The method that allocates an equal amount of depreciation to each year of an asset's service life is:

Answer: Straight line method of depreciation

Explanation: Under the straight line method of depreciation the asset is expensed over its useful life. In this method, depreciation or amortization is calculated by dividing the difference of initial cost and salvage value of the asset from its useful number of years.

This method is not commonly used for assets having longer term period but still some business entities use it as it is easy to calculate.