Under standard tax rules, an entire rental property is depreciated evenly over 27.5 years (residential) or 39 years (commercial). A cost segregation study — performed by a qualified engineering firm — breaks the property into its component parts and reclassifies a significant portion (often 20%–40% of the building's cost) into shorter-life categories: 5-year property (carpeting, certain fixtures, appliances), 7-year property (furniture, certain equipment), and 15-year property (land improvements such as sidewalks, landscaping, and parking lots). These shorter-life components can then be depreciated — and with bonus depreciation, often expensed — far faster than the building itself.
Engage a qualified cost segregation engineering firm
A cost segregation study requires specialized engineering expertise — not just accounting. The firm conducts a detailed physical inspection and cost analysis of the property, often using IRS-approved methodologies (the "detailed engineering approach" is the gold standard recognized by the IRS).
Components are identified and reclassified
The study identifies and itemizes every component of the property — flooring, lighting fixtures, plumbing fixtures specific to tenant use, decorative elements, parking lots, landscaping, fencing, and more — and assigns each to its correct IRS-defined depreciation category based on established case law and IRS guidance (primarily derived from the Investment Tax Credit rules under former IRC Section 48).
Accelerated depreciation — and bonus depreciation — applied
Once reclassified, the 5, 7, and 15-year components qualify for accelerated depreciation under MACRS, and critically, for bonus depreciation — which allows a large percentage of the cost to be deducted immediately in the year placed in service, rather than spread over the shorter life.
Form 3115 filed if applied retroactively
Cost segregation can be applied to a property already owned for years — not just new acquisitions. This requires filing Form 3115 (Change in Accounting Method), which allows you to capture the cumulative "catch-up" depreciation that should have been taken in prior years as a single deduction in the current year — without amending past tax returns.
| Category | Recovery period | Examples |
|---|---|---|
| 5-year property | 5 years | Carpeting, certain decorative fixtures, specialty electrical for equipment, removable wall coverings |
| 7-year property | 7 years | Furniture, certain free-standing equipment, office equipment used in the building |
| 15-year property | 15 years | Land improvements — sidewalks, parking lots, landscaping, fencing, exterior lighting |
| Residential building structure | 27.5 years | The building shell, roof, foundation, structural walls for residential rental property |
| Commercial building structure | 39 years | The building shell, roof, foundation, structural walls for commercial property |
Illustrative example — the tax impact
purchase price
to 5/7/15-yr (25%)
deduction with bonus depr.
For a $2,000,000 commercial property, a cost segregation study might reclassify approximately 25% ($500,000) into shorter-life categories. With 60% bonus depreciation available in 2024, a substantial portion of that reclassified amount can be deducted in year one — compared to the standard straight-line approach which would spread the entire $2,000,000 over 39 years (roughly $51,000/year). The acceleration can defer significant tax liability into future years, freeing up capital today.
⚠️ Depreciation recapture — the trade-off to understand
Cost segregation does not eliminate taxes — it accelerates the timing of deductions. When the property is eventually sold, the accelerated depreciation is subject to depreciation recapture, taxed at a maximum rate of 25% for real property (Section 1250 property) versus ordinary capital gains rates. The strategy works best for investors who plan to hold long-term, use a 1031 exchange to defer the recapture, or use an Asset Diversification Trust structure to defer gains entirely at sale.
Bonus depreciation phase-down — timing matters
Bonus depreciation was 100% through 2022, then began phasing down: 80% in 2023, 60% in 2024, 40% in 2025, 20% in 2026, and 0% in 2027 under current law (absent Congressional extension). The sooner a cost segregation study is completed and property placed in service, the larger the immediate first-year deduction available. This creates real urgency for investors considering the strategy.
Cost segregation + Asset Diversification Trust — a powerful combination
Cost segregation accelerates depreciation deductions during ownership — but eventually, depreciation recapture and capital gains come due at sale. For investors who want to sell an appreciated, heavily depreciated property without an immediate tax event, the Asset Diversification Trust (DST) structure defers both the capital gains and the depreciation recapture across an installment period — compounding the benefit of the upfront cost segregation deduction with deferred taxation at exit. Together, these two strategies span the entire ownership lifecycle: accelerated deductions going in, deferred taxation coming out. Read: Asset Diversification Trust →