Cal. Government Code § 31870.3

Notwithstanding Section 31870.1, the board shall, before April 1st of each year, determine whether there has been an increase or decrease in the cost of living as provided in this section. Notwithstanding Section 31481 or any other provision of this chapter, every retirement allowance, optional death allowance, or annual death allowance payable to, or on account of, any member of this system who was covered under Section 31751 who retires or dies, or who has retired or died, shall, as of April 1st of each year, be increased or decreased by a percentage of the total allowance then being received found by the board to approximate to the nearest one-half of 1 percent, the percentage of annual increase or decrease in the cost of living as of January 1st of each year as shown by the then current Bureau of Labor Statistics Consumer Price Index for All Urban Consumers for the area in which the county seat is situated, but such change shall not exceed 4 percent per year; however, the amount of any cost of living increase or decrease in any year which is not met by the maximum annual change of 4 percent in allowances shall be accumulated to be met by increases or decreases in allowances in future years; except that no decrease shall reduce the allowance below the amount being received by the member or his beneficiary on the effective date of the allowance or the application of this section, whichever is later.