Cal. Education Code § 24410

(a) If projected final compensation is used to calculate the service retirement allowance following the termination of the disability allowance or if the disability allowance is continued as the lesser of the two allowance calculations under Section 24212 or 24213, then the original disability allowance effective date shall be retained as the base date for purposes of determining postretirement benefit increases. (b) If the disability allowance effective date is used pursuant to subdivision (a), then for purposes of determining supplemental benefits pursuant to Sections 24412 and 24415, the base allowance shall be determined as follows: (1) If the disability allowance is continued pursuant to Section 24212 or 24213, the base allowance shall be equal to the disability allowance prior to all allowance increases made pursuant to this part. (2) If the disability allowance is not continued pursuant to Section 24212 or 24213, the base allowance shall be based on the factors used to calculate the service retirement allowance, except that projected final compensation shall be replaced with the final compensation upon which the disability allowance was based. (3) The base allowance determined pursuant to this subdivision shall be modified for an option, if applicable. (c) This section shall be applicable for determining the base date for applicable postretirement increases made on or after January 1, 1982. (d) This section shall only apply to service retirements effective the day after the termination date of the disability allowance.