20. Notwithstanding section 19, any lump sum paid as an increase or adjustment of the pensionable salary for a previous year shall form part of the pensionable salary of the year in which it is paid.
However, where the lump sum is paid in a year during which no service is credited, it shall be included in the pensionable salary of the last year during which service is credited to him prior to payment of the lump sum.
Any part of the lump sum that is attributable to an increase or adjustment of the salary paid to a pensioner for any period during which he is not an officer for the purposes of the plan provided for in this division, even if he holds pensionable employment under that plan, shall be excluded.
1973, c. 12, s. 154; 1977, c. 22, s. 8; 1982, c. 51, s. 82; 1983, c. 24, s. 63; 1987, c. 47, s. 120; 1987, c. 107, s. 234; 1988, c. 82, s. 99; 1990, c. 32, s. 37.