CalcStack — free, instant, no signup. The interactive calculator loads automatically.
100% bonus is back permanently — the study is what makes your building eligible for it.
Bonus depreciation only applies to property with a 20-year-or-shorter recovery period — and your building is 27.5 or 39 years. The cost segregation study is the mechanism that fixes that: it reclassifies 20–45% of the building's basis into 5-, 7-, and 15-year components (carpet, cabinetry, parking lots, landscaping), which 100% bonus depreciation — now permanent under OBBBA — expenses entirely in year one. A $1M rental jumps from a $27,273 first-year deduction to about $207,955. But the honest math includes the other side: reclassified components come back at ordinary rates (§1245) at sale, not the 25% §1250 cap, plus the study fee. This calculator nets all three.
Rental and commercial owners use it before commissioning the study: 100% bonus is permanent now, so the year-one deduction jumps 7–10×, and the honest net — minus the study fee and the ordinary-rate recapture at sale — decides whether the engineering report pays for itself.
Yes — OBBBA §70301 restored 100% bonus depreciation with no sunset for qualified property (20-year-or-less recovery period) acquired after January 19, 2025. The trigger is the acquisition date: property bought under a binding contract signed before January 20, 2025 stays on the old TCJA phase-down (40% for 2025, 20% for 2026). Anything you buy now gets the full first-year write-off, and the 5/7/15-year components a study identifies are exactly what qualifies.
Recapture at higher rates. Straight-line building depreciation comes back at the 25% §1250 cap — but reclassified personal property (5/7-year components) is §1245, recaptured at your full ordinary rate up to 37%. On a $187,500 reclassification in the 32% bracket, that's $13,125 of extra tax at sale versus no study — still far less than the $57,818 year-one saving, especially after a decade of compounding, and a 1031 exchange defers the recapture too. The real catch is for FLIPPERS: hold under ~2 years and the rate arbitrage evaporates.
Yes — a look-back study filed via Form 3115 generates a §481(a) catch-up adjustment: all the missed accelerated depreciation lands in the current year without amending old returns. One limit: bonus eligibility follows the original acquisition date, so a 2019 building gets accelerated MACRS on the reclassified components, not the 100% first-year write-off. Also verify your deductions aren't trapped by passive-loss rules — real estate professional status or the short-term-rental exception decides whether the loss offsets your other income.