Real Estate Tax Calc
What it does
A cost segregation study has an engineer identify building components that qualify as shorter-life property (5-, 7-, and 15-year assets) instead of the standard 27.5 or 39 years. Those components depreciate much faster, and bonus depreciation can pull a large deduction into year one.
Is it worth the fee?
Studies cost money, so they pay off best on higher-basis properties where the accelerated deduction — and the time value of the tax savings — clearly exceed the fee. Use the calculator to estimate first-year savings before commissioning one.
The recapture tradeoff
Accelerated depreciation increases the amount subject to recapture when you sell, and some of it becomes ordinary-income (Section 1245) recapture. A 1031 exchange can defer that.
What the study actually reclassifies
Standard depreciation lumps almost everything into the 27.5-year (residential) or 39-year (commercial) building bucket. A cost segregation engineer breaks the building apart and moves qualifying pieces into faster classes: 5-year property (carpeting, appliances, decorative lighting, cabinetry, dedicated electrical or plumbing that serves specific equipment), 7-year property (certain furniture and fixtures), and 15-year land improvements (parking lots, sidewalks, fencing, landscaping, site lighting, and retaining walls).
On a typical residential rental, 15%–30% of the depreciable basis can shift into these shorter classes; on hotels, restaurants, and retail with heavy build-outs, it can exceed 40%. Only the underlying land never depreciates — and it's excluded from basis entirely.
Why the timing of deductions matters — the time value of money
Cost segregation doesn't create more total depreciation; you'd eventually deduct the same building cost either way. What it does is pull deductions forward. A dollar of tax saved this year is worth more than a dollar saved in year 25, because you can reinvest it now. This is the whole economic engine: the study converts a slow trickle of deductions into a front-loaded flood, and the present value of that acceleration is what you're buying for the study fee.
With 100% bonus depreciation available again on 20-year-or-less property (permanently restored under the One Big Beautiful Bill Act, per IRS Notice 2026-11), every dollar reclassified into 5-, 7-, or 15-year property can be deducted in year one — making the acceleration more dramatic than during the phase-down years.
A worked example with real figures
You buy a residential rental for $1,000,000 and allocate $200,000 to land, leaving an $800,000 depreciable basis. Without a study, first-year depreciation is roughly $800,000 ÷ 27.5 ≈ $29,000. Commission a study, and suppose it reclassifies 25% ($200,000) into bonus-eligible short-life property. With 100% bonus, that $200,000 is deductible immediately; the remaining $600,000 depreciates over 27.5 years (~$21,800). First-year depreciation jumps to roughly $221,800.
At a 32% marginal rate, that's about $71,000 of first-year tax savings versus $9,300 without the study — an extra ~$62,000 in year one. If the study cost $6,000, the payback is immediate and overwhelming. Enter your own numbers in the calculator to see how the reclassified percentage and your rate change the result.
When it's worth it — and when it isn't
Cost segregation pays off best when several things line up: a higher-basis property (the fee is roughly fixed, so more basis means more benefit), a high marginal tax rate so deductions are worth more, and an intent to hold for several years so recapture doesn't immediately claw the benefit back.
It's often not worth it on a low-basis single-family rental where the study fee eats much of the savings, when you expect to sell within a year or two, or — critically — when passive activity loss rules prevent you from using the deductions. If your rental losses are already suspended and you have no passive income to offset, accelerating more paper losses just adds to a carryforward you can't currently use.
The passive activity loss catch
This is the most common disappointment. For most investors, rental real estate is a passive activity, and losses (including a big first-year depreciation loss) can only offset passive income — not W-2 wages or business profits. Unused losses suspend and carry forward, releasing in full when you sell.
The exceptions that unlock the deductions against active income: qualifying as a Real Estate Professional (more than 750 hours and more than half your working time in real property trades, with material participation), or running a short-term rental with average guest stays of seven days or less where you materially participate — which is treated as non-passive. Confirm your situation before assuming a study will offset your salary this year.
Cost, methods, and audit posture
A quality engineered study — the IRS-preferred method described in the agency's Cost Segregation Audit Techniques Guide — typically runs from about $5,000 for a small property to $15,000+ for large commercial buildings. Cheaper "rule of thumb" or DIY allocations exist but carry more audit risk and less defensible documentation. For a property you've owned for years, you don't have to amend prior returns: you can "catch up" all the missed accelerated depreciation in the current year via an automatic accounting-method change on Form 3115, claiming a §481(a) adjustment. Keep the engineer's report; it's your support if the IRS asks.
