Methods for determining “substantial use” in for-hire interstate commerce
The following information provides guidance for determining if carrier equipment is used at least 25% of the time in interstate and foreign commerce.
“Substantial part” means that the motor vehicle or trailer actually crosses Washington boundaries and is used a minimum of twenty-five percent in interstate hauling for hire.
Use tax is due for those vehicles which have not been used substantially (more than 25%) in interstate commerce and on which retail sales or use tax has not been paid.