Understanding Adjusted Basis in Real Estate Investments
Adjusted basis is the running tally of what a property is really worth for tax purposes — and it determines how much gain or loss you actually owe when you sell.
- Adjusted basis starts with purchase price, then rises with improvements and falls with depreciation.
- It is the number subtracted from your sale price to calculate taxable gain.
- Getting it wrong can mean overpaying taxes or triggering an IRS audit.
- Every capital improvement and every depreciation deduction you take shifts the number.
Adjusted basis is the tax code's version of 'what you have into' a property. It starts with your original cost basis — typically the purchase price plus closing costs — and is then modified upward by capital improvements you make and downward by depreciation deductions you claim over time. When you eventually sell, the IRS subtracts your adjusted basis from the sale price to determine your taxable gain. The lower your adjusted basis, the larger the gain the government sees, and the more tax you owe.
How Original Basis Is Established
Your starting point is the purchase price of the property. But basis is not just the number on the contract. It also includes most costs you paid to acquire the property: title insurance, legal fees, recording fees, transfer taxes, and certain loan origination points. If you inherited the property, your basis is generally the fair market value at the date of the original owner's death — a valuable reset known as a stepped-up basis. If you received the property as a gift, you typically carry over the donor's basis instead.
What Increases and Decreases Adjusted Basis
Once you own the property, two forces pull the basis in opposite directions. Capital improvements push it up. A capital improvement is anything that adds value, prolongs the property's useful life, or adapts it to a new use — a new roof, an HVAC system, an addition, or a parking lot repaving. Routine repairs and maintenance do not count; they are deducted as operating expenses in the year incurred, not added to basis.
Depreciation pulls basis down. Each year you own income-producing real estate, the IRS lets you deduct a portion of the building's value as depreciation — 27.5 years for residential rentals, 39 years for commercial property. Whether you actually claim those deductions or not, the IRS reduces your basis by the amount you were allowed to claim. This is the mechanism that makes depreciation recapture so significant at sale: years of deductions have quietly eroded your basis, enlarging the eventual taxable gain.
- The IRS reduces your basis by depreciation 'allowed or allowable' — meaning even if you forgot to claim depreciation in a prior year, your basis is still reduced as if you had. You can file Form 3115 to catch up on missed deductions, but you cannot simply ignore past depreciation and keep a higher basis.
Calculating Gain at Sale Using Adjusted Basis
When you sell, the formula is straightforward: Amount Realized (sale price minus selling costs) minus Adjusted Basis equals Realized Gain. If your adjusted basis is $300,000 and you sell for $600,000 net of commissions and fees, your realized gain is $300,000. That gain is then sorted into categories — long-term capital gain taxed at preferential rates, and depreciation recapture taxed as ordinary income up to 25% for real property. The adjusted basis figure is the hinge on which all of this turns.
| Event | Effect on Basis | Example |
|---|---|---|
| Purchase price + closing costs | Sets original basis | $500,000 |
| Capital improvement (new roof) | Increases basis | + $40,000 |
| Annual depreciation claimed | Decreases basis | - $12,820 per year |
| Casualty loss deduction taken | Decreases basis | - $15,000 |
| Insurance reimbursement received | Decreases basis | - $10,000 |
Tracking adjusted basis matters most at the moment of sale, but it also affects you if you do a 1031 exchange, convert the property to personal use, or donate it to charity. In a 1031 exchange, for instance, your adjusted basis in the relinquished property carries over (with modifications) into the replacement property, deferring — but not eliminating — the embedded gain.
Sources
- IRS Publication 551 (Basis of Assets) covers original basis, adjustments, and inherited property rules.
- IRS Publication 946 (How to Depreciate Property) details MACRS depreciation periods for real estate.
- IRC Section 1016 governs required adjustments to basis including depreciation allowed or allowable.
- IRS Revenue Procedure 2015-13 and Form 3115 govern accounting method changes for missed depreciation.
