Mo. Rev. Stat. § 70.656

70.656. Final average compensation, period covered — governing body may elect — procedure — effects. — 1. Each political subdivision may, by majority vote of its governing body, elect, from time to time, with respect to its members retiring in the future, to have final average salary determined over a thirty-six-consecutive-month period instead of a sixty-consecutive-month period, as provided in subdivision (12) of section 70.600 . If a political subdivision makes no election under this section concerning final average salary, the sixty-consecutive-month period shall be in effect. The clerk or secretary of the political subdivision shall certify an election concerning final average salary to the board within ten days after such vote. The effective date of the political subdivision's final average salary election is the first day of the calendar month specified by such governing body, or the first day of the calendar month next following receipt by the board of the certification of final average salary election, or the effective date of the political subdivision's becoming an employer, whichever is the latest date. Such final average salary election may be changed from time to time by a majority vote of the governing body, but not more often than once in two years. If such changed final average salary provides larger allowances than the final average salary previously in effect, then such larger final average salary shall be applicable to the past and future employment with the employer by present and future employees. If such changed final average salary provides smaller allowances than the final average salary previously in effect, then such smaller final average salary shall be applicable only to credited service for employment rendered from and after the effective date of such change.

2. Should an employer change its final average salary election as provided in this section, the employer contributions shall be correspondingly changed effective the same date as the final average salary change.

3. The limitation on increases in an employer's contribution provided by subsection 6 of section 70.730 shall not apply to any contribution increase resulting from an employer electing a final average salary which provides larger allowances.

(L. 1984 H.B. 874, A.L. 1992 H.B. 1440)