Double-Declining Balance

Why use this method?
Double declining balance (DDB) is a method of accelerated depreciation (the process of deducting the purchase price of a fixed asset over several accounting periods). Like sum of the years' digits, it's a good method to use when the productivity of an asset is expected to be greater during its early years of use.

DDB is a more accelerated method than sum of the years' digits. It yields a higher depreciation expense early on, and declines more dramatically. The one you choose will depend upon the most logical way to allocate costs for a particular asset.

It can be advantageous to begin depreciating under DDB and switch to the straight-line method some years into the asset's useful life. Your accountant can help you understand whether this method is right for you.

How does it work? 

Depreciation expense = 2 X 1 estimated useful life X book value at the beginning of the year