What Is a Cost Segregation Study? 10 Quick Answers

By Chirag Gandhi · Short Term Rental Taxes & active STR owner Reviewed by an independent CPA firm · Read bio & methodology →

Guide 17 of 35Cluster guide6 min readOctober 2026

Quick answer

A cost segregation study is a detailed report, usually prepared by engineers or cost specialists, that divides a building's purchase or construction cost into categories with different tax lives. It identifies parts you can depreciate over 5, 7, or 15 years instead of 27.5 or 39 years, so you can claim larger tax deductions sooner.

This content is not tax or financial advice for you. Please talk with a CPA to find what's right for your situation.

Below are the questions property owners ask most often, answered simply.

1. What does a cost segregation study actually produce?

A written report. It lists the building's components, assigns a cost to each one, and groups them by depreciation life. Your CPA uses the report to set up your depreciation schedule.

2. Who prepares the study?

Usually a specialty firm with engineers or construction cost estimators, sometimes working with or inside a CPA firm. The IRS says a quality study should be prepared by someone with real expertise.

3. What kinds of property qualify?

Any building used to produce income or in a business: rentals, short-term rentals, apartments, offices, retail, warehouses, hotels, restaurants, and medical buildings. Your personal home doesn't qualify.

4. How much can it save me?

Most studies move about 15% to 40% of the building's cost into shorter lives. On a $1 million building, that could mean $150,000 to $400,000 of deductions moved into the first year. Your actual tax savings depend on your tax rate and whether you can use the losses.

5. How much does a study cost?

Typically about $2,000 to $15,000, depending on property size and complexity. Large or complex properties can cost more.

6. How long does it take?

Usually two to six weeks from engagement to final report. Plan ahead during tax season.

7. When is the best time to do one?

In the tax year you buy, build, or renovate the property. But you can also do one years later through a look-back study.

8. What if I bought the property years ago?

You can still benefit. A look-back study combined with Form 3115 lets you claim all the depreciation you missed in one year, without amending old tax returns.

9. Is it legal, and will it get me audited?

It's legal and accepted by the IRS. The IRS publishes an audit guide describing what a quality study looks like. A study doesn't automatically trigger an audit, but a weak one is harder to defend.

10. Are there any downsides?

Three main ones:

Depreciation recapture when you sell can tax back some of the benefit.
Passive loss rules may limit when you can use the deductions.
The upfront fee may not pay off for small or short-term holdings.

The bottom line

A cost segregation study doesn't create new deductions. It moves them earlier, which puts cash in your pocket now. For many owners of income property, especially with 100% bonus depreciation now permanent for property acquired after January 19, 2025, that timing difference is worth tens of thousands of dollars.

Frequently asked questions

What does a cost segregation study actually produce?

A written report listing the building's components, assigning a cost to each one, and grouping them by depreciation life for your CPA.

What if I bought the property years ago?

A look-back study combined with Form 3115 lets you claim all the depreciation you missed in one year, without amending old tax returns.

Is it legal, and will it get me audited?

It's legal and accepted by the IRS. The IRS publishes Publication 5653 describing what a quality study looks like.

See what your property may qualify for

Run our 2-minute STR Qualification Quiz or model your Low / Mid / High cost segregation range.

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