Cost Segregation in 2026: 100% Bonus Depreciation Is Back (OBBBA Changes Explained)

The old playbook is dead. For years, investors watched bonus depreciation shrink from 100% down toward zero — until the One Big Beautiful Bill Act (OBBBA), signed on July 4, 2025, permanently restored 100% bonus depreciation. Cost segregation in 2026 is now more powerful than it has been in years.

What OBBBA Changed: The Short Version

Under the Tax Cuts and Jobs Act, bonus depreciation was scheduled to phase down: 40% in 2025, 20% in 2026, and 0% from 2027 on. OBBBA scrapped that schedule for qualifying property.

What this means: every dollar your cost segregation study reclassifies into 5-, 7-, or 15-year property can be deducted in year one — indefinitely. Per IRS guidance (Notice 2026-11), the key test is that the property was both acquired and placed in service after January 19, 2025.

Important: This post was updated in September 2026 to reflect OBBBA. Older articles (including earlier versions of this one) describing the 40%/20%/0% phase-down describe the pre-OBBBA law and no longer apply.

Why This Is a Bigger Deal Than It Sounds

Let's run the numbers on a typical deal:

Property: $1.5 million residential rental (excluding land) Cost segregation result: 25% reclassified to short-life property ($375,000) Tax bracket: 35% OBBBA puts $78,750 more in your pocket in year one on the same property. That's the time value of money working at full power: deductions today are worth far more than deductions spread over decades.

What Qualifies for 100% Bonus Depreciation

• New and used property both qualify. Acquiring an existing rental building counts, as long as you acquired it after January 19, 2025.
• The "placed in service" date is what matters. Your property must be acquired and placed in service after January 19, 2025.
• Improvements count too. Major renovations and improvements placed in service after the cutoff qualify on their own.
• State taxes are separate. Some states (Michigan is one well-known example) decouple from federal bonus depreciation and require an add-back on your state return. You still get the full federal benefit — check your state's rules with your CPA.

What's NOT Changing

1. The Cost Segregation Methodology

Cost segregation itself — the engineering-based reclassification of building components into shorter depreciation lives — is a methodology that has existed for decades. OBBBA only changed the bonus rate on top of it. The IRS Cost Segregation Audit Techniques Guide still governs how studies must be performed.

2. Look-Back Studies Still Work

Bought property in the last 15 years and never did a study? You can still do a look-back cost segregation study and catch up on missed depreciation via Form 3115 (the 481(a) adjustment) — no amended returns needed.

3. Section 179 Still Exists

Section 179 expensing remains available for qualifying assets, subject to its annual limits and phase-out thresholds. For most real estate investors, bonus depreciation is the bigger lever, but Section 179 is still in the toolbox.

What This Means for You in 2026

Property Buyers

There is no longer a bonus-rate cliff to race against. The strategy flips from "buy before the phase-down" to buying and placing in service under the permanent 100% regime. The only deadline that matters now is getting your study done so you can claim it on your return.

Current Owners (2023–2025 Purchases)

Property you already own doesn't retroactively qualify for the higher rate — but that doesn't mean you're leaving money on the table. A cost segregation study on a 2024 purchase still delivers accelerated depreciation over 5, 7, and 15 years instead of 27.5 or 39. And if you made capital improvements after January 19, 2025, those improvements may qualify for 100% bonus on their own.

Developers and New Construction

"Placed in service" is the operative date. Projects completing in 2026 fall squarely under the 100% regime — making this one of the best development environments in years from a tax standpoint.

Frequently Asked Questions

"Is 100% bonus depreciation really permanent this time?"

That's what the statute says: OBBBA restored 100% bonus depreciation on a permanent basis, not a temporary extension. Congress can always change the law again, but there is no phase-down scheduled.

"I read that bonus depreciation was dropping to 20% in 2026. Was that wrong?"

It was correct before OBBBA — that was the scheduled TCJA phase-down (40% in 2025, 20% in 2026, 0% in 2027+). OBBBA replaced it. Any article describing the phase-down is describing superseded law.

"Does this apply to property I bought in 2023?"

The 100% rate applies to property acquired and placed in service after January 19, 2025. A 2023 purchase doesn't get the 100% rate — but cost segregation still massively accelerates its depreciation schedule compared to straight-line. And renovations you do now can qualify.

"Can I combine a look-back study with 100% bonus on improvements?"

Yes — they're independent. A look-back study on your existing building catches up missed depreciation via Form 3115, while qualifying improvements placed in service after the cutoff get 100% bonus. Your CPA should coordinate the timing.

"My state doesn't follow federal bonus depreciation. Should I still do a study?"

In most cases, yes. State add-backs only affect your state return; the federal benefit — which is the much larger number — is unaffected. Run the numbers with your CPA, but don't let a state add-back kill a federal windfall.

The Bottom Line

2026 isn't the end of bonus depreciation — it's the reset to its most powerful form. Every year investors waited out the phase-down hoping for relief; that relief is now law, and it's permanent.

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