Any person, firm, corporation, association, political subdivision, or department employing a person owing a debt for overpayment of public assistance received as defined in RCW 74.04.300, shall honor, according to its terms, a duly executed assignment of earnings presented to the employer by the secretary as a plan to satisfy or retire an overpayment debt. This requirement to honor the assignment of earnings is applicable whether the earnings are to be paid presently or in the future and continues in force and effect until released in writing by the secretary. Payment of moneys pursuant to an assignment of earnings presented to the employer by the secretary serves as full acquittance under any contract of employment, and the state warrants and represents it shall defend and hold harmless such action taken pursuant to the assignment of earnings. The secretary is released from liability for improper receipt of moneys under assignment of earnings upon return of any moneys so received.