How Cost Segregation Works: A Step-By-Step Guide With A Worked Example
Daria Pohrebniak
Marketing Director - Reverb
10.17.2026
Cost segregation is a tax planning tool that speeds up depreciation on real estate. Instead of depreciating an entire building over 27.5 years (residential rental) or 39 years (commercial), a study identifies the parts of the property that the tax rules allow to be depreciated faster, over five, seven or fifteen years.
The result is larger deductions in the early years of ownership. With 100% bonus depreciation restored for qualifying property acquired after January 19, 2025, many of those faster components can be deducted in full in the first year. This guide explains how it works and walks through an example.
This guide is general information for investors, not tax or legal advice. Tax rules change and depend on your facts, so confirm any strategy with a qualified CPA or tax attorney before acting on it.
The Asset Classes
Recovery Period
Typical Components
Bonus Eligible
5-year
Appliances, carpet, furniture, decorative lighting, some cabinetry and finishes, dedicated electrical
Yes
7-year
Certain furniture and fixtures, often in commercial or hospitality property
Yes
15-year
Land improvements: paving, sidewalks, landscaping, fencing, site lighting, outdoor recreation features
Yes
27.5-year
Residential rental building structure and its core systems
No
39-year
Nonresidential building structure and its core systems
No
Not depreciable
Land
No
Exact classifications depend on the property and the asset class guidance the IRS uses. A quality study documents each classification so it can be defended.
How A Study Is Done
Step 1: Establish The Basis
The study starts with the purchase price or construction cost and allocates part of it to land, which is never depreciable. Closing costs and capital improvements are added to the depreciable basis.
Step 2: Identify And Measure Components
Engineers or trained analysts identify the building’s components using drawings, photos, cost records and, depending on the provider, a site visit, a virtual walkthrough or public records.
Step 3: Assign Costs
Each component is costed, typically using construction cost data or actual cost records, and assigned to a recovery period.
Step 4: Deliver The Report
The report sets out the methodology, the asset schedule by class and a depreciation schedule your CPA can use. Some providers also deliver a fixed asset file and a Section 481(a) schedule for look-back studies.
A Worked Example
Suppose an investor buys a single-family rental for $600,000 and allocates $120,000 to land, leaving a building basis of $480,000. A study reclassifies 25% of the building basis, or $120,000: $84,000 into 5-year property and $36,000 into 15-year land improvements. The remaining $360,000 stays as 27.5-year property.
Scenario
Approximate First-Year Depreciation
No study: $480,000 over 27.5 years
About $17,500
With study and 100% bonus: $120,000 deducted in year one, plus $360,000 over 27.5 years
About $133,000
This example uses a simplified full-year calculation. Real returns apply the mid-month convention to the building, and results depend on the study, placed-in-service date and eligibility for bonus depreciation. Whether the extra deduction saves tax now depends on whether your losses are passive; see our guides to the short-term rental tax loophole and real estate professional status.
Look-Back Studies
If you bought a property in an earlier year and never had a study, you do not need to amend old returns. A look-back study lets your CPA claim the missed depreciation in the current year through an automatic change in accounting method, filed on Form 3115, with a Section 481(a) adjustment.
Renovations And Improvements
Studies can also break down renovation and improvement costs, which often include a high share of short-lived components such as flooring, cabinetry and appliances. When components are replaced, a partial disposition election may let you write off the remaining basis of what was removed.
State differences: some states, including California, do not follow federal bonus depreciation.
Weak studies with thin documentation are harder to defend if questioned.
What A Study Costs
Prices range from about $495 for software and remote residential reports to $12,000 or more for full engineering studies on large properties. Our guide to cost segregation study costs breaks this down.
Yes. It is an accepted practice, and the IRS publishes an Audit Techniques Guide describing what a quality study looks like.
Does cost segregation increase audit risk?
A study itself does not trigger an audit, but large deductions draw attention to the documentation behind them. A well-documented study built to the IRS guidance is the best protection.
Can I do cost segregation on a primary residence?
No. Depreciation applies to property used in a business or held for the production of income, such as rentals. A home office or rented portion may be different; ask your CPA.
When should I order a study?
Ideally in the year the property is placed in service, so the deduction can be claimed on that year’s return. Look-back studies are available for earlier purchases.
