Tables A-7 and A-7a. Summary: These tables are used to determine the percentage rate used in calculating the depreciation of property. Table A-7 is for Nonresidential Real Property, using the Mid-Month Convention and Straight Line depreciation--31.5 years and lists the percentages for years 1 through 33 by month placed in service. Table A-7a is for Nonresidential Real Property, using the Mid-Month Convention and Straight Line depreciation--39 years and lists the percentages for years 1, 2-39, and 40 by month placed in service.