40 ILCS 5/21-105.2

Beginning July 1, 1991, the State and all political subdivisions that have any employees who are subject to mandatory Social Security coverage shall report the wages of those employees on their quarterly wage reports to the IRS, and shall make the appropriate FICA contributions as required by law with respect to those employees. Such employees may be added to the appropriate coverage groups in accordance with the modification procedures provided in this Article.