820 ILCS 80/65

Employee contributions deducted by the participating employer through payroll deduction shall be paid by the participating employer to the Fund using one or more payroll deposit retirement savings arrangements established by the Board under subsection (h) of Section 30 of this Act, either: (1) on or before the last day of the month following the month in which the compensation otherwise would have been payable to the employee in cash; or (2) by a deadline prescribed by the Board for making such payments, but not later than the due date for the deposit of tax required to be deducted and withheld relating to collection of income tax at source on wages or for the deposit of tax required to be paid under the unemployment insurance system for the payroll period to which such payments relate.