Sum-of-the-Years'-Digits Convention

The sum-of-the-years’-digits depreciation method applies a midmonth convention, giving a full month’s depreciation in the acquisition month if the asset is purchased on or before the 15th of the month. No depreciation is allowed if the asset is acquired after the 15th. In the disposal month, no depreciation is allowed if the asset is disposed of before the 16th; a full month’s depreciation is allowed if the asset is disposed of after the 15th.