Section 40 ILCS 5/5-127 - Minimum amount of annuity of present employeeAny present employee who withdraws on or after the effective date having at least 20 years of service and for whom the annuity otherwise provided in this Article is less than the amount stated in this section, has a right to annuity as follows:
(1) If he is at least age 50 on withdrawal, his annuity, from and after such withdrawal, shall be 50% of the compensation attached to or appropriated for the rank in the police department which he may have held by civil service appointment on the day one year prior to the date of withdrawal from service. Beginning July 1, 1931, the compensation to be used shall be not less than that in effect on July 1, 1931;(2) If he is less than age 50 on withdrawal, his annuity, beginning on the date he becomes age 50, shall be 50% of his salary at withdrawal but not in excess of $900 a year.