Depreciation is the systematic allocation of the depreciable amount of an asset over its useful life.There are different method of calculation of depreciation under financial accounting.The methods commonly used are: (1) Straight line method (2)written down value method. The system of claiming depreciation under income tax act is quite different from financial accounting.Depreciation provision shall apply, whether or not the assessee has claim the deduction in respect of depreciation in computing his total income.