Turning Your Old House Into a Rental or Airbnb: The Tax Mechanics
The move-up-and-keep-it play is everywhere, and so are its basis mistakes. Four rules govern the whole conversion, and none of them are intuitive.
A guide by Taxstra Tax & Accounting · CPA-led tax strategy for business owners
Written by Bryan Martin, CPA, Managing Partner and Founder of Taxstra. Last updated August 19, 2026.
The short answer
Four rules run the whole conversion. Basis: you depreciate the lesser of your adjusted cost or the fair market value on conversion day (building only, land never). Timing: depreciation starts when the home is genuinely listed and available as a rental. The exit window: live-then-rent preserves the Section 121 exclusion for roughly three years after you move out, the friendly direction of a rule that punishes rent-then-live. Losses: a special dual-basis rule stops you from deducting the value your home lost while you lived in it. Get those four right and everything else, including cost segregation on the conversion basis, is ordinary rental tax.
The conversion-day snapshot: build it once, use it for decades
Everything downstream, thirty years of depreciation, the recapture math at sale, any cost segregation study, keys off numbers you establish on conversion day. The file takes an afternoon to build and is miserable to reconstruct later:
- Adjusted basis: purchase price plus documented improvements over the years (the remodel receipts you swore you would keep), allocated between land and building.
- Fair market value at conversion: an appraisal or solid comparable analysis dated near the conversion. This is the number that caps your depreciable basis if the home has declined, and proves your basis if values rose.
- Placed-in-service evidence: the listing going live, market-rate pricing, availability records, the same standard covered in the placed-in-service guide.
2018 house, $400K cost, converting to an Airbnb in 2026 (illustrative)
- Original cost + $45K of documented improvements
- $445,000 adjusted basis
- FMV at conversion (appraised)
- $610,000
- Depreciable figure: LESSER of the two, minus land ($95K)
- $350,000 building basis
- Cost seg on the conversion basis: ~25% to short-life classes
- about $87,000 of components
- If run as a qualifying STR with material participation
- the accelerated deduction can offset W-2 income
Note what did NOT happen: the $165K of appreciation while it was a residence added nothing to depreciation. Conversions depreciate history, not headlines. Illustrative numbers; the land split and the study drive the real ones.
The exit math: conversions have a golden window
Because Section 121 asks for two years of residence within the five years before sale, a converted home keeps its exclusion for roughly three years of renting after you move out, and renting after residence generally avoids the nonqualified-use haircut that ruins the reverse order. That creates a genuine strategy corridor: convert, run the rental (even an aggressive STR year with cost segregation), and if you sell inside the window, exclude up to $250K/$500K of the appreciation while paying tax only on the depreciation taken. Miss the window by a month and the exclusion is gone entirely. The rent-first mirror image, and why it fails, is covered in the move-in-then-sell guide.
The declining-market conversion is a basis trap in both directions
The conversion-year return itself deserves a walkthrough, because it is where good conversions get filed badly. Your preparer needs to establish the depreciation schedule correctly ONCE: building basis from the lesser-of rule, land carved out, a 27.5-year residential life starting at the placed-in-service date, and any cost segregation allocations layered on top of that same conversion basis. Improvements made to ready the property for guests, the new flooring, the mini-splits, the furniture, go on the schedule as their own assets with their own lives, and the furniture and appliances are exactly the five-and-seven-year property that bonus depreciation eats immediately. Meanwhile the personal-period expenses stay on Schedule A, the rental-period share moves to Schedule E, and the household's withholding usually deserves a mid-year look because the property just swung from costing after-tax money to generating deductions. None of this is exotic; all of it is easy to set up wrong in software that assumes properties are purchased, not converted, and a wrong first-year schedule quietly compounds for twenty-seven years.
Converting this year? Get the basis file built on day one.
Walk us through your situation and we'll tell you how we can help. 30 minutes, free, no pressure.
Frequently Asked Questions
What is my depreciation basis when I convert my home to a rental?
The LESSER of your adjusted basis (what you paid plus improvements, for the building portion) or the fair market value on the conversion date. In appreciating markets that is usually your original cost, not today’s higher value. You do not get to depreciate appreciation that happened while it was your residence.
When does depreciation start on a converted rental?
When the property is placed in service as a rental: ready, available, and genuinely held out for rent, typically the listing date, not the day you moved out and not the day the first tenant or guest arrives. From that date, the building depreciates over 27.5 years on the conversion-date basis, land excluded.
Can I still use the Section 121 exclusion if I rent my old home for a while before selling?
Often yes: the exclusion requires two years of ownership and use as your principal residence within the five years before sale, so roughly up to three years of renting after moving out can preserve it. Gain attributable to post-1997 depreciation is never excludable, and the friendly ordering here (live first, then rent) is the opposite of the rent-first pattern that triggers nonqualified-use haircuts.
Does a cost segregation study work on a converted property?
Yes. The study allocates your conversion-date depreciable basis among 5, 7, 15, and 27.5-year classes, and the shorter-life components qualify for bonus depreciation based on the conversion-year rules. A 2018 house converting to an Airbnb this year runs cost seg on the conversion basis; the deduction is smaller than a fresh purchase at today’s prices, but the mechanics are identical.
What happens if I sell the converted rental at a loss?
Loss on sale uses a special dual-basis rule: for computing LOSS, your starting point is the lesser-of-basis-or-FMV at conversion (reduced by depreciation). This prevents converting a personal decline in value into a deductible rental loss. Homes converted after big price drops need this modeled before assuming the loss is usable.
How do mortgage interest and property taxes split in the conversion year?
By time: the months as your residence follow the personal rules (itemized deduction for interest within the home-acquisition limits, property taxes inside the SALT cap), and the months as a rental deduct in full on Schedule E with no caps. The conversion date is the hinge, one more reason to document exactly when the property became available for rent.
Do I need a formal appraisal at conversion, or is an online estimate enough?
The rules require fair market value, not a specific document, but what you are really buying is defensibility decades from now. An appraisal dated near the conversion is the gold standard; a broker price opinion or a well-documented comparable analysis is a workable second. A screenshot of an algorithmic estimate is what people bring to exams they lose.
What if I move back into the rental later?
Conversion runs in both directions: moving back in stops the depreciation and restarts residence use, and a later sale mixes the periods under the Section 121 rules, with post-2008 rental periods after your original residence generally NOT counting as nonqualified use, but depreciation always taxable. Multi-conversion histories are exactly the files where a year-by-year timeline pays for itself.
Related Questions
Convert With the Paper Trail Future-You Will Need
Book a free 30-minute call to walk through your situation. We'll tell you exactly how our CPA-led team can help, and whether we're the right fit.
What to Expect on the Call
This page is educational, not individualized tax advice. Outcomes depend on your specific facts and documentation. Savings vary by client and results are not typical of every situation. Consult a qualified tax professional before acting on anything here.