Wash. Admin. Code § 308-77-015
(2) When is off-highway fuel use taxable? If special fuel is used in a continuous trip, which is partly on and partly off the highway, the tax applies to all the fuel used when the total distance traveled off the highway does not exceed one mile.
A continuous trip involves the use of a highway for the transportation of persons or property from one place to another; or, in a round trip, from the origin to the destination and return to the origin.
[Statutory Authority: RCW 82.38.260. WSR 16-13-049, § 308-77-015, filed 6/9/16, effective 7/10/16; WSR 09-07-075, § 308-77-015, filed 3/16/09, effective 4/16/09; WSR 01-22-073, § 308-77-015, filed 11/1/01, effective 12/2/01.]