Many owners first hear about cost segregation after their short-term rental has been operating for a year or more. They may assume the opportunity disappeared when they filed the first return. In many cases, a study can still identify assets that were assigned to an incorrect recovery period, and the tax treatment can be corrected through an appropriate procedure. The opportunity is real, but the calculation must use the property’s original facts and the law applicable to its acquisition and placed-in-service dates.
A late study is not a way to apply the latest bonus depreciation rate retroactively to every old asset. It is a way to determine whether the existing depreciation schedule was correct and, if not, how to make a supported change. The value depends on the amount of basis still relevant, prior deductions, the owner’s ability to use a resulting adjustment, and the cost of the study and filing work.
Start with the current depreciation schedule
Before requesting a proposal, obtain every depreciation schedule filed since the STR began. Look for the original building basis, land allocation, furniture, appliances, improvements, dates placed in service, methods, and any bonus depreciation elections. Compare the schedule with the closing statement and capital improvements ledger.
The problem may be obvious: perhaps the entire purchase was placed into one building asset even though the sale included significant furnishings and site improvements. Or the original tax preparer may already have separately listed those assets, leaving less to gain from a study. Without reviewing the existing schedule, a provider’s estimate may double count assets already receiving shorter recovery periods.
Also identify whether the property has changed use. A former personal vacation home converted to rental use can have a different depreciation basis than a property purchased directly for rental. A property that later became a residence creates another set of questions. The study provider and tax preparer need the full chronology.
Gather the historical evidence
An older STR may be harder to study because closing photographs, inspection records, and contractor invoices have been lost. Begin with the purchase agreement, settlement statement, appraisal, tax assessment, inspection report, listings, floor plans, insurance records, and renovation invoices. Download historical booking data and find photographs showing the property close to the date it entered service.
For later improvements, collect contracts, payment records, permits, and completion dates. Do not blend a 2023 purchase with a 2025 renovation and assign all costs to one year. Each asset’s acquisition and placed-in-service facts may affect depreciation and bonus eligibility. If furniture was replaced, identify what was originally acquired and what was disposed of.
A good cost segregation provider can sometimes reconstruct costs from measurements, plans, photographs, and standard costing data when original construction records are absent. The IRS Cost Segregation Audit Techniques Guide discusses study methods and documentation. A reconstruction should explain its assumptions and reconcile to the owner’s actual basis.
Understand how the tax correction works
Tax returns cannot simply ignore depreciation already taken. The preparer must compare depreciation previously claimed with the amount that would have been claimed under the correct asset classifications. Depending on the prior filing history and type of error, a change in accounting method may be required or available. The process often involves Form 3115 and a Section 481(a) adjustment rather than amending each prior return, but it is not universal.
IRS Publication 946 explains that a change in depreciation method or recovery period can be an accounting-method change. The Form 3115 instructions describe the information needed for depreciation changes. A qualified preparer should determine whether the proposed correction is an automatic change, which designated change number applies, what filing procedures are required, and how to calculate the adjustment.
Do not accept a “catch-up deduction” number without a schedule showing prior allowed or allowable depreciation, the corrected depreciation through the beginning of the change year, and the resulting difference. The final amount may differ from the study provider’s marketing estimate. Elections, prior dispositions, and changes in use can alter the calculation.
Historical bonus rates still matter
The year you order a study does not usually determine the bonus depreciation percentage for assets that were acquired and placed in service years earlier. Applicable law, acquisition dates, placed-in-service dates, and elections must be reviewed for those historical years. Current IRS guidance describes 100% additional first-year depreciation for qualifying property acquired after January 19, 2025; that rule does not automatically redate an older purchase.
Similarly, a later replacement purchase can have its own eligibility. If an owner bought the home in 2022 and installed a new outdoor amenity in 2026, those are separate assets with separate facts. A useful study and asset ledger keep them distinct.
The building and land also remain subject to their own classifications. A cost segregation study can identify eligible components; it cannot transform all prior building cost into property that qualifies for bonus depreciation.
Will a catch-up adjustment reduce tax now?
The same loss limitations that affect a new study also affect a later adjustment. An STR owner needs to evaluate average customer-use periods and material participation under IRS Publication 925, as well as basis, at-risk, personal-use, and other rules. A large negative Section 481(a) adjustment might create a loss that is suspended rather than immediately offsetting wages.
Current facts can differ from facts in the acquisition year. If you operated the STR yourself when it opened but now use a full-service manager, your participation may be different. A tax projection should consider the change-year activity and the rules that govern the adjustment. It should also include the eventual sale, because accelerated deductions can increase later gain or recapture.
This is why “I missed $100,000 of deductions” is only the beginning of the analysis. What matters economically is the after-tax benefit and timing of those deductions compared with the cost and consequences of making the correction.
Example: a two-year-old furnished rental
Suppose an owner bought a furnished mountain home in 2024. The first two returns depreciated the entire depreciable purchase price as a single building asset, with no separate schedule for contents or land improvements. In 2026, the owner learns about cost segregation and obtains a property-specific report.
The report identifies assets that should have been classified separately at acquisition. The preparer then reconstructs the depreciation those assets should have received from their actual 2024 placed-in-service date and compares it with the depreciation already claimed. The applicable 2024 rules and prior elections must be used. If the correction qualifies as a method change, the preparer may calculate an adjustment for the change year and prepare Form 3115 under the applicable procedure.
The owner should also examine whether the 2026 deduction is currently usable. If it is suspended, the study can still be worthwhile, but the economic benefit may arrive later. If the owner expects to sell next year, recapture and remaining basis deserve special attention.
A decision process for an existing STR
- Collect returns and schedules. Find the original basis and all prior depreciation.
- Reconcile basis. Separate land, building, included contents, closing costs, and later improvements.
- Request a preliminary study estimate. Ask which property components were probably misclassified and how the estimate was derived.
- Have the preparer evaluate the correction route. Determine whether a method change or another filing action applies.
- Model the usable benefit. Include loss limits, study fees, filing costs, and likely sale consequences.
- Preserve the final report. Future depreciation and sale allocations will depend on it.
If records are incomplete, do not manufacture precision. Ask the provider what can be supported and what remains uncertain. A smaller well-documented allocation is preferable to a larger unsupported one.
Frequently asked questions
Is there a strict one-year deadline for a cost segregation study?
No general rule requires the report to be completed in the purchase year. The tax correction and available benefit depend on the facts and filing history. Earlier analysis is usually easier because records are fresher.
Do I need to amend every return since purchase?
Not necessarily. Some depreciation corrections are made through an accounting-method change and a cumulative adjustment. Other errors require different treatment. Your preparer should decide after reviewing the filed returns.
Can I apply 2026 bonus depreciation to a 2022 purchase?
Not merely because the study is done in 2026. The applicable rules depend on the asset’s own acquisition and placed-in-service facts and any elections. Later improvements may have different treatment from the original purchase.
Late can still be useful
An existing STR can still be a candidate for cost segregation, especially if its original depreciation schedule placed many assets into the building category. The answer requires a historical reconstruction and a current-year tax projection. AE Tax Advisors can help owners evaluate the study, coordinate any depreciation correction, and determine whether the resulting benefit is useful within their broader tax plan.
To review a property you already own, visit www.aetaxadvisors.com and request a tax assessment.
Related AE Tax Advisors guides: When Should You Order a Cost Segregation Study for an Airbnb Property?; What Records Should STR Owners Keep Before and After a Cost Segregation Study?.
Sources: IRS Cost Segregation Audit Techniques Guide; IRS Publication 946; IRS Form 3115 instructions; IRS Publication 925; IRS bonus depreciation guidance.