Cost Segregation Before a Sale: How It Works, Who It Fits, and the Catch

How cost segregation works

When you buy a commercial building, the default is to depreciate the whole building over 39 years (27.5 for residential rental). A cost segregation study, usually done by an engineer or a specialist firm, breaks the purchase price into its parts: carpet, cabinetry, dedicated electrical, specialty plumbing and similar items become 5- or 7-year property, and parking lots, landscaping, sidewalks and site utilities become 15-year land improvements.

Those shorter-life components qualify for bonus depreciation because their recovery period is 20 years or less (IRC 168(k)(2)(A)). The One Big Beautiful Bill Act made 100% bonus depreciation permanent for property acquired after January 19, 2025 (with no binding contract before that date). For buildings bought earlier, the old phase-down rates for the year the property was placed in service still apply.

If you have owned the building for years and never did a study, you do not amend old returns. You file Form 3115 for an automatic change in accounting method and take the missed depreciation as a single Section 481(a) adjustment in the year of change. That catch-up is why late studies get pitched to owners who are getting ready to sell.

The catch: recapture in the sale year

Depreciation on the 5- and 7-year components is Section 1245 property. When you sell, every dollar of depreciation taken on those components (up to the gain on them) comes back as ordinary income, taxed at rates up to 37%, not at the 20% capital gain rate (IRC 1245(a)). The 15-year land improvements are Section 1250 property, and depreciation above straight line on them, including bonus, is also recaptured as ordinary income under 1250(a).

Without a study, most depreciation on a building is straight line and becomes "unrecaptured Section 1250 gain," taxed at a maximum of 25%. So a study done shortly before a sale mostly converts tax you would have paid at 25% (or 20%) into tax at ordinary rates, one or two years later. The benefit is a timing and rate difference, not a permanent saving.

Recapture is also immune to installment reporting. Under IRC 453(i), all recapture income is recognized in the year of sale even if you receive only a small down payment. More cost segregation means more tax due in year one of a seller-financed deal.

Who it fits, and who it does not

• Fits: owners who will hold for several more years, so the deduction compounds before any recapture.
• Fits: real estate professionals or owners with passive income who can actually use a large deduction this year, at a high marginal rate.
• Fits: owners planning a 1031 exchange into property with enough Section 1245 property to absorb the recapture (IRC 1245(b)(4)).
• Fits: heirs, because a basis step-up at death wipes out the recapture exposure.
• Does not fit: a cash sale or installment sale within a year or two, where the deduction and the recapture land at similar rates.
• Does not fit: passive investors with no passive income, whose deduction is suspended and then released in the sale year, right next to the recapture.
• Does not fit: California filers looking for a state benefit. California does not follow federal bonus depreciation (R&TC 17250(a)(11)).

Worked example

Assumptions (engine, 2026 federal rules, married filing jointly, Texas, no state income tax): a rental building held since 2015 sells in 2026. Without a study, the sale produces $1,000,000 of capital gain plus $500,000 of unrecaptured Section 1250 gain, on top of $150,000 of other income. A study filed the year before the sale adds $400,000 of extra depreciation through a 481(a) catch-up, and that deduction offsets $400,000 of non-passive ordinary income in a $900,000 income year.

Net: about $140,643 of tax avoided one year, about $131,022 paid back the next. The roughly $9,600 difference plus one year of use of the money is the benefit, before the study fee. It exists here only because the deduction hit a higher bracket than the recapture. If the deduction had been suspended under the passive loss rules and released in the sale year, the two would largely cancel. Numbers are illustrative engine output, not a forecast.

IRS stance and audit risk

Cost segregation itself is legitimate and well settled. The Tax Court accepted component-based classification in Hospital Corporation of America v. Commissioner, 109 T.C. 21 (1997), and the IRS publishes a Cost Segregation Audit Techniques Guide (Publication 5653) that tells examiners what a quality study looks like: an engineering-based approach, documentation tied to construction records or site inspection, and a reconciliation to total cost.

Audit risk comes from weak studies: aggressive classification of structural items (walls, roofs, HVAC serving the building) as personal property, residual estimation without support, or ignoring land. The other common error is at sale: failing to report recapture, or allocating almost nothing of the price to the reclassified components when the contract or appraisal says otherwise. This is not a listed transaction or a transaction of interest.

Costs and fees

• Study fee, which varies with building size and complexity; desktop studies cost less than engineering site visits.
• Return preparation for Form 3115 and the 481(a) adjustment.
• Ongoing tracking of component basis so the right amount is recaptured when you sell or dispose of parts.
• The hidden cost: higher year-one tax at sale, which reduces the cash a seller-financed deal leaves you after closing.

How it compares with a Section 453 installment sale

The two tools work on different parts of the gain. An installment sale spreads capital gain and unrecaptured 1250 gain across the years you collect the note, which can keep more of it in lower brackets and under the NIIT threshold. It cannot spread recapture. Cost segregation adds recapture, so it shrinks the part of the gain an installment sale can spread and raises the tax owed out of the down payment.

If you already did a study, an installment sale still helps with the rest of the gain; size the down payment to cover the year-one recapture tax. If you have not, and a sale or seller-financed deal is a year or two away, a study is usually a small timing play at best. If a 1031 exchange is the plan, recapture can be deferred when the replacement property carries enough Section 1245 property, which makes a study more attractive.

How Hans helps

The $5,000 Big Sale Tax Analysis models the deduction years and the sale year together, at your actual brackets and state, and compares a cash sale, an installment sale, a 1031 and the other paths side by side. You see whether a study adds anything after recapture and fees before you pay for one. Start with the one-year vs spread estimate or see the analysis.

Frequently asked questions