Ill. Admin. Code tit. 80, § 1650.335
If an employer fails to report a member's regular service credit and earnings for a period of teaching and, at the time of the discovery of the error, more than four fiscal years have elapsed since the fiscal year in which the error occurred, the member will be required to:
(Source: Added at 29 Ill. Reg. 13244, effective August 9, 2005)