40 ILCS 5/11-134.3
A retired employee who (a) is receiving annuity based on a service credit of 20 or more years regardless of age at retirement or based on a service credit of 15 or more years with retirement at age 55 or over, and (b) does not qualify for the automatic increases in annuity provided for in Section 11-134.1 of this Article, and (c) elects to make a contribution to the Fund at a time and manner prescribed by the Retirement Board, of a sum equal to 1% of the amount of final monthly salary times the number of full years of service on which the annuity was based in those cases where the annuity was computed on the money purchase formula, and in those cases in which the annuity was computed under the minimum annuity formula provisions of this Article a sum equal to 1% of the average monthly salary on which the annuity was based times such number of full years of service, shall have his original fixed and payable monthly amount of annuity increased in January of the year following the year in which he attains the age of 65 years, if such age of 65 years is attained in the year 1969 or later, by an amount equal to 1 1/2%, and by an equal additional 1 1/2% in January of each year thereafter. Beginning with January of the year 1972, such increases shall be at the rate of 2% in lieu of the aforesaid specified 1 1/2%. Beginning January, 1984, such increases shall be at the rate of 3%. Beginning in January of 1999, such increases shall be at the rate of 3% of the currently payable monthly annuity, including any increases previously granted under this Article.
In those cases in which the retired employee receiving annuity has attained the age of 66 or more years in the year 1969, he shall have such annuity increased in January of the year 1970 by an amount equal to 1 1/2% multiplied by the number equal to the number of months of January elapsing from and including January of the year immediately following the year he attained the age of 65 years if retired at or prior to age 65, or from and including January of the year immediately following the year of retirement if retired at an age greater than 65 years, to and including January of the year 1970, and by an equal additional 1 1/2% in January of each year thereafter. Beginning with January of the year 1972, such increases shall be at the rate of 2% in lieu of the aforesaid specified 1 1/2%. Beginning January, 1984, such increases shall be at the rate of 3%. Beginning in January of 1999, such increases shall be at the rate of 3% of the currently payable monthly annuity, including any increases previously granted under this Article.
To defray the annual cost of such increases, the annual interest income of the Fund, accruing from investments held by the Fund, exclusive of gains or losses on sales or exchanges of assets during the year, over and above 4% a year, shall be used to the extent necessary and available to finance the cost of such increases for the following year, and such amount shall be transferred as of the end of each year, beginning with the year 1969, to a Fund account designated as the Supplementary Payment Reserve from the Investment and Interest Reserve set forth in Sec. 11-210. The sums contributed by annuitants as provided for in this Section shall also be placed in the aforesaid Supplementary Payment Reserve and shall be applied for and used for the purposes of such Fund account, together with the aforesaid interest.
In the event the monies in the Supplementary Payment Reserve in any year arising from: (1) the available interest income as defined hereinbefore and accruing in the preceding year above 4% a year and (2) the contributions by retired persons, as set forth hereinbefore, are insufficient to make the total payments to all persons estimated to be entitled to the annuity increases specified hereinbefore, then (3) any interest earnings over 4% a year beginning with the year 1969 which were not previously used to finance such increases and which were transferred to the Prior Service Annuity Reserve may be used to the extent necessary and available to provide sufficient funds to finance such increases for the current year, and such sums shall be transferred from the Prior Service Annuity Reserve.
In the event the total monies available in the Supplementary Payment Reserve from the preceding indicated sources are insufficient to make the total payments to all persons entitled to such increases for the year, a proportionate amount computed as the ratio of the monies available to the total of the total payments for that year shall be paid to each person for that year.
The Fund shall be obligated for the payment of the increases in annuity as provided for in this Section only to the extent that the assets for such purpose, as specified herein, are available.
40 ILCS 5/11-134.3