Wash. Rev. Code § 41.32.263
A member of the retirement system who is a member of the state legislature or a state official eligible for the combined pension and annuity provided by RCW 41.32.497, or 41.32.498, as now or hereafter amended shall have deductions taken from his or her salary in the amount of seven and one-half percent of earnable compensation and that service credit shall be established with the retirement system while such deductions are reported to the retirement system, unless he or she has by reason of his or her employment become a contributing member of another public retirement system in the state of Washington. Such elected official who has retired or otherwise terminated his or her public school service may then elect to terminate his or her membership in the retirement system and receive retirement benefits while continuing to serve as an elected official. A member of the retirement system who had previous service as an elected or appointed official, for which he or she did not contribute to the retirement system, may receive credit for such legislative service unless he or she has received credit for that service in another state retirement system, upon making contributions in such amounts as shall be determined by the board of trustees.
RCW 41.32.263
Intent-1991 c 35: See note following RCW 41.26.005.