Ill. Admin. Code tit. 50, § 2907.30
a) Scope of Procedure
Each insurer licensed to write workers' compensation coverage in the State shall report to the Department information on an aggregate basis before March 1 of each year, relating to claims in the State opened within the prior calendar year.
(Source: Amended at 43 Ill. Reg. 3285, effective February 25, 2019)