77 Ill. Adm. Code 1130.1100
Service
Section 1130.1100 Service
a) Notices
under this Subpart shall be served either personally or by certified mail upon
all parties or their agents appointed to receive service of process.
b) Service
of pleadings or motions under this Part, unless otherwise provided for in this
Subpart, shall be made by delivering in person or by depositing in the United
States Mail, properly addressed with postage prepaid, one copy to each party to
the proceeding. When any party or parties has appeared by attorney, service
upon the attorney shall be deemed service upon such party or parties.
c) Proof
of service under this Subpart shall be by certificate of attorney, affidavit or
acknowledgement.