The tax basis of an asset is generally its cost. Determining such cost may require allocations where multiple assets are acquired together. Tax basis may be reduced by allowances for depreciation. Such reduced basis is referred to as the adjusted tax basis. Adjusted tax basis is used in determining gain or loss from disposition of the asset. Tax basis may be relevant in other tax computations.

Tax basis of a member's interest in a partnership and other flow-through entity is generally increased by the members share of income and reduced by the share of loss. The tax basis of property acquired by gift is generally the basis of the person making the gift. Tax basis in property received from corporations or partnerships may be the corporation's or partnership's basis in some cases.

Determining cost basis

The basis of property is generally the property's cost. Cost is the amount paid for the property in cash or other property.

Where an asset is acquired in a purchase of just the asset, tax basis includes cash paid plus liabilities assumed. For example, if Joe acquires a building for $10,000 cash and assumes a mortgage for $80,000, Joe's basis in the building is $90,000. If multiple items of property are acquired together in a single transaction, the tax basis must generally be allocated to the items in proportion to their values at the time of acquisition.

Fungible property (e.g., bushels of wheat or shares of corporation stock) may include items of property acquired at different times with differing bases. If such property is sold, the taxpayer may need to use an assumption (such as average cost

Average cost

In economics, average cost or unit cost is equal to total cost divided by the number of goods produced . It is also equal to the sum of average variable costs plus average fixed costs...

 or FIFO

FIFO

FIFO is an acronym for First In, First Out, an abstraction related to ways of organizing and manipulation of data relative to time and prioritization...

) for determining the cost of the portion of the property sold.

Adjustments to basis

The tax basis of an asset subject to cost recovery must be reduced by deductions allowed for such cost recovery. For example, if Joe claimed $25,000 of depreciation deductions on his building, his adjusted basis would be the $90,000 as above less $25,000, or $65,000. Cost recovery deductions may include depreciation, amortization, and deducted losses or declines in value. Some jurisdictions (e.g., Germany) allow a deduction for decline in value of certain assets, which reduces tax basis.

Partner's basis in partnership

A partner's tax basis in the partnership generally equals the adjusted basis of property contributed or cash paid plus any income recognized by the partner on the formation of the partnership. Such income may arise from services performed in exchange for the partnership interest. The member's basis is adjusted each year for his share of the entity's income or loss. Generally, the adjustment cannot reduce tax basis below zero. Similar rules apply for other flow-through entities, such as S corporation

S Corporation

An S corporation, for United States federal income tax purposes, is a corporation that makes a valid election to be taxed under Subchapter S of Chapter 1 of the Internal Revenue Code....

s and flow-through Limited liability companies. The member's basis is also reduced for distributions, and increased by income recognized upon distributions. Rules vary by country.

Under United States rules, a partner's tax basis is also increased to the extent the partner is considered to have assumed liabilities. The partner's tax basis is decreased to the extent the partner is considered to have been relieved of liabilities. For example, if Ann is a general partner of ABC partnership, Ann's tax basis in the partnership is increased if the partnership borrows money. Special rules apply with regard to nonrecourse debt

Nonrecourse debt

Non-recourse debt or a non-recourse loan is a secured loan that is secured by a pledge of collateral, typically real property, but for which the borrower is not personally liable. If the borrower defaults, the lender/issuer can seize the collateral, but the lender's recovery is limited to the...

.

Basis of gifts and inheritances

Tax basis of property received by a U.S. person by gift is the donor's tax basis of the property. If the fair market value of the property exceeded this tax basis and the donor paid gift tax, the tax basis is increased by the gift tax. This adjustment applies only if the recipient sells the property at a gain.

Tax basis of property acquired by inheritance (i.e., from a decedent) before 2010 is the fair market value at the date of death. However, certain alternative basis may be used at the election of the estate of the decedent. Property so acquired after 2009 is treated as if acquired by gift, but the basis is limited to fair market value.

Carryover and substituted basis

Property acquired in a non-taxable exchange takes the basis of the property exchanged. Examples of non-taxable exchanges include like kind exchanges, partnership liquidations, and corporate reorganizations.

Property acquired by distribution from a corporation or partnership may retain the same tax basis to the member as the entity's tax basis in certain circumstances. This basis is increased by any gain the member must recognize on the distribution.

Other issues

Tax basis may be further adjusted for certain computations relating to controlled foreign corporations

Controlled Foreign Corporation

Controlled foreign corporation rules are features of an income tax system designed to limit artificial deferral of tax by using offshore low taxed entities. The rules are needed only with respect to income of entities that is not currently taxed to the owners of the entity. The basic mechanism and...

in the U.S.