How do I calculate the adjusted basis of my rental before I sell?

One line of arithmetic, and three inputs that people routinely get wrong

Adjusted basis is your cost plus the capital you added, less the capital you have already written off. Publication 551 frames it as making "certain adjustments to the basis of the property" before figuring gain or loss.

The three inputs that go wrong are the same every time: purchase closing costs nobody kept a settlement statement for, improvements recorded as repairs, and depreciation taken on a schedule the current owner never checked.

Fix those three and the number is reliable. Everything downstream — the tax on a sale, whether an exchange is worth the fees, how much debt you need to replace — depends on it.

Assemble it once and it serves every later question. The same figure feeds Form 4797, Schedule D and, if you exchange, Form 8824, so an hour spent on the settlement statement now saves a scramble in April.

Purchase closing costs split cleanly: buying costs go in, borrowing costs never do

Publication 551 draws the line by asking whether the cost would exist in a cash purchase: "You can't include in your basis the fees and costs for getting a loan. A fee for buying property is a cost that must be paid even if you bought the property for cash."

That single test resolves most settlement statements.

• Into basis: abstract fees, legal fees including title search and deed preparation, recording fees, surveys, transfer taxes, owner's title insurance, charges for installing utility services.
• Into basis: any amount the seller owed that you agreed to pay, such as back taxes, and unreimbursed seller real estate taxes you paid.
• Never into basis: points and loan origination fees, mortgage insurance premiums, and other charges connected with getting the loan.
• Never into basis: casualty insurance premiums, rent for occupancy before closing, and utilities relating to pre-closing occupancy.
• Not basis at all: amounts "placed in escrow for the future payment of items such as taxes and insurance."

Improvements are added; repairs were already deducted and cannot be counted twice

Basis rises by "all items properly added to a capital account", including "the cost of any improvements having a useful life of more than 1 year." A new roof, an addition, rewiring, paving and central air are the classic entries.

Publication 527 draws the boundary by purpose: an expense is an improvement if "it results in a betterment to your property, restores your property, or adapts your property to a new or different use", while an ordinary repair is deducted in the year paid.

Assessments matter too. Local improvement assessments for paving roads or building ditches increase basis, while charges for maintenance, repairs or interest relating to those improvements are deducted instead.

Depreciation comes out whether or not you ever claimed it

This is the sentence that costs people money. Publication 946 requires that you "reduce the basis of property by the depreciation allowed or allowable, whichever is greater", where allowed is what you actually deducted and allowable is what you were entitled to deduct.

So a landlord who never depreciated the building still loses the basis, and still faces the resulting gain, with no deduction to show for it. The recapture that follows is sized here and the never-claimed case is answered here.

The fix is a method change, not amended returns. Publication 946 treats using "the same impermissible method of determining depreciation in two or more consecutively filed tax returns" as an adopted method, correctable by filing Form 3115 with a section 481(a) adjustment for "any unclaimed or excess amount of allowable depreciation" — a negative adjustment taken entirely in the year of change.

If the rental used to be your home, two different basis numbers apply at once

Converting a residence creates a split that persists to the sale. Publication 551 sets the basis for depreciation at "the lesser of" the fair market value of the property on the date of the change or your adjusted basis on that date.

Its own example is worth copying: a house costing $160,000 on a $25,000 lot, plus $20,000 of improvements less a $2,000 casualty loss, has a $178,000 adjusted basis at conversion, but the depreciation basis is the $165,000 house value because "it's less than your adjusted basis."

For figuring gain on the later sale, though, "the basis for figuring a gain is your adjusted basis when you sell the property" — in that example $165,500 after $37,500 of depreciation and adding back the land. Exchanging a former home has its own rules.

A hypothetical worksheet: a $405,000 wire on a $305,000 gain

Round hypothetical numbers show why the cheque and the taxable gain are not the same thing.

• Purchase price $360,000, plus $6,000 of capitalized settlement costs, plus $64,000 of improvements: cost basis $430,000.
• Less depreciation allowed or allowable to date, $130,000: adjusted basis $300,000.
• Sale price $650,000 less $45,000 of commission and transfer taxes: amount realized $605,000.
• Realized gain $605,000 − $300,000 = $305,000, of which $130,000 is the depreciation layer.
• Mortgage payoff $200,000, so the wire is $405,000 — meaning roughly three-quarters of what you receive is taxable gain.

What the number is actually used for once you hand it over

Your adjusted basis drives three separate decisions, which is why advisors ask for it first.

It sets the tax you would pay on an outright sale, it sets whether the deferral is large enough to justify the fees, and under §1031(d) it becomes the opening figure for your basis in whatever you buy next, adjusted only for money received and gain recognized. The replacement side is worked through here.

Assemble the closing statement from the purchase, the depreciation schedules from every year, and the invoices for improvements, then let your CPA or attorney confirm the arithmetic before you set a price. Whether the resulting gain is big enough to exchange at all is answered here.