Real estate tax

Cost segregation

Depreciation front-loads the deductions that make real estate cash-flow positive and tax-negative. Cost segregation pulls them forward by years, and 2025 made the payoff permanent.

Depreciation is the reason a rental property can send you cash every month and still show a loss on your tax return. Cost segregation is how you take that loss and pull years of it into the present.

How we got here

The tax code makes you write a building off slowly: 27.5 years for residential rental property, 39 years for commercial. But a building is not one asset. Its carpet, cabinets, dedicated wiring, and parking lot wear out far faster than its foundation. For a stretch, the code refused to see that. The 1981 and 1986 depreciation systems banned component depreciation, forcing every part of a building onto the same long clock.

In 1997 the Tax Court reopened the door. In Hospital Corporation of America v. Commissioner, it held that many building components are Section 1245 personal property, not Section 1250 real property, and can be depreciated over their own shorter lives. The IRS accepted the result in 1999. Every cost-segregation study performed today rests on that distinction.

The payoff came later. The 2017 tax law brought back 100% bonus depreciation, then began phasing it down, reaching 40% for 2025 and heading toward zero. In July 2025 the One Big Beautiful Bill Act reversed that: 100% bonus depreciation is permanent again for property placed in service after January 19, 2025, and the Section 179 expensing cap rose to $2.5 million. The short-life property a study uncovers is now fully deductible in year one, with no expiration.

What cost segregation actually does

A worked example, illustrative only; a real study and your CPA set the actual numbers.

Buy a rental for $1,000,000. After carving out roughly $200,000 for non-depreciable land, you have $800,000 of building to depreciate. Straight-line, year one gives you about $29,000. Now run a study that reclassifies a quarter of the building, $200,000, into 5, 7, and 15-year property. With 100% bonus depreciation, that entire $200,000 is deductible in year one, on top of straight-line on the rest. First-year depreciation jumps from about $29,000 to roughly $222,000.

A building is not one asset, and cost segregation is the argument that its carpet should not depreciate on the same clock as its foundation.

With 100% bonus depreciation permanent again, every dollar a study moves into short-life property is a dollar you deduct in year one.

The cluster

This pillar covers when a study is worth its cost, bonus depreciation versus Section 179, residential versus commercial recovery periods, depreciation recapture, the repairs-versus-improvements line and the safe harbors that police it, partial asset dispositions, roof and HVAC replacements, qualified improvement property, the tangible property regulations, and the mistakes that turn a study into an audit.

The seam most advisors miss

A cost-segregation study is only as good as your ability to use the loss it creates, and that is not a depreciation question. It is a passive-activity question.

For most investors, rental losses are passive. They cannot offset wages or business income; they sit suspended until you have passive income or you sell. Run an aggressive study in a year you cannot use the loss and you have accelerated a deduction into a year it does nothing, while shortening your basis for a recapture bill later. The deduction is real; the timing can waste it. The fix lives in the advanced strategies pillar: real estate professional status, or the short-term-rental exception, can turn those passive losses active and let them reach your other income.

A cost-segregation study is worthless in a year you cannot use the loss, and whether you can is a passive-activity question, not a depreciation one.

Then there is the exit. Accelerated depreciation is a loan from your future self. When you sell, Section 1245 recapture is taxed as ordinary income and unrecaptured Section 1250 gain at up to 25%. A 1031 exchange postpones that reckoning; a straight sale triggers it. So the decision to segregate is really three at once: how fast to deduct, how you will use the loss, and how you plan to exit.

Accelerated depreciation is borrowed from your future self, and recapture is the repayment that only a 1031 exchange delays.

The bottom line

Cost segregation front-loads depreciation by reclassifying building components into short-life property.
With 100% bonus depreciation permanent, the year-one payoff is larger and no longer expiring.
The deduction only helps if you can use the loss, which depends on your passive-activity status.
Every accelerated dollar is subject to recapture on sale unless a 1031 exchange defers it.

Keep reading: entity and LLC tax strategies, 1031 exchanges and exit planning, and advanced real estate tax strategies. Back to the real estate tax resource center.

Last verified July 2026.

Inside this hub

What is cost segregation

A building is not one asset. Cost segregation splits it into parts and depreciates the fast-wearing ones on a faster clock, moving years of deductions into today.

Is a cost segregation study worth it

A study costs a few thousand dollars and can move six figures of deductions into year one. Whether that math works for you turns on three things, and one of them is not the building.

Bonus depreciation explained

Bonus depreciation lets you deduct the full cost of short-life property in year one. It was dying, phasing toward zero, until a 2025 law brought it back to 100% and made it permanent.

Section 179 vs bonus depreciation

Two ways to deduct an asset in year one, and they are not the same tool. One has a dollar cap and covers roofs and HVAC; the other has no ceiling and can create a loss. Real estate usually leans on one of them.

Residential vs commercial depreciation

Residential rental depreciates over 27.5 years, commercial over 39. The gap sounds small and quietly changes the size of every deduction you take, and the line between the two is not always where you think.

Depreciation recapture

Every dollar of depreciation you take is a dollar the IRS wants back when you sell. Recapture is the bill, and cost segregation, the thing that gave you the deduction, quietly makes the bill bigger and taxes it at a higher rate.

Repairs vs improvements

A repair is deductible this year. An improvement gets capitalized and deducted over decades. The line between them decides whether a $9,000 job saves you money now or in 2050, and the IRS has a specific test.

Safe harbor elections

Three IRS safe harbors let you expense things that might otherwise be capitalized, without fighting the repair-versus-improvement test. They are elective, easy to miss, and worth real money every year you use them.

Partial asset dispositions

When you tear out an old roof or HVAC system, you are still depreciating it on paper. A partial asset disposition lets you write off what is left of the old component in the year you replace it, instead of depreciating a thing that no longer exists.

Roof replacements

A new roof is the most common big-ticket item a landlord faces, and its tax treatment pulls together every rule in this pillar: repair or improvement, capitalize or expense, write off the old one, and which first-year deduction applies.

HVAC replacements

Replacing an HVAC system is a repair-or-improvement puzzle with a twist: the answer depends on how many units the building has. And on a commercial building, Section 179 can expense it even though bonus depreciation cannot.

Qualified improvement property

QIP is the one category of building improvement that gets a 15-year life and full bonus depreciation. It exists because Congress made a famous drafting mistake, fixed it years later, and then made it permanent.

Tangible property regulations

The tangible property regulations are the rulebook behind every repair-versus-improvement call, every safe harbor, and every partial disposition. They are the framework the rest of this pillar sits on.

Passive loss interaction

This is the rule that decides whether a cost-segregation study is worth anything. A study can hand you a six-figure deduction that you are not allowed to use, because rental losses are passive, and passive losses cannot touch your salary.

REPS and cost seg

This is the high earner's playbook, and the most audited pairing in real estate tax. Qualify as a real estate professional, run a cost-segregation study, and a six-figure depreciation loss lands directly against your W-2 income. The catch is the word qualify.

Common cost seg mistakes

Cost segregation is powerful and easy to get wrong. Every trap in this pillar in one place: the study that helps nobody, the deduction you cannot use, the audit you invited, and the bill that comes due at sale.

This is all free.

For anything involving the filing or management of your LLC, I'm your LLC guy.

If you're considering cost segregation, start with me. I've seen enough of these to know the right questions to ask, and with my gigantic Rolodex, I can put you in front of the person who actually handles it.

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