An accounting procedure in which an asset is expensed for depreciation purposes only when it is removed from service instead of allocating its costs across the useful life of the asset. The depreciation expense must be reduced by the asset's salvage value, if any. Public utilities and railroads are the main types of businesses that might use this type of depreciation.
The purpose of the retirement method of depreciation is to simplify accounting and recordkeeping for companies that own many similar assets that individually are low in value but together represent a significant expense. An electric company might use the retirement method of depreciation to account for the electric meters that are installed on the sides of residents' homes, for example.