40 ILCS 5/8-234: Basis of salary deduction.

The total of salary deductions for employee contributions for annuity purposes to be considered for any 1 calendar year shall not exceed that produced by the application of the proper salary deduction rates to the highest annual salary considered for annuity purposes for such year.

For the year 1957 or prior years, where deductions from salary on overtime pay may have, in the case of some daily or hourly paid employees, resulted in excess deductions for the year, such excess deductions may be considered as proper salary deductions for age and service and widow's annuity, unless refunded at the employee's request.