305 ILCS 5/10-28
The Illinois Department may provide notice at any time to the parties to a judicial action filed under this Code, or under any other law providing for support of a spouse or dependent child, that child support enforcement services are being provided by the Illinois Department under this Article X. The notice shall be sent by regular mail to the party's last known address on file with the clerk of the court or the State Case Registry established under Section 10-27. After notice is provided pursuant to this Section, the Illinois Department shall be entitled, as if it were a party, to notice of any further proceedings brought in the case. The Illinois Department shall provide the clerk of the court with copies of the notices sent to the parties. The clerk shall file the copies in the court file.
305 ILCS 5/10-28