Accelerated Cost Recovery System

The rules for calculating depreciation (annual write-offs) for buildings, furniture, and other assets were called the Accelerated Cost Recovery System (ACRS). The depreciation system after 1986 is called the Modified Accelerated Cost Recovery System (MACRS). Depreciation write-offs are technically called recovery deductions under these rules. The basic approach to calculating depreciation under these rules is to multiply a percentage provided in charts by the IRS by the costs (adjusted basis) of the building, furniture, or other assets you are depreciating. The depreciation period for certain commercial real estate, for example, is 39 years.