Cost segregation for rental property

A cost segregation study is an engineering-based analysis that splits a building's cost into its parts, so the ones with shorter tax lives (appliances, removable flooring, window treatments, furniture, patios, fencing, landscaping) are depreciated over 5, 7 or 15 years instead of the building's 27.5 or 39. For property acquired after January 19, 2025, those shorter-lived parts can also take 100% bonus depreciation, which turns them into a first-year deduction.

It does not create new deductions. It moves depreciation you would have taken over decades into the first year or two, which is worth a great deal if you can use the losses now and much less if you cannot.

What does a cost segregation study do?

When you buy a rental, the default is to treat everything except the land as one building, depreciated straight line over 27.5 years (39 for nonresidential property). But a purchase price buys more than a structure. It buys appliances, carpet, blinds, light fixtures for specific equipment, a driveway, a fence and the landscaping, and the tax code gives many of those shorter lives.

A cost segregation study assigns a value to each of those components and moves them into their proper classes. The IRS's own audit guide for residential rentals is the best map of where things land:

The guide is written for examiners, not taxpayers, but a study that follows it is on firm ground. A furnished short-term rental usually has more in the 5-year column than an unfurnished long-term rental, which is one reason studies are popular with owners who buy a vacation rental.

How bonus depreciation works in 2026

Bonus depreciation lets you deduct a percentage of a qualifying asset's cost in the year it is placed in service, on top of regular depreciation. It applies to property with a recovery period of 20 years or less, which includes the 5, 7 and 15-year parts a study finds but never the building itself. Used property qualifies if you did not use it before and did not buy it from a related party.

The rate depends on when you acquired the property, which for a purchase means when you signed a binding written contract:

The One Big Beautiful Bill Act, signed July 4, 2025, made the 100% rate permanent for property acquired after January 19, 2025. The IRS's interim guidance (Notice 2026-11, January 2026) confirms the date and lets you elect a 40% rate instead for property placed in service in your first tax year ending after January 19, 2025, or elect out of bonus by class of property. These rules were checked against the IRS's January 14, 2026 release (IR-2026-06), Notice 2026-11 and Publication 946 (2025).

Many states do not follow federal bonus depreciation, California among them, so your state return may spread the same deduction out.

When is cost segregation worth it?

The arithmetic above is only real if the deduction lowers tax you would otherwise pay. Ask these questions before you order a study:

• Can you use the losses now? Rental losses are passive by default and offset only passive income. They become usable against wages or business income if you qualify as a real estate professional, or if the property is a short-term rental with an average stay of seven days or less and you materially participate. Otherwise the loss carries forward, which is still worth something, just later. The short-term rental tax loophole explains the second route.
• Is the building basis large enough? A study for a single-family home commonly costs a few thousand dollars, more for a detailed engineering study, less for a model-based one. Compare the fee with the extra first-year depreciation, not the total.
• How long will you hold it? Sell within a few years and most of the accelerated depreciation is recaptured at ordinary income rates. Hold for many years, or trade into another property through a 1031 exchange, and the deferral is worth more.
• What is your tax rate now and later? Deductions taken at a high bracket and recaptured at a lower one are a win; the reverse is not.
• Is the loss big enough to hit a cap? For 2026, business losses over $256,000 ($512,000 on a joint return) beyond your business income cannot offset other income in the same year, according to the IRS's draft Form 461 instructions; the excess carries forward.

The base layer under all of this is ordinary depreciation, covered in how rental property depreciation works. Model the property's cash flow separately in the deal calculator: a study changes your tax bill, not the rent or the mortgage.

How a study is done, and what makes it hold up

The IRS audit guide describes six ways studies are prepared, from a detailed engineering review of actual construction costs, through engineering estimates, residual estimation and sampling or modeling, down to a "rule of thumb" percentage, which it treats as the weakest. For a purchased home there are no construction invoices, so most studies estimate each component's cost from a site visit, photos, plans and cost databases, then reconcile the total to your basis.

A study that holds up in an examination usually:

• Is prepared by someone whose credentials and experience are stated, typically with engineering or construction cost expertise.
• Describes the method and the site inspection, with photographs.
• Lists each component with its cost, its class and the authority for that class.
• Reconciles the components to the total depreciable basis, with land excluded.
• Treats items like cabinets and permanent flooring the way the IRS's residential rental matrix does, or explains why not.

Model-based reports that use only the address and a few questions cost less and can be reasonable for small properties, but they rest more on assumptions. If a large deduction rides on the study, the documentation is what you are paying for.

Can you do cost segregation on a rental you already own?

Yes. A look-back study on a property placed in service in an earlier year is common. Instead of amending past returns, your CPA files Form 3115 for an automatic change in accounting method and takes all the depreciation you missed as a single catch-up adjustment in the current year. The catch-up generally follows the rules of the year the property was placed in service, including that year's bonus rate, so a rental placed in service in 2023 or 2024 under the phase-down gets less bonus than one bought after January 19, 2025.

Look-back studies make sense when your situation has changed: you now qualify as a real estate professional, you have converted a long-term rental to a short-term one that meets the participation tests (weigh that move with short-term versus long-term renting), or you have passive income from other properties to absorb the loss.

What are the downsides of cost segregation?

• Recapture at sale. Depreciation on the 5 and 7-year parts is recaptured as ordinary income to the extent of the gain on them, and bonus taken on 15-year land improvements counts as additional depreciation, also recaptured at ordinary rates. Only the building's straight-line depreciation gets the 25% maximum rate.
• Passive loss limits. A huge loss you cannot use sits on your return until you have passive income or sell.
• Smaller deductions later. Front-loading leaves less depreciation for the years ahead, when your income might be higher.
• Audit exposure. A large first-year loss invites questions. Keep the study, the basis records and, for the short-term rental route, your hours log.
• Fees and state rules. The fee is certain; the benefit depends on facts. States that decouple from bonus depreciation reduce it further.

General education, not financial, tax or legal advice. Figures are examples: rates, rules and programs change, and every lender sets its own. Last checked November 4, 2026.