WAC 434-230-130
WAC 434-230-130. Envelopes
Mail-in ballots must be accompanied by the following:
(1) A security envelope or sleeve, which may not identify the voter and must have a hole punched in a manner that will reveal whether a ballot is inside;
(2) A return envelope, which must be addressed to the county auditor and have a hole punched in a manner that will reveal whether the security envelope is inside. The return envelope must display the official election materials notice required by the United States Postal Service and conform to regulations required by the county auditor's U.S. Postal Service business reply mail account.