Cal. Gov't Code § 21357

(a) For a member reinstated from service retirement or partial service retirement, the current service pension, or current and prior service pensions, as the case may be, upon his or her service retirement subsequent to the reinstatement, shall be the sum of (1) a current service pension calculated on the basis of service rendered after reinstatement in accordance with the formula applicable to him or her in that service and membership, plus, (2) 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, or if the subsequent service or disability retirement occurs after his or her reinstatement from service or disability retirement pursuant to an election under Section 21465 or 21483, his or her current service pension, or current and prior service pensions, as the case may be, as it was 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 for which he or she was retired, and further adjusted according to any change after reinstatement in the provisions governing the calculation of his or her pension that would have applied to him or her had he or she continued in retirement but been subject to the formula applied in the first adjustment; or, for state miscellaneous and state industrial service subject to Section 21076, in lieu of (2), plus (3) a current service pension, or current and prior service pensions, as the case may be, as it would have been prior to his or her reinstatement under the formula applicable to Section 21076, 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 for which he or she was retired, and further adjusted according to any change after reinstatement in the provisions governing the calculations of his or her pension that would have applied to him or her had he or she continued in retirement and been subject to the formula applicable to Section 21076, or if he or she has rendered one year or more of state service after reinstatement, in lieu of (2) or (3), plus (4), a current service pension based on current service rendered prior to reinstatement, calculated on the basis of the formula currently applicable to the employment in which the service was rendered but 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 a member reinstated from nonindustrial disability retirement, the current 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 credited under this system 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.
(b) The current 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 (converted as below), if any, by which:
1. (1) The total amount paid in the period during which a temporary annuity was included in the payments, reduced by the total amount that would have been payable during that period had the election not been made, exceeds
2. (2) The excess of the total amount that would have been payable, had the election not been made, during the time subsequent to that period and prior to reinstatement, over the total amount actually paid during that time.
  The amount determined by the above formula shall be converted to an amount equaling the actuarial equivalent on the date of reinstatement and this 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.
(c) Notwithstanding this section, or any other provision of this part, the current 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 current service pension was paid prior to reinstatement shall not be less than the current service pension that would be payable on the date of the subsequent retirement had the member not been reinstated. For state miscellaneous and state industrial service subject to Section 21076, the current service pension payable for any credited service for which a current service pension was paid prior to reinstatement shall not be less than the current service pension that would have been payable on the date of the subsequent retirement had the member’s retirement been subject to the formula under Section 21076 and had 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.