Real Estate Tax Calc
The conversion basis rule
When you convert your primary residence to a rental, your depreciable basis is the lower of two amounts: (1) your adjusted cost basis — original purchase price plus improvements minus any prior casualty losses, or (2) the fair market value of the property on the conversion date. You then subtract the land value from whichever figure is lower to arrive at the depreciable building basis.
Example: You bought your home for $220,000 (with $40,000 attributable to land), added $30,000 of improvements, and the FMV is $380,000 when you convert. Adjusted cost basis = $210,000 (building only). FMV at conversion = $340,000 (building only). Depreciable basis = $210,000 — the lower of the two. You do not get to depreciate the $130,000 of unrealized gain.
The placed-in-service date
Depreciation starts on the date the property is available for rent — not the date a tenant moves in. If you finish repairs, list it for rent on September 15, and a tenant moves in October 1, your depreciation clock starts September 15 using the mid-month convention for that month.
Make sure you document the conversion date clearly: listing date, rental listing ads, or property manager engagement letters all work. The IRS has challenged conversions where the property sat vacant with personal belongings still inside.
Section 121 and recapture interactions
The period you lived in the home can still count toward the Section 121 exclusion (up to $250,000/$500,000 of gain) if you sell within five years of conversion — subject to the non-qualified-use rules for any time rented after 2008. Depreciation claimed during the rental period is recaptured at up to 25% and is not sheltered by the Section 121 exclusion.
Why the 'lower of cost or FMV' rule exists
The rule that your depreciable basis is the lower of adjusted cost or fair market value at conversion is not arbitrary — it stops taxpayers from converting a home solely to depreciate paper losses. If the property has declined in value while you owned it as a residence, Congress does not want you claiming a rental deduction for a loss that accrued during personal use (personal losses are not deductible). By capping depreciable basis at the lower FMV, the rule confines your depreciation to value that will actually be consumed during the rental period.
In practice, most homes have appreciated by the time owners convert them, so the adjusted cost basis is the lower figure and controls. But in a declining market — or with a home bought at a peak — FMV can be the lower number, and you must use it. Getting a dated appraisal at conversion protects you either way.
The dual-basis trap when you later sell at a loss
Converted personal residences carry a peculiar dual basis for computing gain or loss on a later sale. For figuring a gain, you use your regular adjusted cost basis (reduced by depreciation). For figuring a loss, your basis is the lower of adjusted cost or FMV at conversion, also reduced by depreciation. If the eventual sale price falls between those two figures, you have neither a deductible loss nor a taxable gain.
Example: adjusted cost basis $300,000, FMV at conversion $260,000, and you later sell for $280,000 after claiming $20,000 of depreciation. Gain basis is $280,000 ($300,000 − $20,000); loss basis is $240,000 ($260,000 − $20,000). Because the $280,000 sale price is above the loss basis but at the gain basis, the result is $0 recognized gain or loss on the operating figures — the depreciation still recaptures separately. This dual-basis mechanic surprises owners who assume a below-purchase-price sale automatically produces a deductible loss.
Establishing fair market value at conversion
Because FMV at conversion can control your depreciable basis and your loss basis, documenting it well is worth the effort. The strongest evidence is a written appraisal from a licensed appraiser dated near the conversion. Acceptable secondary evidence includes a broker's price opinion, a comparative market analysis with genuine comparable sales, or — as a weaker fallback — the county assessor's market value adjusted to true market levels.
Also split that FMV between land and building, since only the building is depreciable. A common method is to apply the land-to-total ratio from the assessor's records to whichever basis figure you use. Keep the appraisal, the land allocation worksheet, and the rental listing permanently — these support both your annual depreciation and your gain/loss computation at sale, which may be many years away.
A step-by-step conversion checklist
1. Compute adjusted cost basis: purchase price + capital improvements − prior casualty losses. 2. Obtain FMV at the conversion date (appraisal preferred). 3. Take the lower of the two. 4. Subtract the land portion to get depreciable building basis. 5. Determine the placed-in-service date (when available for rent). 6. Depreciate the building basis over 27.5 years, straight-line, using the mid-month convention in year one.
