(c) Beginning July 1, 1983, if death occurs prior to retirement on annuity and before the fireman's attainment of age 50, the amount of the benefit payable shall be $12,000. Beginning July 1, 1983, if death occurs prior to retirement, at age 50 or over, the benefit of $12,000 shall be reduced $400 for each year (commencing on the fireman's attainment of age 50 and thereafter on each succeeding birth date) that the fireman's age, at date of death, is more than age 49, but in no event below the amount of $6,000. Beginning July 1, 1983, if the fireman's death occurs while he is in receipt of an annuity, the benefit shall be $6,000.