§ RCW 29A.04.031Date of mailing.

For registered voters voting by mail, "date of mailing" means the date of the postal cancellation on the envelope in which the ballot is returned to the election official by whom it was issued. For all service and overseas voters, "date of mailing" means the date stated by the voter on the declaration.
Notes:
Notice to registered poll voters—Elections by mail—2011 c 10: See note following RCW 29A.04.008.
Legislative intent—Effective date—1987 c 346: See notes following RCW 29A.40.010.