Cost segregation calculator — estimate Year-1 tax savings in 60 seconds.
Pick a property type, enter a purchase price, set your bracket. We use the same industry-standard 2026 construction cost data and IRC §168(k) framework as the engineered study itself — so the estimate reflects what an actual report would conclude, not a sales pitch. New to the topic? Start with what a cost segregation study is.
This free cost segregation calculator (also searched as a cost segmentation calculator or cost seg tool) estimates the Year-1 federal tax benefit you'd get from a cost segregation study on your specific property. The calculator applies a property-type-specific reclassification percentage (16–35% of depreciable basis depending on property type) and 100% bonus depreciation under OBBBA to produce a Year-1 deduction and tax-savings estimate. The underlying math matches the engineered study itself — same industry-standard 2026 construction cost basis, same MACRS framework per Rev. Proc. 87-56. Use this cost segregation study calculator as a "is it worth ordering?" decision tool; the actual study refines the number with regional cost multipliers and component-level analysis.
How the estimate is built.
We start with the building's depreciable basis (purchase price minus an assumed land allocation — 20% residential, 15% commercial), then apply a property-type-specific reclassification percentage based on aggregate component data from completed studies. That reclassified portion is fully deductible in Year 1 under 100% bonus depreciation (OBBBA, signed July 2025). Multiplying by your federal bracket gives the estimated cash benefit.
Real reports vary with property age, condition, geography (regional construction cost multipliers), and finish-level — an actual study can be 10–20% above or below the calculator's estimate. The calculator is intended as a decision tool ("is this big enough to be worth ordering?"), not a substitute for the engineered analysis.
Modeling the deduction rate itself? Use the bonus depreciation calculator to see how the first-year bonus rate applies to your reclassified basis.
Cost segregation calculator FAQ
Is this cost segregation calculator free?
Yes. No signup, no email required to use. The calculator runs entirely in your browser — enter property type, purchase price, and bracket and the Year-1 estimate appears immediately.
How accurate is the cost segregation calculator?
Within 10–20% of the engineered study result for typical residential properties. The calculator uses aggregate reclassification percentages from completed Cost Seg Smart studies. The actual engineered study refines the number with property-specific component analysis, regional construction cost multipliers, finish-level adjustments, and a 16-check QC gate.
What's the difference between this calculator and a real cost segregation study?
The calculator gives a property-type-bucket estimate in 60 seconds. The engineered study produces a 40+ page CPA-ready PDF with component-level MACRS classification per Rev. Proc. 87-56, audit documentation aligned to the IRS Cost Segregation Audit Techniques Guide (Pub 5653), and a Form 3115 §481(a) section for lookback studies — fileable directly on your tax return.
Does the calculator work for short-term rentals (STR) and Airbnb?
Yes. Short-term rental (STR) is one of the property types and uses a higher accelerated reclassification band (19–39%) consistent with the FF&E intensity in furnished properties. Combine with the STR loophole (7-day average stay + material participation) to offset W-2 income, not just passive rental income.
Is this the same as a cost segmentation calculator or cost seg tool?
Yes. "Cost segmentation" is a common misspelling of cost segregation, and "cost seg tool," "cost segregation study calculator," and "cost segmentation calculator" all describe this same free tool. It estimates the Year-1 federal tax benefit of a cost segregation study on your property. There is no separate cost segmentation calculator.
Does this cost segregation calculator follow IRS guidelines?
The estimate uses the same MACRS framework the IRS recognizes (Rev. Proc. 87-56) and reclassification percentages consistent with the IRS Cost Segregation Audit Techniques Guide (Pub 5653). It is an estimate, not a study. The full engineered study is the detailed, component-by-component report your CPA uses to file.
I bought my property years ago and have been using straight-line depreciation. What can I claim now?
You can still do a cost segregation study, and you do not amend any old returns. The depreciation you missed is claimed all in the current tax year as a §481(a) catch-up adjustment, filed on Form 3115 as an automatic change in accounting method. The catch-up is roughly what the study would have allowed through last year minus the straight-line depreciation you already took, and for property placed in service after September 27, 2017 and before 2023 it includes bonus depreciation at the rate that applied in the year the property was placed in service. The exact figure depends on the study, and your CPA files the Form 3115 with your return.