California Code, Government Code - GOV § 9357.46

Any person who was a member and who withdrew his or her accumulated contributions after discontinuance of service may, at any time while he or she is in employment in which he or she is a member of the Public Employees' Retirement System or the State Teachers' Retirement System, redeposit into the fund in one sum an amount equal to the accumulated contributions withdrawn plus the interest that would have been credited to those accumulated contributions had they not been withdrawn, using the rate of interest in effect at the time of redeposit.

Upon the redeposit, the person shall become a member with the rights provided a member who elected under Section 9355.2 to allow his or her contributions to remain in the fund.