Final answer:
In the last year of using the DDB method, the depreciation expense should be adjusted to ensure the asset's book value equals its salvage value, rather than applying the standard rate.
Step-by-step explanation:
When using the Double Declining Balance (DDB) method of depreciation, the final year of depreciation is unique because the method front-loads the depreciation expense. The goal in the last year is to ensure that the asset's book value is equal to its salvage value. Therefore, rather than applying the standard DDB depreciation rate, you must calculate the difference between the asset's current book value at the beginning of the last year and its salvage value, and this difference will be the depreciation expense for that final year. It is necessary to adjust the final year's depreciation to avoid depreciating the asset below its salvage value.