(1) If the department finds that any member, beneficiary, or other person or entity has been paid an amount of retirement benefits to which that person or entity is not entitled, and the person is not entitled to a continuing benefit from any of the retirement systems listed in RCW 41.50.030, the department may issue an order and notice of assessment specifying the amount due, including interest, to be remitted to the department. The order and notice of assessment shall be served upon any person or entity who may have received benefits to which the person or entity is not entitled. The order and notice of assessment shall be served by the department in the manner prescribed for the service of a summons in a civil action, or by certified mail to the last known address of the obligor as shown by the records of the department.

(2) Any notice of assessment under subsection (1) of this section shall constitute a determination of liability from which the member, beneficiary, or other person or entity served may appeal by filing a petition for adjudicative proceedings with the director personally or by mail within sixty days from the date the assessment was served. If a petition for adjudicative proceedings is not filed within sixty days of the delivery of the notice of assessment, the determination that was the basis for establishing the overpayment debt and the assessment is conclusive and final.

(3) This section creates an administrative process for the collection of overpayments from persons who are not entitled to a continuing benefit from one of the retirement systems listed in RCW 41.50.030. The collection of overpayments from persons entitled to a continuing benefit from one of the retirement systems listed in RCW 41.50.030 is governed by RCW 41.50.130.