Modified Accelerated Cost Recovery System (MACRS) is a property depreciation system adopt by Internal Revenue Service (IRS). MACRS consists of two systems that determine how you depreciate your property. The main system is called the General Depreciation System (GDS) and the second system is called the Alternative Depreciation System (ADS).Generally, GDS uses the declining balance method over a shorter recovery period. ADS uses only the straight line method over a generally longer recovery period.