The amount per $1,000 that is used to calculate taxes on property. Millage rates are most often found in personal property taxes, where the expressed millage rate is multiplied by the total taxable value of the property to arrive at the property taxes due. Millage rates are also used by school boards to calculate local school taxes to be collected, based on a derivation of the total property value within school district boundaries.

The term is derived from the root word mill, which means "thousand". Millage rates are often expressed mathematically with the symbol %o, as in 1%o, which is one part per thousand, or 0.1%. Millage rates for individual properties are usually found on the property deed itself.