If you own a residential rental and you're thinking about cost segregation for the 2026 filing year, bonus depreciation is probably the single biggest variable in the math. The difference between doing a study now versus waiting, or doing it on a 2025 acquisition versus a 2026 acquisition, can be tens of thousands of dollars of Year 1 tax impact. This guide walks through the current rules, the specific ways they apply to residential rentals, and what rental owners should actually do before year-end 2026.
The 2026 rules in one place
Bonus depreciation had been phasing down under the 2017 Tax Cuts and Jobs Act (TCJA) — 80% in 2023, 60% in 2024, scheduled to hit 0% by 2027. Then the One Big Beautiful Bill Act (OBBBA), signed July 4, 2025, changed everything by permanently restoring 100% bonus depreciation for property acquired after January 19, 2025.
So as of 2026, there are two regimes running in parallel:
| Acquisition date | Placed in service | Bonus rate |
|---|---|---|
| After Jan 19, 2025 | 2025 or 2026 | 100% |
| Binding contract before Jan 20, 2025 | 2025 | 40% |
| Binding contract before Jan 20, 2025 | 2026 | 20% |
The governing date is the acquisition date — specifically, the date on the binding purchase contract — not the placed-in-service date. That's a trap that catches people. If you signed a contract in December 2024 and didn't close until February 2025, you're on the TCJA phase-down schedule, not the OBBBA 100% regime. Your closing documents will tell you which one applies.
Why this matters so much for residential rentals
Residential rental buildings are 27.5-year property, which means the building shell itself doesn't qualify for bonus depreciation at any rate. Without a cost segregation study, you get exactly zero bonus depreciation on a rental purchase — the entire building basis sits in the 27.5-year bucket, and bonus depreciation only applies to property with a recovery period of 20 years or less.
Cost segregation is what unlocks it. The study reclassifies 10%–35% of the building basis into 5-, 7-, and 15-year property. That reclassified basis is where bonus depreciation does its work.
On a typical $400,000 single-family rental:
- Cost basis (building, not land): $320,000
- Typical reclassification into short-life buckets: $48,000 (~15% of building basis)
What happens to that $48,000 depends entirely on the bonus rate:
| Scenario | Year 1 deduction from short-life components |
|---|---|
| No cost segregation study (everything as 27.5-year) | $0 (no short-life components to deduct) |
| Cost segregation, no bonus (hypothetical) | ~$7,500 (normal MACRS on the short-life components) |
| Cost segregation + 20% bonus (old 2026 rate) | ~$15,600 |
| Cost segregation + 40% bonus (old 2025 rate) | ~$23,700 |
| Cost segregation + 100% bonus (OBBBA) | $48,000 |
The difference between "bonus at 20%" and "bonus at 100%" on the same property is roughly $32,000 of Year 1 deduction. At a 32% marginal tax rate, that's about $10,000 of additional first-year cash savings. Same property, same study — just different acquisition timing.
The short-term rental multiplier
Short-term rentals are in a particularly strong position in 2026. Here's why:
- Higher short-life reclassification. A furnished STR typically sees 20–35% of its building basis reclassified into short-life property, versus 10–15% on a long-term rental. More reclassification means more bonus depreciation impact.
- Non-passive treatment is available. If the average guest stay is 7 days or fewer and the owner materially participates, the losses from the rental are treated as non-passive, meaning they can offset W-2 or business income. Most rentals can't do this.
Combine these two factors with 100% bonus depreciation, and a $500,000 furnished short-term rental can easily generate $100,000+ of deductible loss in Year 1 that offsets the owner's active income. That's typically the single most impactful tax move available to a high-income earner who owns real estate. See our STR cost segregation guide for the full walkthrough.
What if you bought your rental before January 20, 2025?
You're not locked out — you're just in a different bucket. A few things to know:
- You're still on the TCJA phase-down schedule (80% in 2023, 60% in 2024, 40% in 2025, 20% in 2026). The OBBBA rate does not apply retroactively.
- The bonus depreciation rate that applies is the one in effect your placed-in-service year, not the year you do the study. If you bought the property in 2023 and do the study in 2026, you still get 80% bonus on the short-life components — because 80% is the rate that applied when the property was placed in service.
- Look-back studies let you recover the value. A look-back study provides the data your CPA needs to file IRS Form 3115 and claim all the missed depreciation, including the Year 1 bonus you should have taken. See our look-back study guide.
The punchline: even owners who bought during the bonus phase-down years can still capture meaningful value from a cost segregation study today. The numbers just aren't as big as they'd be on a post-January-19-2025 acquisition.
Planning decisions rental owners face in 2026
If you're buying a rental in 2026
Do the cost segregation study the same year you place the property in service. 100% bonus depreciation combined with a properly done study is the strongest possible first-year position. Don't wait until the following tax year unless there's a specific reason (like an income event) that would make a different year better for the deduction.
If you bought in 2025 after January 19
Same deal. 100% bonus applies. Do the study this year if you can, and make sure your CPA captures it on your 2025 return.
If you bought in 2025 under a pre-January 20, 2025 contract
You're on the 40% bonus rate, which is lower but still worth capturing. A cost segregation study still produces meaningful first-year savings — just not at OBBBA maximums.
If you bought in 2024 or earlier and never did a study
A look-back study is likely your best move. Your CPA uses the report to file Form 3115 and claim all the missed depreciation in a single catch-up adjustment on your current return. The bonus rate that applies is the one in effect when the property was originally placed in service — which, for 2022 acquisitions, was 100%.
If you're planning to sell soon
Run the numbers carefully. Depreciation recapture at sale reduces the net benefit, especially if you're selling within a few years. For a property held 5+ years, or held through a 1031 exchange, the math almost always favors doing the study.
State conformity (the footnote that matters)
Not every state conforms to federal bonus depreciation. Some states decouple from the federal rules and require you to recompute depreciation for state purposes on a straight-line basis. Your federal and state depreciation numbers may differ. Your tax preparer handles this at filing time, but it's worth knowing so the state bill doesn't come as a surprise.
Bottom line for 2026
100% bonus depreciation is back. It's permanent. It's the most favorable bonus regime residential rental owners have seen since 2022, and it transforms the math on cost segregation studies. If your property was acquired after January 19, 2025 — or if you're buying in 2026 — you're in the strongest possible window to do a study. If you bought earlier, you can still capture significant value, either on your current return or through a look-back study.
Use the free cost segregation calculator to see what the 2026 numbers look like on your specific property. It takes 30 seconds and gives you a real first-year estimate based on the bonus rate that applies to your acquisition.