"Sec. 7   RCW 82.21.050 and 1989 c 2 s 12 are each amended to read as follows:
     (1) Credit ((shall be)) is allowed in accordance with rules of the department of revenue for taxes paid under this chapter with respect to fuel carried from this state in the fuel tank of any airplane, ship, truck, or other vehicle.
     (2) Credit ((shall be)) is allowed, in accordance with rules of the department, against the taxes imposed in this chapter for any hazardous substance tax paid to another state with respect to the same hazardous substance. The amount of the credit ((shall)) may not exceed the tax liability arising under this chapter with respect to that hazardous substance. For the purpose of this subsection:
     (a) "Hazardous substance tax" means a tax:
     (i) Which is imposed on the act or privilege of possessing hazardous substances, and which is not generally imposed on other activities or privileges; and
     (ii) Which is measured by the value of the hazardous substance, in terms of wholesale value or other terms, and in the determination of which the deductions allowed would not constitute the tax an income tax or value added tax.
     (b) "State" means (i) the state of Washington, (ii) a state of the United States other than Washington, or any political subdivision of such other state, (iii) the District of Columbia, and (iv) any foreign country or political subdivision thereof.
     (3) Credit is allowed, in accordance with rules adopted by the department, in an amount equal to the taxes owed under RCW 82.21.030(1)(b) on the possession of propane."