(a) A member may retire with full benefits upon attaining the age of fifty and completing twenty-five or more years of service or attaining the age of fifty-two and completing twenty years or more of service by filing with the board his or her voluntary application in writing for retirement. A member who is less than age fifty-two may retire upon completing twenty years or more of service: Provided, That he or she will receive a reduced benefit that is of equal actuarial value to the benefit the member would have received if the member deferred commencement of his or her accrued retirement benefit to the age of fifty-two.
(b) When the board retires a member with full benefits under the provisions of this section, the board, by order in writing, shall make a determination that the member is entitled to receive an annuity equal to two and three-fourths percent of his or her final average salary multiplied by the number of years, and fraction of a year, of his or her service at the time of retirement, subject to reduction if necessary to comply with the maximum benefit provisions of Section 415 of the Internal Revenue Code and section six-a of this article. The retirant's annuity shall begin the first day of the calendar month following the month in which the member's application for the annuity is filed with the board on or after his or her attaining age and service requirements and termination of employment.
(c) In no event may the provisions of section thirteen, article sixteen, chapter five of this code be applied in determining eligibility to retire with either a deferred or immediate commencement of benefit.