Cal. Education Code § 23203

(a) A member who elects to redeposit refunded accumulated retirement contributions shall pay, prior to retirement, all contributions and interest as determined under Section 23200. (b) If the system is unable to inform the member or beneficiary of the amount required to redeposit the refunded accumulated retirement contributions prior to the effective date of the applicable allowance, the member or beneficiary may make the required payment within 30 working days after the date of mailing of the statement of contributions and interest required or the effective date of the appropriate allowance, whichever is later, except as provided in subdivision (d). The payment shall be paid in full before a member or beneficiary receives any adjustment in the appropriate allowance due because of that payment. (c) Redeposit of refunded accumulated retirement contributions shall be made in one sum, or in not more than 120 monthly installments, not to exceed ten years, provided that no installment, except the final installment, is less than twenty-five dollars ($25). (d) The measurement of time within which a redeposit described in subdivision (b) shall be made is subject to Section 22337.