The double-declining balance method multiplies twice the straight-line method percentage by the beginning book value each period. Because the book value decreases each period, the depreciation expense decreases as well. In the final period, the depreciation expense is simply the difference between the salvage value and the book value. The double-declining balance method accelerates the depreciation taken at the beginning of an asset's useful life. Because of this, it more accurately reflects the true value of an asset that loses value quickly. When you drive a brand new vehicle off the lot at the dealership, its value decreases considerably in the first few years. Toward the end of its useful life, the vehicle loses a smaller percentage of its value every year.