Cost Segregation Calculator
Most rental investors leave 60–80% of the available year-1 depreciation on the table. Cost segregation accelerates the deductions an engineer-led study could find. This calculator estimates the year-1 lift before you commission a real study.
Property & Study Inputs
A cost segregation study reclassifies portions of a building from 27.5-year property to 5/7/15-year property — accelerating depreciation.
Most studies move 20–35% of building basis to 5/7/15-year property.
2026 phase-down rate. Was 100% pre-2023; check the current year.
Year-1 Tax Savings
estimated year-1 tax savings (vs. regular depreciation)
A real cost segregation study costs $5,000–$15,000 and requires an engineer-led property inspection. This is a rough estimate to gauge whether a study is worth commissioning.
Analyze a real propertyHow cost segregation works
A standard residential rental depreciates straight-line over 27.5 years — about 3.6% per year. A cost-seg study breaks the building into components: 5-year (fixtures, carpet, appliances), 7-year (specialized equipment), 15-year (land improvements), and 27.5-year (the structure). The short-life buckets become bonus-depreciable, meaning a huge first-year deduction.
The math
Frequently asked questions
What is cost segregation?
Cost segregation is an engineering-led tax study that breaks a building into its components and reclassifies portions from 27.5-year property to 5/7/15-year property. Combined with bonus depreciation, this lets investors take a much larger first-year deduction than straight-line allows.
What can be reclassified?
Carpet, flooring, cabinetry, fixtures, appliances → 5-year. Site improvements (driveway, parking, fencing, landscaping) → 15-year. Plumbing/electrical specific to specialized use → 7-year. The structure (walls, roof, HVAC core) stays at 27.5/39 years.
How much is reclassified?
Typically 20–35% of the building basis depending on property type. Single-family rentals: ~15–25%. Apartments/multifamily: ~25–35%. Commercial/retail: ~30–40%. Industrial: ~25–30%. The exact number requires an engineer-led study.
What is bonus depreciation?
A first-year deduction that lets you write off the full reclassified basis immediately. Bonus depreciation was 100% from 2018–2022, then phased down: 80% in 2023, 60% in 2024, 60% in 2025 (after extension), and 60% in 2026. Verify the current year before underwriting.
How much does a cost segregation study cost?
$5,000–$15,000 for residential, $10,000–$30,000+ for commercial. Most studies pay for themselves in the first year if the property is over $400,000. Below that threshold, the math is closer — get a free preliminary analysis from a study firm.
Can I do cost seg on a property I bought years ago?
Yes — it’s called a "look-back" study. Form 3115 lets you catch up on missed deductions in a single year (a one-time large deduction). Particularly powerful for properties bought during high bonus-depreciation years (2018–2022).
What happens at sale?
Reclassified short-life property recapture is at ordinary income rates (up to 37%), vs. straight-line residential recapture capped at 25%. So cost seg can mean higher tax at exit — but the time-value benefit of accelerating deductions usually wins. A 1031 exchange defers recapture entirely.
Is cost segregation a red flag for the IRS?
No — it’s an established and IRS-recognized practice. The IRS publishes the Cost Segregation Audit Techniques Guide. As long as your study is engineer-led and properly documented, it’s a normal tax planning tool.
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