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- Adjusted basis starts with the correct original basis
- What commonly increases adjusted basis
- What commonly decreases adjusted basis
- A simplified adjusted-basis example
- How adjusted basis affects gain or loss
- The same property can have more than one relevant basis figure
- Basis records should follow the property
- Sources
Key Facts
- Federal level: Adjusted basis is the property’s starting tax basis after all required increases and decreases.
- Federal level: Cost is the usual starting basis for purchased property, but gifts, inheritances, exchanges, and other transfers can use different federal rules.
- Federal level: Capital improvements generally increase basis, while depreciation, certain credits, reimbursements, and other recovered costs can decrease it.
- Federal level: Federal gain or loss generally compares the amount realized on a disposition with the property’s adjusted basis.
- Federal level: Depreciation can reduce basis by the amount allowed or allowable, even when the full allowable deduction was not claimed.
Adjusted basis is a running federal tax measure of investment in property. It begins with the correct original basis, then changes as events such as improvements, depreciation, casualty reimbursements, credits, or distributions affect the amount that remains invested for tax purposes.
The number matters at more than the moment of sale. It can affect gain or loss, depreciation, amortization, depletion, and other calculations tied to the unrecovered tax cost of an asset.
Adjusted basis starts with the correct original basis
Section 1012 of the Internal Revenue Code provides the general rule that the basis of purchased property is its cost. Cost can include more than the sticker price when federal capitalization rules require acquisition or production expenses to become part of the asset’s basis.
Cost is not the starting point in every case. Property received by gift or inheritance, acquired in a tax-deferred exchange, transferred between related parties, or converted from personal to income-producing use can be governed by another basis rule.
Section 1011 connects that starting number to the later adjustments required by Section 1016. The resulting figure is adjusted basis, not a new appraisal of the property’s present market value.
What commonly increases adjusted basis
Amounts properly chargeable to a capital account generally increase basis. For real property, common examples include an addition, an entire roof replacement, a new central air-conditioning system, or another improvement that adds value, prolongs useful life, or adapts the property to a different use.
Some assessments for local improvements and certain costs of defending or perfecting title can also become basis adjustments. The governing rule depends on the nature of the expenditure rather than on whether the payment felt large or unusual.
Ordinary repairs and maintenance generally do not increase basis when they merely keep property in normal operating condition. A project that is part repair and part capital improvement may require the costs to be separated under the applicable tax rules.
What commonly decreases adjusted basis
Basis falls when part of the investment has already been recovered through a deduction, credit, reimbursement, or tax-free distribution. Publication 551 lists depreciation, Section 179 deductions, certain energy and vehicle credits, casualty-loss deductions, insurance reimbursements, nontaxable corporate distributions, and some excluded canceled debt among possible decreases.
Depreciation has a particularly important rule. Basis generally decreases by depreciation allowed or allowable under the chosen method, so omitting an available depreciation deduction does not necessarily preserve a higher adjusted basis.
A casualty can produce adjustments in both directions. A deductible loss and insurance reimbursement can reduce basis, while a later restoration that qualifies as a capital improvement can increase it.
A simplified adjusted-basis example
Suppose a building begins with a $300,000 tax basis, later receives a $40,000 capital improvement, and is reduced by $20,000 of allowable depreciation. Its adjusted basis after those events is $320,000.
This simplified calculation is starting basis plus capital additions minus required reductions. It does not decide whether a particular project is an improvement, whether a different starting-basis rule applies, or how land and building costs must be allocated.
How adjusted basis affects gain or loss
Section 1001 generally measures gain as the amount realized above adjusted basis and loss as adjusted basis above the amount realized. Amount realized includes money received plus the fair market value of other property received in the disposition.
A higher adjusted basis generally produces less realized gain when the amount realized stays the same, while a lower adjusted basis generally produces more. Whether that realized amount is recognized or taxable, and how it is characterized, requires separate federal rules.
This is the bridge between basis records and a federal capital gain. For a principal residence, basis is also one part of the separate framework for capital gains on a home sale.
The same property can have more than one relevant basis figure
Federal tax rules sometimes use different basis figures for different purposes. When personal property is converted to business or rental use, for example, the depreciation basis may depend on the lower of fair market value or adjusted basis at conversion, while a later gain calculation can begin from another prescribed figure.
Gift property can also use different measures for gain and loss in certain circumstances. These exceptions are why “purchase price plus improvements” is a useful pattern but not a universal adjusted-basis formula.
Basis records should follow the property
Documents that can support adjusted basis include purchase and closing records, invoices and proof of payment for improvements, depreciation schedules, credit records, insurance settlements, casualty documentation, and prior tax returns reflecting basis adjustments. The useful record is the one that establishes the amount, date, property, and tax character of the event.
An appraisal can help establish fair market value when a federal rule calls for it, but market value does not automatically replace adjusted basis. The calculation remains a history of the applicable starting basis and every required adjustment through the relevant date.
