40 ILCS 5/6-167
Beginning on the effective date and prior to September 1, 1957, 1% of each payment of salary of not more than $3,000 of each employee and beginning September 1, 1957, 1% of each payment of salary of not more than $6,000 of each present employee and future entrant shall be deducted and contributed to the fund for widow's annuity. After September 1, 1967 and prior to January 1, 1976, 1%, and beginning January 1, 1976, 1 1/2% of salary without limitation shall be deducted from the pay of each present employee and future entrant and contributed to the fund for widow's annuity or Tier 2 surviving spouse's annuity. The deduction shall be made at the time the payments of salary are payable and shall continue during the service of the employee.
Concurrently with each contribution, the city shall contribute 2% of each payment of salary.
Each contribution by the employee and the city shall be allocated to the accounts of and credited to the employee for widow's annuity or Tier 2 surviving spouse's annuity.
40 ILCS 5/6-167