California Code, Government Code - GOV § 9355.2

Notwithstanding any other provision of this chapter, if the service of a member is discontinued by any means other than death or retirement pursuant to this chapter, he or she shall have the right to elect not later than 90 days after the date upon which notice of that right is mailed by this system by registered mail to the member's latest address on file in the office of this system, and without right of revocation, whether to allow his or her accumulated contributions to remain in the fund.  Failure to make that election shall be deemed an irrevocable election to resign from this system and withdraw his or her accumulated contributions.  A member whose membership continues under this section is subject to the same age requirements as apply to other members for retirement, and upon qualification for retirement by age, he or she shall, upon his or her application therefor to the board, be retired, and receive a retirement allowance based upon the service with which he or she is credited, in the same manner as other members of this system.