Wash. Rev. Code § 43.05.140
The department of revenue, the department of labor and industries in respect to its duties in Title 51 RCW, and the employment security department shall develop and administer a pilot voluntary audit program. Voluntary audits can be requested by businesses from any of these agencies according to guidelines established by each agency. No penalty assessments may be made against participants in such a program except when the agency determines that either a good faith effort has not been made by the taxpayer or premium payer to comply with the law or that the taxpayer has failed to remit previously collected sales taxes to the state. The persons conducting the voluntary audit shall provide the business undergoing the voluntary audit an audit report that describes errors or omissions found and future reporting instructions. This program does not relieve a business from past or future tax or premium obligations.
RCW 43.05.140