Cal. Gov. Code § 21385
The prior service pension of a member reinstated from service retirement, upon his or her subsequent service retirement, shall be in the same amount as his or her prior service pension prior to his or her reinstatement, adjusted for any service on which the pension was based that was included in coverage of the federal system during reinstatement according to the formula applicable to the service in employment from which he or she was retired, and further adjusted according to any change in the provisions governing the calculation of the pensions, using the formula applied in the first adjustment, made after the reinstatement and applicable to pensions being paid at the date of the change if the subsequent retirement occurs before he or she renders after his or her reinstatement at least one year of state service credited under this system. Otherwise, the prior service pension calculated on the basis of an age, taken to the preceding completed quarter year but not less than the minimum retirement age applicable to him or her at his or her last retirement, and determined by deducting from his or her age at his or her subsequent retirement, the aggregate time during which he or she was under retirement. For such a member reinstated from nonindustrial disability retirement, the prior service pension upon his or her service retirement after attaining an age one year less than the minimum age at which he or she could have retired without an actuarial discount because of age in the employment from which he or she was last retired, or upon his or her disability retirement after attaining the minimum age, and subsequent to reinstatement, shall be calculated in the manners described in the preceding sentence, but the age determined upon subsequent retirement after rendering at least one year of state service, shall not be taken at less than one year less than the minimum age if the subsequent retirement is for service, or the minimum age if the retirement is for disability.
The prior service pension otherwise payable under this section to a member whose allowance prior to reinstatement was paid pursuant to his or her election under Section 21461, 21461.5, 21479, or 21480 shall be reduced by the actuarial equivalent, on the date of retirement subsequent to reinstatement, of the amount, if any (converted as below), by which:
The amount determined by the above formula shall be converted to an amount equaling the actuarial equivalent on the date of reinstatement. The latter amount shall be the basis of the actuarial equivalent, on the date of retirement subsequent to reinstatement.
Actuarial equivalents required by this section shall be based on the interest rate and mortality tables in use by this system on the date of retirement subsequent to reinstatement.
Notwithstanding this section, or any other provision of this part, the prior service pension payable to any member subject to this section who rendered one year or more of state service credited under this system after reinstatement on retirement for service subsequent to reinstatement from service retirement for any credited service for which a prior service pension was paid prior to reinstatement shall not be less than the prior service pension that would be payable on the date of the subsequent retirement had the member not been reinstated, adjusted, however, by any reduction under this section because of an election under Section 21461, 21461.5, 21479, or 21480 and, for any service so credited that was included in coverage of the federal system during reinstatement, according to the formula applicable to the service in employment from which he or she was retired.
Ca. Gov. Code § 21385