(40 ILCS 5/6-128) (from Ch. 108 1/2, par. 6-128)
    Sec. 6-128. (a) A future entrant who withdraws on or after July 21, 1959, after completing at least 23 years of service, and for whom the annuity otherwise provided in this Article is less than that stated in this Section, has a right to receive annuity as follows:
    If he is age 53 or more on withdrawal, his annuity after withdrawal, shall be equal to 50% of his average salary.
    An employee who reaches compulsory retirement age and who has less than 23 years of service shall be entitled to a minimum annuity equal to an amount determined by the product of (1) his years of service and (2) 2% of his average salary.
    An employee who remains in service after qualifying for annuity under this Section shall have added to this annuity an additional 1% of average salary for each completed year of service or fraction thereof rendered until July 21, 1959, and an additional 1% for a total of 2% of average salary from July 21, 1959. Each future entrant who has completed 23 years of service before reaching age 53 shall have added to this annuity 1% of average salary for each completed year of service or fraction thereof in excess of 23 years up to age 53.
    (b) In lieu of the annuity provided in the foregoing provisions of this Section any future entrant who withdraws from the service either (i) after December 31, 1983 with at least 22 years of service credit and having attained age 52 in the service, or (ii) after December 31, 1984 with at least 21 years of service credit and having attained age 51 in the service, or (iii) after December 31, 1985 with at least 20 years of service credit and having attained age 50 in the service, or (iv) after December 31, 1990 with at least 20 years of service regardless of age, may elect to receive an annuity, to begin not earlier than upon attainment of age 50 if under that age at withdrawal, computed as follows: an annuity equal to 50% of average salary, plus additional annuity equal to 2% of average salary for each completed year of service or fraction thereof rendered after his completion of the minimum number of years of service required for him to be eligible under this subsection (b). However, the annuity provided under this subsection (b) may not exceed 75% of average salary.
    (c) In lieu of the annuity provided in any other provision of this Section, a future entrant who withdraws from service after the effective date of this amendatory Act of the 93rd General Assembly with at least 20 years of service may elect to receive an annuity, to begin no earlier than upon attainment of age 50 if under that age at withdrawal, equal to 50% of average salary plus 2.5% of average salary for each completed year of service or fraction thereof over 20, but not to exceed 75% of average salary.
    (d) For the purpose of this Section, "average salary" means the average of the highest 4 consecutive years of salary within the last 10 years of service.
(Source: P.A. 93-654, eff. 1-16-04.)