Most landlords depreciate their property over 27.5 years (residential) or 39 years (commercial) on a straight line. A cost segregation study breaks the building into shorter-lived components and accelerates a meaningful portion of that depreciation into the first few years — often producing a six-figure paper loss in year one.
What a cost segregation study actually does
A property isn't a single asset. It's a collection of components — land, structure, plumbing, electrical, flooring, landscaping, parking, signage — each with its own IRS-defined useful life. Cost segregation is the engineering analysis that breaks your purchase price into those buckets and reclassifies as much as possible into the 5-year, 7-year, and 15-year categories instead of the default 27.5 or 39 years.
The reclassified portion can typically be depreciated all at once in year one, thanks to bonus depreciation rules — turning a paper expense into a real tax shield against your rental and (in some cases) your W-2 income.
How big is the year-one deduction?
On a $1,000,000 building basis (excluding land), a study typically reclassifies 15–35% of the basis into short-life buckets. At 60% bonus depreciation (the current phase-down for 2026), that produces a year-one deduction of:
- 20% reclassified × $1,000,000 × 60% bonus = $120,000 deduction in year one
- At a 37% federal bracket: $44,400 in year-one tax savings
- At a 24% federal bracket: $28,800 in year-one tax savings
The exact number depends on the property type, condition, finishes, and the engineer's findings.
When cost segregation makes sense
Cost segregation works best when:
- You hold the property for at least 3–5 years (the longer you hold, the more the accelerated depreciation compounds before recapture)
- Your basis after land is $300,000+ (smaller properties don't generate enough deduction to justify the $5,000–$15,000 study cost)
- You have other passive income or qualify as a real estate professional (so the deductions actually offset taxable income)
- You can use the deductions in the year they're created (don't waste them on a low-income year)
When it doesn't
Cost segregation is not free money — it's a timing strategy. If you sell before the recapture catches up, you owe 25% depreciation recapture tax on every accelerated dollar. The benefit is real, but it's a deferral, not a permanent escape.
It also doesn't make sense if:
- Your basis is too small for the study to pay for itself
- You're planning to sell within 1–2 years and don't intend to 1031 the proceeds
- You're already at $0 taxable income from rentals (no income to offset)
How to figure out if it's worth it
Run a rough number first. Use our free cost segregation estimator — enter your basis and bracket, and you'll see the year-one tax savings in seconds. If the math justifies the study cost, the next step is a 30-minute call with a cost-seg engineer who can confirm the reclassification opportunity for your specific property.