40 ILCS 5/5-136
The annuity for the wife of an employee who attains age 57 in service, and who thereafter withdraws from or dies in service, shall be fixed, in the case of a future entrant, as of her age at the date of his withdrawal or death, whichever first occurs, and, in the case of a present employee, as of her age when the employee withdraws from or dies in service.
The widow is entitled to annuity from and after the employee's death, as follows:
If the employee withdraws from service and enters upon annuity, the annuity shall be that amount provided from his credit for widow's annuity, and widow's prior service annuity (if a present employee), at the time he withdraws from or dies in service after attainment of age 57, but shall not be less than 40% of the amount of annuity earned by the employee at the time of his withdrawal from the service after his attainment of age 57 or not less than 40% of the amount of annuity accrued to the credit of the employee on date of his death in service after his attainment of age 57 computed according to Section 5-132, subject to the limitations of Section 5-148, but shall not be less than $100 per month. If the widow is more than 5 years younger than her husband, the 40% annuity for the widow shall be reduced to the actuarial equivalent of her attained age, on the basis of the Combined Annuity Table 3% interest.
The widow of a policeman who retires from service after December 31, 1975 or who dies while in service after December 31, 1975 and on or after the date on which he becomes eligible to retire under Section 5-132 shall, if she is otherwise eligible for a widow's annuity under this Article and if the amount determined under this paragraph is more than the total combined amounts of her widow's annuity and widow's prior service annuity, or the annuities provided hereinbefore in this Section receive, in lieu of such other widow's annuity and widow's prior service annuity, or annuities provided hereinbefore in this Section a widow's annuity equal to 40% of the amount of annuity which her deceased policeman husband received as of the date of his retirement on annuity or if he dies in the service prior to retirement on annuity a widow's annuity equal to 40% of the amount of annuity her deceased policeman husband would have been entitled to receive if he had retired on the day before the date of his death in the service, except that if the age of the wife at date of retirement or the age of the widow at date of death in the service is more than 5 years younger than her policeman husband, the amount of such annuity shall be reduced by 1/2 of 1% for each such month and fraction thereof that she is more than 5 years younger at date of retirement or at date of death subject to a maximum reduction of 50%. However, no annuity under this Section shall exceed $500.00 per month.
This Section does not apply to the widow of any former policeman who was receiving an annuity from the fund on December 31, 1975 and who reenters service as a policeman, unless he renders at least 3 years of additional service after re-entry.
40 ILCS 5/5-136