7. Report the rental on Schedule E and file Form 4562 for the first year of depreciation. 8. Keep the appraisal, improvement receipts, and listing evidence with your permanent records. Following this sequence prevents the two most expensive errors: depreciating the full current market value (overstating deductions) and forgetting to reduce basis for the land.
Converting back, and planning around the rule
If you later move back into the property, you convert it from rental to personal use again. Depreciation stops, but the depreciation you already claimed remains subject to recapture whenever you ultimately sell in a taxable transaction — moving back in does not erase it. The Section 121 exclusion is also reduced for periods of non-qualified use (generally rental periods after 2008), so alternating between rental and personal use complicates the exclusion math.
Planning tips: if you expect to convert a home to a rental, consider getting the appraisal before you list it for rent so the FMV is contemporaneous. If the home has appreciated substantially and you might sell within three years, weigh selling as a residence to capture the Section 121 exclusion against renting and losing part of the exclusion to non-qualified use. And remember that any depreciation you were entitled to claim is recaptured at sale whether or not you actually claimed it — so there is no benefit to skipping depreciation on a converted home.
What flips from itemized deduction to rental expense
Conversion changes how some costs are deducted, not just whether the building is depreciable. While the property was your residence, mortgage interest and property taxes were itemized deductions on Schedule A (subject to the SALT cap and mortgage-interest limits). Once it becomes a rental, that same mortgage interest and those property taxes move to Schedule E as ordinary rental expenses — fully deductible against rental income and no longer squeezed by the $10,000 SALT cap that applies to personal itemized deductions.
This shift is often favorable: expenses that were partially or wholly lost on Schedule A become fully deductible business expenses. Insurance, utilities you pay, repairs, and management fees — none of which were deductible while you lived there — also become deductible once the property is a rental. Split the year of conversion: costs incurred during personal use follow the personal rules, and costs from the placed-in-service date forward go on Schedule E.
State tax and depreciation conformity
Federal rules govern the lower-of-cost-or-FMV basis and the 27.5-year life, but your state may treat depreciation differently. Most states conform to federal MACRS, but several decouple from bonus depreciation and require add-backs and separate state depreciation schedules. If you cost-segregate a converted home and claim bonus depreciation on shorter-lived components, you may owe state tax on income the federal return shelters, then recover it over time through state-only depreciation.
States also differ on how they tax the eventual sale — some conform to the federal Section 121 exclusion, some tax capital gains as ordinary income, and a few have no income tax at all. Because a converted rental can be held for many years and sold long after conversion, keeping both a federal and (where different) a state depreciation schedule from day one avoids painful reconstruction later. When you own rentals across state lines, each state's conformity rules apply to that property.
Frequently asked questions
What basis do I use for depreciation on a converted home?
The lower of your adjusted cost basis or the fair market value on the date of conversion, minus land in either case.
When does depreciation start on a converted home?
On the date the property is ready and available for rent — not when a tenant actually moves in.
Do I get credit for appreciation when calculating depreciation?
No. If your home appreciated before conversion, that appreciation does not increase your depreciable basis. You lose those gains to the lower-of-cost-or-FMV rule.
Can I deduct a loss if I sell a converted rental below what I paid?
Not necessarily. Converted residences have a dual basis: loss is measured against the lower of adjusted cost or FMV at conversion (less depreciation). If the sale price falls between the loss basis and the gain basis, you recognize neither a deductible loss nor a gain.
How do I prove fair market value at the conversion date?
A written appraisal from a licensed appraiser dated near the conversion is the strongest evidence. A broker price opinion or comparative market analysis with real comps can support it. Keep the documentation permanently, since it affects both annual depreciation and your gain/loss calculation at sale.
Does moving back into the property erase the depreciation I claimed?
No. Depreciation stops when personal use resumes, but the depreciation already taken is still recaptured at up to 25% when you eventually sell in a taxable transaction. Rental periods can also reduce your Section 121 exclusion through the non-qualified-use rules.
Sources
Educational information and estimates only. Not tax advice. Tax rules change and vary by situation; consult a qualified tax professional before acting.