40 ILCS 5/12-141
If an employee or surviving spouse and minor children receive any compensation or payment for specific loss, disability or death under or by virtue of the Workers' Compensation Act or the Workers' Occupational Diseases Act on account of disability or death resulting from the performance of an act of duty, the benefit payable to them under this Article shall be reduced by the amount of such compensation. If the amount received as compensation exceeds such benefits, no payment shall be made to the employee or surviving spouse until the expiration of the period during which the benefit payments, accumulated at the rates herein stated, becomes equal to the sum received as compensation; provided, that the commutation of compensation to a lump sum basis as provided by the aforesaid Acts shall not increase the benefits payable by the fund but such benefits shall be adjusted to the amount of the compensation awarded under the aforesaid Acts prior to any commutation of such compensation. No interest shall be considered in these calculations.
If any employee or surviving spouse and children are denied compensation by the park or city under those Acts, or if the park or city fails to act, the denial or failure to act shall not be considered final until the claim has been adjudicated by the Illinois Workers' Compensation Commission .
40 ILCS 5/12-141