The tax levied by RCW 82.08.020 shall not apply to sales to nonresidents of this state for use outside of this state of:
when such machinery, implements, and parts will be transported immediately outside the state. As proof of exemption, an affidavit or certification in such form as the department of revenue shall require shall be retained as a business record of the seller.
RCW 82.08.0268
Intent-1980 c 37: See note following RCW 82.04.4281.