MACRS  The Modified Accelerated Cost Recovery System (MACRS) is the current tax depreciation system in the United States. Under this system, the capitalized cost (basis) of tangible property is recovered over a specified life by annual deductions for depreciation. The lives are specified broadly in the Internal Revenue Code. The Internal Revenue Service (IRS) publishes detailed tables of lives by classes of assets. The deduction for depreciation is computed under one of two methods (declining balance switching to straight line or straight line) at the election of the taxpayer, with limitations. See IRS Publication 946 for a 120-page guide to MACRS. Tax deductions for depreciation have been allowed in the U.S. since the inception of the income tax. Prior to 1971, these deductions could be computed in a variety of manners over a wide range of lives, under old Bulletin F. In 1971, Congress introduced the Class Life Asset Depreciation Range (ADR) system in an attempt to simplify calculations and provide some uniformity. Under ADR, the IRS prescribed lives for classes of assets based on the nature or use of the asset. Such classes included general classes (such as office equipment) and industry classes (such as assets used in the manufacture of rubber goods). Taxpayers could use their choice of several methods of depreciating assets, including straight line, declining balance, and sum of years digits. Asset costs and accumulated depreciation were tracked by "vintage accounts" consisting of all assets within a class acquired in a particular tax year. All vintage accounts for the same year were assumed placed in service in the middle of the year; however, a taxpayer could elect the modified half year convention with potentially favorable results. In 1981, Congress again changed the depreciation system, providing generally for shorter lives for recovery of costs. Under the Accelerated Cost Recovery System (ACRS), broad groups of assets were assigned based on the old ADR lives (which the IRS has updated since). Taxpayers were permitted to calculate depreciation only under the declining balance method switching to straight line or the straight line method. Other changes applied as well. The present MACRS system was adopted as part of the Tax Reform Act of 1986. California is the only state which does not fully conform its depreciation schedule to MACRS. Under MACRS a taxpayer must compute tax deductions for depreciation of tangible property using specified lives and methods. Assets are divided into classes by type of asset or by business in which the asset is used. (See tables of classes below.) Where a general class based on the nature of the asset applies (00.xx classes below), that class takes precedence over the use class.