Is 100% bonus depreciation back for 2025? Yes — permanently, under OBBBA.

Yes. The One Big Beautiful Bill Act (OBBBA, Pub. L. 119-21, signed July 4, 2025) permanently restored 100% bonus depreciation under IRC §168(k) for qualifying property both acquired and placed in service after January 19, 2025. Property acquired before that date generally stays on the prior TCJA phase-down even if placed in service later. The restoration is permanent under current law for property that meets the acquisition-date test — no further scheduled step-down.

Property with a MACRS recovery period of 20 years or less, including most cost-segregation reclassifications (5-year personal property, 15-year land improvements, qualified improvement property under IRC §168(e)(6)). The structural component of buildings (27.5-year residential, 39-year nonresidential) does NOT qualify for bonus — that's the whole reason cost segregation matters: it pulls eligible components out of the long-life structure bucket into bonus-eligible classes.

Qualified property generally receives 100% bonus depreciation if it was acquired and placed in service after January 19, 2025. Property acquired before January 20, 2025 generally remains subject to the prior TCJA phase-down based on its placed-in-service year — 80% for 2023, 60% for 2024, 40% for January 1–19, 2025, and 20% for 2026 — even if it's placed in service later than 2025. For cost segregation lookback studies (Form 3115 §481(a) catch-up), the depreciation calculation generally uses the bonus rules that applied when the property was originally placed in service, rather than the current 100% rate.

Yes — more so than during the phase-down years. With 100% bonus permanent, every dollar a study reclassifies from the 27.5- or 39-year structure into bonus-eligible 5-, 7-, or 15-year property becomes fully deductible in Year 1. On a $500K residential rental with a 22% reclassification, that's roughly $87,000 of Year-1 federal deduction at 100% bonus versus ~$15,000 of straight-line depreciation without a study. The whole point of cost segregation is maximizing the bonus-eligible bucket.

Internal Revenue Code §168(k) is the federal bonus depreciation provision. It allows taxpayers to deduct a specified percentage of the cost of qualifying property in the year placed in service, with the remaining basis depreciated normally over the asset's MACRS recovery period. TCJA temporarily set the rate at 100% (2017–2022), with phase-down to 0% by 2027; OBBBA permanently restored it to 100% effective for property both acquired and placed in service after January 19, 2025. Property acquired before that date remains on the TCJA phase-down schedule regardless of when it's placed in service.

Yes — TCJA expanded bonus eligibility to acquired-used property, and OBBBA preserved that expansion. As long as (1) the taxpayer didn't previously use the property, (2) the property wasn't acquired from a related party, and (3) it has the qualifying recovery period (≤20 years), used property qualifies for 100% bonus. This is critical for cost-seg buyers acquiring existing rental properties.

Form 3115 (Application for Change in Accounting Method) is the mechanism for claiming missed depreciation on property placed in service in a prior year. The §481(a) adjustment recovers all missed deductions in a single year. For property acquired before January 20, 2025, the catch-up applies the bonus rate in effect for the original placed-in-service year (40% for January 1–19, 2025, 60% for 2024, 80% for 2023, 100% for 2017–2022) — not today's 100% rate. No amended returns required; automatic-consent change under Rev. Proc. 2015-13.

Inconsistently. Many states decouple from federal bonus depreciation — Illinois, California, New York, New Jersey, and others require addback adjustments on their state returns. The federal Year-1 deduction is permanent and clean, but state treatment varies. Verify with your CPA before relying on bonus depreciation for state planning purposes.