When depreciation occurs faster than expected the US tax allows for it. Assets are divided into classes and the method of depreciation is listed. It is meant to encourage investment. Another term for this is modified accelerated cost recovery system (MACRS).
This method of depreciaition helps companies to recover costs faster than through traditional straight line depreciation. Advantages of accelerated depcreiation including quicker recovery of cost and lower taxes.
Computing depreciation rates faster than the straight line option. The two methods are declining balance or taking the sum of the years digits as the depreciation rate. This results in a larger write off than the value. It suggests that the value is more because the longer the asset it owned it becomes less valuable. The total depreciation charge stays the same.