In the United States, there are depreciation ranges for different assets. Normally,
fixed assets are written off for tax purposes using the ‘modified accelerated cost
recovery system’. The most common form of this involves three-, five- or seven-year
classes. These are depreciated by the declining balance method, using twice the
straight-line rate. Commercial buildings have a 39-year life on a straight-line
basis since 1993 changes in tax law.