C.R.S. § 26-13.5-116

(1) If a party retains legal counsel to represent him or her in an APA case, a written notice of representation signed by both the party and his or her attorney must be received by the delegate child support enforcement unit. The notice of representation is not effective until delivered to the delegate child support enforcement unit. (2) If a party terminates legal representation, the party shall deliver written notice of such termination to the delegate child support enforcement unit. The termination is effective upon receipt of delivery. (3) Except for service of the notice upon the APA-respondent, an attorney of record must, on behalf of his or her client, receive a copy of all documents delivered to the parties in an APA case.