The following allowances due under the provisions of sections 87.120 to 87.370 of any member who retired from service shall be increased annually, as approved by the board of trustees beginning with the first increase in the October following his retirement and subsequent increases in each October thereafter, at the rates designated:

1. (1) With a retirement service allowance or ordinary disability allowance

   1. (a) One and one-half percent per year, compounded each year, up to age sixty for those retiring with twenty to twenty-four years of service,
   2. (b) Two and one-fourth percent per year, compounded each year, up to age sixty for those retiring with twenty-five to twenty-nine years of service,
   3. (c) Three percent per year, compounded each year, up to age sixty for those retiring with thirty or more years of service,
   4. (d) After age sixty, five percent per year for five years or until a total maximum increase of twenty-five percent is reached;

2. (2) With an accidental disability allowance, three percent per year, compounded each year, up to age sixty, then five percent per year for five years or until a total maximum increase of twenty-five percent is reached.

   ­­­Each increase, however, is subject to a determination by the board of trustees that the consumer price index (United States Average Index) as published by the United States Department of Labor shows an increase of not less than the approved rate during the latest twelve-month period for which the index is available at date of determination. If the increase is in excess of the approved rate for any year, the excess shall be accumulated as to any retired member and increases may be granted in subsequent years subject to the maximum allowed for each full year from October following his retirement but not to exceed a total increase of twenty-five percent. If the board of trustees determines that the index has decreased for any year, the benefits of any retired member that have been increased shall be decreased but not below his initial benefit. No annual increase shall be made of less than one percent and no decrease of less than three percent except that any decrease shall be limited by the initial benefit.

(L. 1969 p. 163 § 1, A.L. 1973 H.B. 591, A.L. 1983 H.B. 694 & 171)

(1975) Held an increase in pensions for persons already retired based on cost of living violates article VI, § 25, Constitution of Missouri, and that pension funds retain their identity as public funds. Section 86.441 insofar as it applies to persons already retired on August 13, 1972, is unconstitutional. Police Retirement System v. Kansas City (Mo.), 529 S.W.2d 388.