Planning tips to maximize the benefit
Time a study for a year when you can actually use the deductions — ideally the acquisition year, or a year you qualify as a real estate professional or run the property as a short-term rental. Pair it with a year of high other income to blunt a large tax bill. If you plan to sell, consider a 1031 exchange to defer the Section 1245 and 1250 recapture the study created. And model the full life cycle — first-year savings, mid-hold depreciation, and eventual recapture — rather than looking only at the headline year-one number.
How a study is actually performed
A quality engineered study follows a repeatable process. The firm reviews your closing statement, appraisal, and construction or renovation records, then conducts a site inspection (or detailed photo review) to identify and measure every qualifying component. Engineers apply cost-estimating methods — sometimes reconstructing original construction costs — to allocate your purchase price across asset classes. The deliverable is a written report that assigns each dollar of basis to its recovery period (5, 7, 15, 27.5, or 39 years), with photos, calculations, and legal citations to support the classifications.
This documentation is what makes the deductions defensible. The IRS's own Cost Segregation Audit Techniques Guide describes the engineering-based approach as the most reliable method, and examiners expect to see that level of support. A back-of-the-envelope allocation without an inspection or engineering basis is far more likely to be challenged.
Property types where the benefit is largest
The reclassifiable percentage varies widely by property type. Apartments and residential rentals typically see 20–30% moved into short-life classes. Retail, restaurants, and medical offices — with heavy tenant build-outs, specialty plumbing, and decorative finishes — can exceed 35–40%. Hotels and self-storage also score high. By contrast, a plain warehouse or raw land-heavy purchase reclassifies less, because more of the value sits in the long-life shell or in non-depreciable land.
This is why the same $6,000 study fee produces wildly different returns depending on what you bought. Before commissioning a study, a reputable firm will give you a free feasibility estimate projecting the likely reclassification and first-year benefit for your specific property.
Interaction with other tax rules
Cost segregation doesn't operate in a vacuum. Its deductions feed into the passive activity loss rules (they may suspend if you're a passive investor), the excess business loss limitation under IRC § 461(l) (which caps how much business loss high earners can use against other income in a year), and at-risk rules that limit losses to the amount you actually have on the line. Bonus depreciation on the reclassified components also reduces your basis dollar-for-dollar, which increases future recapture. None of these is a reason to skip a study — but they explain why the year-one tax savings on paper may differ from what actually lands on your return. A CPA should run the study's output through your full tax picture before you count on the number.
Bottom line: is it worth it for you?
Cost segregation is genuinely valuable, but it isn't universal. It's most worth it when you own a higher-basis property (roughly $500,000+ in depreciable basis is a common rule of thumb, though smaller properties can pencil out), you're in a high marginal bracket, you can actually use the deductions this year (as a real estate professional, a short-term rental operator, or against passive income), and you'll hold long enough that the time-value benefit outweighs the eventual recapture. It's usually not worth it on a small, low-basis rental where suspended losses would just pile up, or if you plan to sell within a year. Get a free feasibility estimate, run your first-year savings through the calculator, and confirm with your CPA that the deductions are usable before you commission a study — that three-step check separates a five-figure win from a wasted fee.
Frequently asked questions
How much can a cost segregation study save?
It depends on the reclassified percentage (often 20–30%), the bonus depreciation rate, and your marginal tax rate. The calculator estimates first-year savings.
When is it worth it?
Usually on higher-basis properties where accelerated deductions outweigh the study cost.
Can I do a cost segregation study on a property I've owned for years?
Yes. You can catch up all the missed accelerated depreciation in the current year using Form 3115 (an automatic accounting-method change with a §481(a) adjustment) — no need to amend prior returns.
Will a cost segregation study help if I can't use passive losses?
Often not right away. For most passive investors the accelerated deductions suspend and carry forward until you have passive income or sell. The benefit is immediate only if you qualify as a real estate professional or run a materially-participated short-term rental.
Does cost segregation increase my taxes when I sell?
It increases the amount subject to depreciation recapture, and some becomes ordinary-rate Section 1245 recapture. You can defer that with a 1031 exchange, and the time-value benefit of the earlier deductions usually still comes out ahead.
Sources
Educational information and estimates only. Not tax advice. Tax rules change and vary by situation; consult a qualified tax professional before acting.