Ed. Code, § 24408

(a) The minimum unmodified allowance, exclusive of annuities from accumulated annuity deposit and tax-sheltered contributions, of a person retired prior to January 1, 1981, shall be an amount equal to at least sixteen dollars ($16) per month multiplied by the years of credited service. This guaranteed amount shall be increased as of October 1, 1980, and shall be reduced by the amount of an unmodified allowance payable from a local system based on service credited under this part. If the retirement was effective at less than age 60 years, this allowance shall be reduced by one-half of 1 percent for each full month or fraction of a month that would have elapsed until the retired member would have reached age 60 years. If the retired member elected to have the allowance modified under Option 2 or 3, the increase in the retired member’s allowance shall be modified under the option selected.

(b) The board may make lump sum payments for increases between October 1, 1980, and January 1, 1981.