A number of depreciation keys that are supplied in the standard chart of depreciation for the United States are described here.

For MACRS, the following depreciation keys are defined in accordance with the Internal Revenue Service depreciation rate tables:

• M200 3, 5, 7, 10 years property
• M150 15, 20 years property
• MSTL 27.5 and 31.5 years property

For ACRS, the following depreciation keys are defined in accordance with the Internal Revenue Service depreciation rate tables:

• A0xx defines the ACRS depreciation percentages for 3.5 and 10 years property.
• A15x defines the ACRS depreciation percentages for 15 years property. Depending on the month placed in service, use A15A (Jan.) through A15L (Dec.).
• A18x defines the ACRS depreciation percentages for 18 years property. Use A18A (Jan.) through A18L (Dec.) for assets placed in service before June 23rd 1984. Use A18M (Jan.) through A18X (Dec.) for assets placed in service after June 22nd 1984.
• A19x defines the ACRS-depreciation percentages for 19 years property. Depending on the month placed in service, use A19A (Jan.) through A19L (Dec.).