Millage rate is the rate at which property taxes are levied on property. A mill is 1/1000 of a dollar.Property taxes are computed by multiplying the taxable value of the property by the number of mills levied. The millage rate can be found on the property tax statement or by contacting the city/township/county office. mill is 1/1000 of a dollar. Property taxes are computed by multiplying the taxable value of the property by the number of mills levied. The millage rate can be found on the property tax statement or by contacting the city/township/county office.