Accelerated depreciation refers to any one of several methods by which a company, for 'financial accounting' or tax purposes, depreciates a fixed asset in such a way that the amount of depreciation taken each year is higher during the earlier years of an asset's life. For financial accounting purposes, accelerated depreciation is expected to be much more productive during its early years, so that depreciation expense will more accurately represent how much of an asset's usefulness is being used up each year. For tax purposes, accelerated depreciation provides a way of deferring corporate income taxes by reducing taxable income in current years, in exchange for increased taxable income in future years. This is a valuable tax incentive that encourages businesses to purchase new assets.

For financial reporting purposes, the two most popular methods of accelerated depreciation are the double declining balance method and the sum-of-the-years’ digits method. For tax purposes, the allowable methods of accelerated depreciation depend on the tax law that the taxpayer is subject to. In the United States, the two currently allowable depreciation methods for tax purposes are both accelerated depreciation methods (ACRS and MACRS).