A contra asset is an account that carries a natural credit balance even though most assets have a normal debit balance. Assets represent items a company owns and uses during business operations, such as cash, inventory, and prepaid expenses along with buildings, vehicles, and land. In the accounting equation — assets equal liabilities plus owners' equity — the preceding items are all debits that increase the asset side of the equation. The contra asset still resides on the asset side of the equation, just with a credit balance. The purpose of a contra account is to reduce an asset account, such as accumulated depreciation, reducing a building asset account.
In financial accounting, a contra asset account always relates to an asset account. Two of the most common examples of a contra account are the allowance for doubtful accounts and accumulated depreciation. In most cases, these accounts will not show up on a standard balance sheet, which is the financial statement that contains all asset accounts. The contra account nets together with the sum of the related account in order to reduce its balance. The net difference between the asset account and the contra account is the total shown on the balance sheet for a given period.
Companies may use a financial statement disclosure to identify and describe the use of a contra asset account. For example, the allowance for doubtful accounts indicates money owed from customers a company does not expect to receive. There can be multiple reasons why the company does not expect to receive this owed money. Most financial disclosures dictate the amount expected to be lost, how the company came up with the figure, and any financial impact this lost capital will have on the business. A separate disclosure paragraph is often necessary for each contra account.
Contra accounts may have a zero balance in some cases, though the actual instances of this may be rare. The allowance for doubtful accounts, for example, is zero if the company collects all of its open customer receivables or the allowance amounts were written off as a bad debt expense. Accumulated depreciation contra accounts have a balance so long as the company owns the related asset. When a company sells the asset — usually a long-term asset such as a building or vehicle — the closing entry removes the related accumulated depreciation in the contra asset account. Therefore, these accounts will have no balance to net against an asset account or report through disclosures.