Washington Revised Code Title 82. Excise Taxes § 82.32.026. Registration--Seller's agent--Streamlined sales and use tax agreement

(1) A seller, by written agreement, may appoint a person to represent the seller as its agent. The seller's agent has authority to register the seller with the department under RCW 82.32.030. An agent may also be a certified service provider, with authority to perform all the seller's sales and use tax functions, except that the seller remains responsible for remitting the tax on its own purchases.

(2) The seller or its agent must provide the department with a copy of the written agreement upon request.