RCW 42.52.110: Compensation for official duties or nonperformance.

No state officer or state employee may, directly or indirectly, ask for or give or receive or agree to receive any compensation, gift, reward, or gratuity from a source for performing or omitting or deferring the performance of any official duty, unless otherwise authorized by law except: (1) The state of Washington; or (2) in the case of officers or employees of institutions of higher education, a governmental entity, an agency or instrumentality of a governmental entity, or a nonprofit corporation organized for the benefit and support of the state employee's agency or other state agencies pursuant to an agreement with the state employee's agency.