(1) Any debtor who objects to all or any part of a notice of retained support may, within twenty days from the date of service of the notice, file an application for an administrative hearing. An objection under this section is the same thing as a general denial of liability to the department.

(2) The notice of retained support does not become final until there is a final administrative order.

(3) If the objection is timely, the department serves the notice of hearing on the appellant or the appellant's representative by first class mail.

(4) The department must notify the appellant that it is the appellant's responsibility to notify the department of the appellant's mailing address at the time the application is filed and also of any change of address after filing the application. Mailing by first class mail to the last address provided by the appellant constitutes service under chapters 74.20A and 34.05 RCW.