Best Time for Cost Segregation: 2025-2026 Window

Bonus depreciation just went back to 100% for residential rental property acquired and placed in service after January 19, 2025, and that single date change is why 2025-2026 is the best window in years to order a cost segregation study on an Airbnb, VRBO, or long-term rental.

Why this matters

Bonus depreciation was phasing down before the One Big Beautiful Bill Act (OBBBA) reset it. Properties placed in service in 2023 got 80%, 2024 got 60%, and the schedule was headed toward zero by 2027. OBBBA restores 100% bonus depreciation for qualifying property acquired and placed in service after January 19, 2025, which means a cost segregation study ordered now front-loads far more of the reclassified depreciation into year one than a study ordered under the old phase-down math.

That matters most for residential rental owners using the short-term rental loophole to offset W-2 income, because the entire strategy depends on how much depreciation can be claimed against active income in a single tax year. A study that identifies 25% of a property's value as 5, 7, or 15-year property is worth roughly twice as much in year-one cash tax savings at 100% bonus depreciation compared to the 60% rate that applied in 2024.

Who this is for

This window matters most to residential rental investors who bought or renovated a property after January 19, 2025, high W-2 earners using the STR loophole to offset active income, and owners sitting on properties from 2022-2024 who never claimed the depreciation they were entitled to. It also applies to owners planning a 1031 exchange or a cash-out refinance in 2026, since the timing of the reclassification interacts directly with the acquisition date rules.

What to look for when timing a cost segregation study in 2025-2026

Placed-in-service date relative to January 19, 2025

The single biggest lever in this window is whether your property was placed in service before or after January 19, 2025. Properties placed in service after that date qualify for 100% bonus depreciation under OBBBA, while earlier acquisitions may still be locked into the 60% rate that applied through 2024. Confirm your closing date and in-service date before assuming which rate applies.

Whether you can still meaningfully use the STR loophole this tax year

The short-term rental loophole requires material participation, and that clock resets each calendar year. If you're reading this in the back half of 2026, you still have time to hit the material participation thresholds, but the window narrows fast after Q3. A cost segregation study only creates a deduction; the loophole is what lets you apply it against W-2 or active income.

The size of the income you're trying to offset

Cost segregation produces the biggest cash benefit for high earners in the 37% bracket with substantial W-2 or 1099 income to shelter. A $46,250 tax savings on a $500,000 property assuming 25% reclassification and a 37% bracket is a meaningful number for a physician or executive, but far less impactful for someone in a 12% bracket with little other income to offset.

Acquisition versus renovation timing

Newly built or newly renovated properties placed in service in 2025 or 2026 get the cleanest 100% bonus depreciation treatment. Properties bought years ago but renovated recently need a study that separates the original basis from the renovation basis, since each may fall under different bonus depreciation rates depending on when each was placed in service.

How the study interacts with a 1031 exchange or refinance

If you're planning to combine cost segregation with a 1031 exchange, the timing of the study relative to the exchange closing date changes what basis gets reclassified. Order the study too early or too late relative to the exchange and you risk missing part of the reclassification opportunity on the replacement property.

Filing deadlines and extension timing

A cost segregation study needs to be in your CPA's hands before your return is filed, not after. If you're filing an extension into October 2026, you have more runway to order a study for the prior tax year than someone filing by the April deadline.

Scenarios where acting now pays off

The clean case: STR bought and placed in service after January 19, 2025

This is the simplest scenario in the entire 2025-2026 window. A short-term rental acquired and placed in service after January 19, 2025 qualifies for the full 100% bonus depreciation rate with no phase-down math to untangle. On a typical $500,000 property with 25% reclassified into short-life property, that's close to $125,000 in year-one depreciation. Verdict: Buy — order the study as soon as the property is placed in service and rented.

The biggest win: high W-2 earner closing before year-end

A physician or executive in the 37% bracket who closes on a cost segregation study for Airbnb and short-term rentals before December 31, 2026 can apply the full deduction against the current tax year's W-2 income, assuming material participation requirements are met. The math above puts that at roughly $46,250 in tax savings on a single property. Verdict: Buy, but confirm material participation days are logged before year-end.

The catch-up play: missed depreciation from 2022-2024

Owners who bought a rental in 2022, 2023, or 2024 and never ran a cost segregation study can still capture the missed depreciation through a Form 3115 change in accounting method, without amending prior returns. This doesn't get the 100% bonus rate retroactively for property placed in service before January 19, 2025, but it still catches up depreciation that should have been claimed years ago. Verdict: Consider — the benefit is real but smaller than a fresh 2025-2026 acquisition.

The stacked play: 1031 exchange closing in 2026

Investors rolling gains into a replacement property through a 1031 exchange in 2026 can order a cost segregation study on the new property shortly after closing, layering the 100% bonus depreciation rate on top of the deferred gain. This compounds two tax strategies into one filing year. Verdict: Buy, with the study ordered within weeks of closing, not months later.

The wildcard: renovated or remodeled properties

A property renovated in 2025 or 2026 creates two depreciation buckets: the original structure and the renovation cost. The renovation portion, if placed in service after January 19, 2025, can qualify for the 100% rate even if the original purchase happened years earlier. Verdict: Consider — the math depends heavily on how much of the total basis the renovation represents.

What to avoid

• Waiting until Q4 2026 to order a study for a property you plan to sell or refinance that year. A study takes 3-5 business days once site data is submitted, but CPA coordination and filing deadlines can eat that runway fast.
• Assuming a general CPA can do this without an engineering-based study. The IRS Cost Segregation Audit Technique Guide expects a detailed engineering analysis, not a rough percentage estimate, if the study is ever reviewed.
• Trying to apply this to a commercial property. Office buildings, self-storage, and multifamily commercial assets follow different rules and are outside residential cost segregation entirely; this window applies to Airbnb, VRBO, and residential long-term rentals.

Verdict comparison table

FAQ

One last thing

The 100% bonus depreciation rate under OBBBA has no scheduled expiration written into the current law the way the old Tax Cuts and Jobs Act phase-down did, but tax law changes with new legislation, and the last phase-down started in 2023 with almost no warning to investors. Ordering a study on a 2025 or 2026 acquisition now, rather than waiting for a slower filing season, locks in the reclassification analysis while the current rate structure holds.

Related guides

• STR loophole explained for W-2 earners
• How to catch up missed depreciation with Form 3115
• OBBBA bonus depreciation for rental property