straight-line method noun[ S ] ACCOUNTINGukus a way of depreciating(= reducing the value of) a fixed asset in a company's accounts, in which the asset's value is reduced by the same amount each year. This amount is equal to the asset's value when you can no longer use it subtracted from its value when it is new divided by the number of years you use it for: Depreciation of equipment is calculated using the straight-line method based on the estimated useful life of the equipment. Compare