Cost segregation is a tax strategy that breaks a building into its separate parts so you can depreciate some of them faster. Items like flooring, appliances, and parking lots get written off over 5, 7, or 15 years instead of 27.5 or 39. That means bigger 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.
The simple idea behind cost segregation
Think about buying a used car. You wouldn't expect the tires to last as long as the engine block. They wear out faster, so you'd plan to replace them sooner.
Buildings are the same. When you buy a property, you're really buying many things at once:
- The structure itself (walls, roof, foundation)
- Things inside it (carpet, appliances, cabinets, light fixtures)
- Things outside it (driveway, fencing, landscaping, parking lot)
The IRS lets you deduct the cost of property over time. This is called depreciation. By default, a whole rental building is depreciated slowly, over 27.5 years for residential or 39 years for commercial. But the tax code says many parts of a building wear out faster and deserve shorter lives.
Cost segregation is the process of finding those faster-wearing parts and separating, or "segregating," their cost from the rest of the building.
What does "segregation" mean here?
In this context, segregation just means separating or sorting. A cost segregation study sorts a building's total cost into groups:
| Group | Depreciation period | Examples |
|---|---|---|
| Personal property | 5 or 7 years | Carpet, appliances, cabinets, some lighting and wiring |
| Land improvements | 15 years | Parking lots, sidewalks, fences, landscaping |
| Building structure | 27.5 or 39 years | Walls, roof, framing, main plumbing and HVAC |
| Land | Not depreciable | The dirt underneath |
Why would anyone do this?
Because of timing. Taking deductions sooner means paying less tax sooner. That gives you more cash today to pay down debt, make repairs, or buy another property.
The benefit got much bigger in 2025. Parts with lives of 20 years or less can qualify for bonus depreciation, and a 2025 law restored bonus depreciation to 100% permanently for property acquired after January 19, 2025. So the 5-, 7-, and 15-year parts identified in a study can often be deducted in full in the first year.
A quick example
Say you buy a rental building for $900,000. The land is worth $150,000, so the building is $750,000.
- Without cost segregation: You'd deduct about $27,000 a year for 27.5 years.
- With cost segregation: A study finds $180,000 of 5- and 15-year property. With 100% bonus depreciation, you could deduct about $180,000 plus regular depreciation on the rest in year one.
Same building, same total deductions over time. The difference is when you get them.
Is there a catch?
A few things to know:
- You may pay some back later. When you sell, depreciation you took can be "recaptured" and taxed.
- You need to be able to use the deduction. Rental losses are often limited by passive activity rules.
- It costs money. A professional study usually costs a few thousand dollars.
- It must be done well. The IRS has a full audit guide on cost segregation studies.
Frequently asked questions
Is cost segregation only for big commercial buildings?
Is cost segregation the same as bonus depreciation?
Do I need a study to use cost segregation?
See what your property may qualify for
Run our 2-minute STR Qualification Quiz or model your Low / Mid / High cost segregation range.
Related guides
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Read guideWhat Is Cost Segregation in Real Estate? A Rental House Walkthrough
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Read guideHow Cost Segregation Changes Your Depreciation
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Read guideWhat Is Bonus Depreciation? A Simple Explanation
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Read guideThis content is not tax or financial advice for you. Please talk with a CPA to find what's right for your situation.