100% Bonus Depreciation Is Back: What It Means for Cost Segregation in 2026

For the last few years, cost segregation came with an expiration-date anxiety. Bonus depreciation—the tax provision that makes cost segregation so powerful—was phasing down: 80% in 2023, 60% in 2024, 40% in 2025, 20% in 2026, and zero after that. Investors who knew about the cliff felt rushed. Investors who didn't missed out.

That entire calculus changed in July 2025. The One Big Beautiful Bill Act (OBBBA) permanently restored 100% bonus depreciation for qualifying property acquired after January 19, 2025. The IRS followed up with Notice 2026-11, giving taxpayers interim guidance on how the permanent rate works in practice.

If you own rental real estate, this is the single most important tax development in years. Here's what changed, how it affects cost segregation, and the moves to make now.

What Actually Changed

Before OBBBA, bonus depreciation was on a legislated death march set by the 2017 Tax Cuts and Jobs Act. The new law doesn't just pause the phase-down—it repeals it entirely:

The key phrase is permanent. No more timing acquisitions around a shrinking percentage. No more "do it this year or lose the deduction." Property owners can plan with confidence.

Why This Supercharges Cost Segregation

A cost segregation study reclassifies portions of your building—land improvements, fixtures, finishes—from 27.5- or 39-year property into 5-, 7-, or 15-year property. That reclassification only pays off in a big way if you can write those short-lived assets off quickly. That's exactly what 100% bonus depreciation does: it lets you deduct the entire reclassified amount in year one.

Let's put numbers on it. Say you buy a rental property for $800,000 (excluding land):

• A cost segregation study reclassifies roughly 30% — about $240,000 — into bonus-eligible property.
• Under the old 2026 rate (20%), your first-year bonus deduction on that amount would have been $48,000.
• Under the restored 100% rate, it's $240,000 — deducted in the first year you own the property.

That five-fold difference is the difference between cost segregation being "nice" and cost segregation being the highest-ROI tax move most investors can make. Compared to straight-line depreciation, the year-one deductions are roughly 7x larger.

Who Benefits Most

1. Recent buyers

If you acquired a property after January 19, 2025, you qualify for the permanent 100% rate. If you haven't done a cost segregation study yet, the timing has never been better—every year you wait is a year of accelerated deductions you push into the future.

2. Owners who bought during the phase-down

Bought between 2023 and 2025 and skipped cost segregation because bonus was "only" 40–80%? You can still do a look-back study and claim the missed deductions on your current return via an accounting method change (Form 3115)—no amended returns needed. A CPA can confirm your eligibility.

3. Investors planning acquisitions

The permanent rate removes the deadline pressure, but it doesn't remove the incentive. Every dollar of reclassified property now delivers a dollar of first-year deduction, for as long as you keep buying real estate.

What Didn't Change

• The building itself (27.5-year residential / 39-year commercial) still doesn't qualify for bonus depreciation. Only the reclassified short-life components do—which is exactly why the study matters.
• Land is never depreciable and never qualifies.
• Depreciation recapture still applies when you sell. (Bonus depreciation taken on 5/7/15-year property is generally recaptured as ordinary income, not at the favorable 25% unrecaptured §1250 rate—but the time value of money usually still wins by a wide margin.)
• Section 179 also got a boost under OBBBA: the deduction limit rose to $2.5 million with a $4 million phase-out threshold (2025 figures, inflation-adjusted for 2026). Section 179 and bonus depreciation can be combined strategically—your CPA should run both scenarios.

The Moves to Make Now

If you acquired property after January 19, 2025: get a cost segregation study before you file. The 100% rate applies to the tax year you place the property in service.

If you bought in the last few years and never did a study: ask your CPA about a look-back study with a Form 3115 catch-up deduction. The missed bonus from prior years can still be captured.

If you're buying now: factor accelerated depreciation into your underwriting. A property's tax benefits are part of its return—underwriting without them undersells the deal.

Talk to your CPA early: cost segregation changes your depreciation schedules, passive activity calculations, and exit planning. The earlier your CPA sees the report, the more you save.

The Bottom Line

The 100% bonus depreciation restoration turned cost segregation from a declining benefit into a permanent, first-year wealth-building tool. The investors who act on it—getting studies done, doing look-backs on past purchases, underwriting new deals with real tax numbers—will keep tens of thousands more per property.

The clock isn't ticking anymore. But the savings are still sitting on the table.

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