Every interstate motor fuel user subject to the tax imposed by this act shall be entitled to a credit on such tax equivalent to the statutory gallon rate at the time purchased on all motor fuel purchased within this state by such interstate motor fuel user for operations within and without this state and upon which the tax imposed by this state has been paid by such interstate motor fuel user. Such evidence of the payment of such tax as may be required by or is satisfactory to the director shall be furnished by any interstate motor fuel user claiming the credit authorized by this section. When the amount of the credit under this section to which any interstate motor fuel user is entitled for any reporting period exceeds the amount of the tax for which such interstate motor fuel user is liable for the same period, such excess, under rules and regulations adopted by the secretary of revenue, shall be allowed as a credit on the tax for which such interstate motor fuel user would be otherwise liable for the current quarter or any of the seven consecutive succeeding quarters, or for the current year if the interstate motor fuel user is reporting annually. When the amount of credit under this section exceeds $10, the interstate motor fuel user may elect to have refunded to it the amount of such credit. The secretary of revenue shall adopt rules and regulations governing the application for credits and refunds under this section. Refunds shall be paid to the interstate motor fuel user entitled thereto from the motor vehicle fuel tax refund fund.