The time within which an appeal or a petition for review is to be perfected under Title 50A RCW is computed by excluding the day of delivery or mailing of the determination or redetermination, and by including the last day. If the last day is a Saturday or Sunday or a holiday, as defined in RCW 1.16.050, the appeal or petition for review must be perfected no later than the next business day.
Wash. Admin. Code § 192-800-065