineering reconstruction. The most defensible method, and the natural output when a cost segregation study already exists.
Worked Example: A 2012 Building and a 2026 Roof
Example: nonresidential building placed in service June 2012 with $4,200,000 of depreciable basis. Entire roof membrane replaced in August 2026 at a cost of $400,000. The original cost records do not separate the roof, so the PPI discounting method is used. Assume the applicable PPI series stood at 100.0 in the placed-in-service month and 152.0 at replacement, a ratio of 1.52.
| Step | Computation | Amount |
|---|---|---|
| Replacement roof cost, 2026 | Contractor invoice | $400,000 |
| PPI ratio, 2012 to 2026 | 152.0 ÷ 100.0 (assumed) | 1.52 |
| Deemed 2012 cost of disposed roof | $400,000 ÷ 1.52 | $263,158 |
| Depreciation allowed, Jun 2012 – Aug 2026 | 39-year SL, mid-month | ($95,591) |
| Adjusted basis of disposed component | $167,567 | |
| Ordinary loss recognized in 2026 | $167,567 | |
| Illustrative tax effect at 35% | ~$58,650 |
Three things follow. The client deducts $167,567 in 2026 instead of recovering it over 25 years. The building's basis drops by that amount, reducing future unrecaptured §1250 gain. And the new $400,000 roof begins its own 39-year life, though a nonresidential roof is §179-eligible under §179(f), which for a client with sufficient business taxable income can accelerate most of the replacement cost too. The number is only as good as the index series behind it, so cite it.
Where Partial Disposition Claims Fall Apart
The computation has to be documented. A PPI computation with no cited series and no index values is not workpaper-grade. Show the series name, both index values, the periods, and the arithmetic; an examiner should be able to reproduce it without calling you.
Watch the deduction-versus-disposition contradiction. You cannot deduct the replacement as a repair and also claim a disposition loss on what it replaced. Pick a position and hold it across the schedule.
The PPI method discounts cost, not specification. If the new roof is a materially better assembly than the old, the discounted figure overstates the original, and the difference should be addressed rather than ignored.
Late identification is the biggest killer. Most missed elections are missed because the improvement was booked in March and nobody asked what came out. Fix the workflow, not the return. Our guide for CPA firms covers building the review step into the annual fixed asset process.
Frequently Asked Questions
Can I make a late partial asset disposition election?
Generally no. The election must be made on a timely filed original return, including extensions, for the year the disposition occurred. That is why the analysis has to happen alongside the improvement rather than in a later cleanup.
What if a cost segregation study already exists for the building?
That is the best case. The study's asset detail gives you a component cost study basis directly, which is more defensible than PPI discounting and faster to prepare. It is one of the underappreciated ongoing benefits of a properly detailed study.
Does this work on a residential rental property?
Yes. The election is not limited by property type, and the mechanics are identical on a 27.5-year building. Apartment portfolios with rolling roof, HVAC, and window replacement programs are among the strongest candidates.
How does this interact with a tenant buildout?
Directly. A buildout that demolishes existing partitions, ceilings, and lighting has disposed of components carrying remaining basis. The renovation and tenant improvement analysis runs in both directions: classify what went in, dispose of what came out.
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This article is provided by Precision Cost Segregation for general educational purposes and does not constitute tax, legal, or accounting advice. Tax outcomes depend on your specific facts, your tax rate, your passive activity position, and your entity structure. Figures shown are illustrative. Consult your CPA or tax advisor before acting, and engage a qualified professional to perform any cost segregation study. Information is current as of publication.
This article is general information, not tax or legal advice. Depreciation outcomes depend on your facts, elections, and current law — consult your CPA before acting. © 2026 Precision Cost Segregation.