(a) In lieu of retirement at the benefit level provided by Code Section 47-23-102, a member may retire at any time after attaining the age of 60 years and after obtaining a minimum of ten years of creditable service. The monthly retirement benefit for such early retirement shall be a percentage of the benefit under Code Section 47-23-100, and such percentage shall be the proportion which the number of years of creditable service the member has in the retirement system bears to 16.

(b) A member may retire pursuant to this Code section by making written application to the board setting forth at what time, not less than 30 days nor more than 90 days subsequent to the filing of such application, such member desires to be retired. All retirements shall be effective on the first day of the month following the month in which the member terminated his or her service.