Cal. Gov. Code § 20910

A member whose right to elect to receive service credit pursuant to Article 4 (commencing with Section 20990) and Article 5 (commencing with Section 21020) has been awarded in part to a nonmember, pursuant to paragraph (4) of subdivision (c) of Section 21290, may elect to receive service credit for the same amount and type of service credit that the nonmember is entitled to purchase, if the nonmember has permanently waived all rights in the system by effecting a refund of accumulated contributions pursuant to Section 21292. A member electing to receive service credit pursuant to this section shall make the contributions required under this chapter for the particular amount and type of service credit.