40 ILCS 5/12-153
To defray the cost of the death benefit provided in Section 12-139, each employee in service shall make an additional contribution during the period prior to retirement, in the form of a deduction from salary, at a rate estimated by the board to be sufficient to provide, in any fiscal year, 1/2 of the amount necessary to meet the requirements for such benefit payments. For the fiscal year July 1, 1955 to June 30, 1956, the rate of employee contribution shall be 3/10 of 1% of salary. The employer shall make contributions for this benefit through the established tax levy in an amount equal to the contributions made by the employees.
On and after July 1, 1956, the rate of employee contribution, and the amount of employer contributions shall be fixed by the board for each fiscal year, prior to the beginning of such year, based upon the experience of the fund in the payment of benefits hereunder. Employees receiving ordinary or duty disability benefit and persons receiving a retirement annuity shall not be required to make contributions towards this benefit.
An employee in a position involving part-time employment shall make contributions in accordance with the rules of the board.
40 ILCS 5/12-153