# Depreciation conventions (tax) IRS Publication 946 (2025). wanderbooks depreciates on the book basis (straight line, prorated by days for partial months); tax depreciation stays with the CPA. These are the tax conventions the book method is distinct from. ## IRS Publication 946 Source: Retrieved: 2026-10-13 SHA-256 of the retrieved file (`p946.txt`): `b86506e17ebbb3ab4a920ad9ded15da9327e85a61ebede243031d152a5283134` **Conventions** > Under MACRS, averaging conventions establish when the recovery period begins and ends. The convention you use determines the number of months for which you can claim depreciation in the year you place property in service and in the year you dispose of the property. **Mid-month** > Under this convention, you treat all property placed in service or disposed of during a month as placed in service or disposed of at the midpoint of the month. This means that a one-half month of depreciation is allowed for the month the property is placed in service or disposed of. **Straight line rate** > You determine the straight line depreciation rate for any tax year by dividing the number 1 by the years remaining in the recovery period at the beginning of that year. When figuring the number of years remaining, you must take into account the convention used in the year you placed the property in service. If the number of years remaining is less than 1, the depreciation rate for that tax year is 1.0 (100%).