Wash. Rev. Code § 15.65.410
The director shall prescribe in each marketing order and agreement the time, place, and method for payment and collection of assessments under such order or agreement upon any uniform basis applicable alike to all producers subject to such assessment, and upon the same or any other uniform basis applicable alike to all handlers subject to such assessment. For such purpose the director may, by the terms of the marketing order or agreement:
Unless the director has otherwise provided in any marketing order or agreement, assessments payable by producers shall be paid prior to the time when the affected unit is shipped off the farm, and assessments payable to handlers shall be paid prior to the time when the affected units are received by or for the account of the first handler. No affected units shall be transported, carried, shipped, sold, marketed, or otherwise handled or disposed of until every due and payable assessment herein provided for has been paid by the producer or first handler and the receipt issued.
RCW 15.65.410