A measurement of currency used primarily in accounting, planning, billing and tax assessment that represents one tenth of a cent, or one thousandth of a dollar (a "millidollar").

A mill rate is a billing rate for a commodity charged by the tenth of a cent. Property tax mill rates, for example, are charged as tenths of a penny in taxes per dollar of property value; energy service mill rates are typically charged as tenths of a cent per kilowatt-hour of consumed energy.