Cost Segregation for Rental Property in 2026

A cost segregation study is an engineering-based analysis that breaks a building's cost into its separate components and assigns each one its proper depreciation life. For a rental property, it moves a share of the purchase price off the 27.5 year or 39 year schedule and onto 5, 7, and 15 year lives. Since the One Big Beautiful Bill Act (OBBBA), signed July 4, 2025, those shorter-lived components can qualify for 100 percent first-year bonus depreciation.

What Is a Cost Segregation Study?

A cost segregation study identifies the parts of a building that are personal property or land improvements, and assigns them shorter recovery periods than the building itself. Without a study, most owners depreciate the entire building cost (minus land) over 27.5 years for residential rental property or 39 years for nonresidential real property. A study pulls out the components that the tax law treats differently.

The four buckets that matter most:

IRS Publication 527 lists appliances, carpets, and furniture used in residential rental real estate as 5 year property. Land itself is never depreciable, so the first step in any study is a defensible allocation between land and building.

How Does Bonus Depreciation Change the Value of a Study?

Bonus depreciation is what turns a cost segregation study from a timing tweak into a large first-year deduction. Under IRC Section 168(k), property with a recovery period of 20 years or less is eligible for bonus depreciation. Every 5, 7, and 15 year component a study identifies falls inside that limit.

The OBBBA permanently restored 100 percent bonus depreciation for qualified property acquired and placed in service after January 19, 2025. Property acquired under a written binding contract signed before January 20, 2025 keeps the old phase-down: 40 percent for property placed in service in 2025 and 20 percent in 2026. Used property counts, as long as you did not use it before and you bought it from an unrelated seller. Our bonus depreciation guide covers the acquisition-date rules in detail.

How Much Can a Cost Segregation Study Save?

The year-one deduction depends on how much of the building the study reclassifies, and that share varies by property. Here is a worked example using a residential rental placed in service in June 2026.

The study does not create new deductions. It moves deductions you would have taken over 27.5 years into the first year. The value comes from using the money sooner and from deducting it in a year when your marginal rate is high.

Can You Use the Loss Against Other Income?

Most rental owners cannot use a large depreciation loss against wages or business income in the year it is created. Under IRC Section 469, rental activities are passive by default, and passive losses only offset passive income. Unused losses carry forward and are released when you sell the property in a fully taxable transaction.

Three paths let the loss reach nonpassive income:

• The $25,000 allowance. Owners who actively participate can deduct up to $25,000 of rental losses. It phases out between $100,000 and $150,000 of modified adjusted gross income.
• Real estate professional status. You need more than 750 hours in real property trades or businesses in which you materially participate, more than half your working time there, and material participation in the rental. See our real estate professional status guide.
• The short-term rental exception. If the average guest stay is seven days or less and you materially participate, the activity is not a rental activity under the passive rules. Our short-term rental guide covers the hours and records.

Even when the loss is nonpassive, the excess business loss limit under Section 461(l) caps how much net business loss can offset other income in one year. The excess becomes a net operating loss carryforward.

Can You Do a Cost Segregation Study on a Property You Already Own?

Yes. A look-back study on a property placed in service in an earlier year catches up all the missed depreciation in the current year, with no amended returns. You file Form 3115, Application for Change in Accounting Method, using the automatic change for a move from an impermissible to a permissible method of depreciation in section 6.01 of Rev. Proc. 2025-23 (designated change number 7).

The catch-up is a negative Section 481(a) adjustment, and a negative adjustment is deducted entirely in the year of change. It equals the difference between the depreciation you claimed and the depreciation allowable under the correct lives, including bonus depreciation on components that qualified when the property was placed in service. A property bought before January 20, 2025 is measured under the bonus rate in effect for its own placed-in-service year.

An impermissible method generally becomes a method of accounting only after you use it on two consecutive returns. If you placed the property in service last year and have filed just one return, you can choose between amending that return and filing Form 3115.

What Happens to the Deductions When You Sell?

The deductions a study accelerates come back as depreciation recapture when you sell. Personal property components are Section 1245 property, so every dollar of depreciation on them, including bonus, is recaptured at ordinary income rates up to 37 percent. Land improvements are Section 1250 property; depreciation above straight-line is recaptured as ordinary income, and the straight-line portion is unrecaptured Section 1250 gain taxed at up to 25 percent.

That recapture is the real cost of a study, and it is why holding period matters. A 1031 like-kind exchange can defer gain on the building and land improvements. The 5 and 7 year personal property components are not like-kind real property, so Section 1245 recapture on them can be taxed in the year of the exchange. Holding the property until death gives heirs a stepped-up basis that removes the recapture. Our depreciation recapture guide walks through the Form 4797 reporting.

A study also helps during ownership. When you replace a component the study identified, such as a roof section or an HVAC unit, a partial disposition election lets you deduct the old component's remaining basis in the year you replace it.

What Makes a Cost Segregation Study Hold Up in an Audit?

The IRS Cost Segregation Audit Techniques Guide describes what examiners look for, and it favors detailed engineering studies over rule-of-thumb percentages. A strong study is prepared by someone with construction or engineering expertise, uses blueprints or a site inspection, ties every component back to the property's actual cost basis, and explains why each item is personal property under the tax law.

Practical checkpoints before you rely on a study:

1. The land allocation is supported by an appraisal or assessor ratio.
2. The component totals reconcile to the purchase price and closing costs.
3. Each asset class on the report matches the depreciation schedule on Form 4562.
4. The study is dated and kept with the property's basis records for as long as you own the property, plus the limitations period after the sale year.

Does Your State Follow Federal Bonus Depreciation?

Many states, including California, do not follow federal bonus depreciation. California does not conform to Section 168(k), so the California return depreciates the same reclassified components over their regular lives. A study still helps on a nonconforming state return through shorter lives, but the first-year state deduction is far smaller than the federal one, and you will track two sets of depreciation schedules.

When Is a Cost Segregation Study Worth It?

A study generally makes the most sense when the building basis is large, you plan to hold the property for several years, and you can use the loss now or soon. The case is weaker for a small single-family rental with a modest basis, a property you expect to sell within a year or two, or an owner whose passive losses will stay suspended for a long time.

Before ordering one, compare the study fee to the present value of the accelerated deductions, net of the recapture you expect on sale. Our cost segregation service coordinates the engineering study with the return, the Form 3115, and the passive loss planning, so the deduction lands in a year you can actually use it.