2005 Washington Revised Code RCW 82.38.060: Tax computation on mileage basis.

In the event the tax on special fuel imported into this state in the fuel supply tanks of motor vehicles for taxable use on Washington highways can be more accurately determined on a mileage basis the department is authorized to approve and adopt such basis. When a special fuel user imports special fuel into or exports special fuel from the state of Washington in the fuel supply tanks of motor vehicles, the amount of special fuel consumed in such vehicles on Washington highways shall be deemed to be such proportion of the total amount of such special fuel consumed in his entire operations within and without this state as the total number of miles traveled on the public highways within this state bears to the total number of miles traveled within and without the state. The department may also adopt such mileage basis for determining the taxable use of special fuel used in motor vehicles which travel regularly over prescribed courses on and off the highways within the state of Washington. In the absence of records showing the number of miles actually operated per gallon of special fuel consumed, fuel consumption shall be calculated at the rate of one gallon for every: (1) Four miles traveled by vehicles over forty thousand pounds gross vehicle weight; (2) seven miles traveled by vehicles twelve thousand one to forty thousand pounds gross vehicle weight; (3) ten miles traveled by vehicles six thousand one to twelve thousand pounds gross vehicle weight; and (4) sixteen miles traveled by vehicles six thousand pounds or less gross vehicle weight.

[1996 c 90 § 1; 1989 c 142 § 1; 1971 ex.s. c 175 § 7.]