40 ILCS 5/8-183

(a) Each married male present employee who on June 30, 1923, was a contributor to a municipal pension fund in the city under the Public School Employees' Pension Act of 1903, and who attained age 65 subsequent to the day before the effective date and prior to July 1, 1923, shall be credited for widow's annuity as follows: 1 3/4% of his annual salary during the time between the day before the effective date and the date he attained age 65, for such service, with interest thereon at the effective rate to age 65, upon the assumption that 1/12 of such 1 3/4% of such annual salary was due on the last day of each month of such service. (b) Each male present employee, who on June 30, 1923, was a contributor to a municipal pension fund in the city under the Public School Employees' Pension Act of 1903, and who did not attain age 65 before July 1, 1923, shall be credited for widow's annuity as follows: 1 3/4% of annual salary during his service between the day before the effective date, and July 1, 1923, for such service, with interest thereon at the effective rate to July 1, 1923, upon the assumption that 1/12 of such 1 3/4% of such annual salary was due on the last day of each month of such service. (c) Each male future entrant who on June 30, 1923, was a contributor to a municipal pension fund in the city under the Public School Employees' Pension Act of 1903 shall be credited for widow's annuity with 1 3/4% of his annual salary during his service between the day before the effective date and July 1, 1923, for the term of his service, with interest thereon at the effective rate to July 1, 1923, upon the assumption that 1/12 of such 1 3/4% of such annual salary was due on the last day of each month of such service.