Cal. Gov. Code § 21576
This article applies from and after January 1, 1960, or the date of a member's subsequent election, to state members and local miscellaneous members who are employees of school districts that are contracting agencies, or who are included in this system under Chapter 6 (commencing with Section 20610), who entered or enter membership after November 4, 1959, or who were members on November 4, 1959, and elected, pursuant to rules of the board, to be subject to this article, or who so elect within 90 days following October 1, 1961, in the manner prescribed. This article shall not apply to any member with respect to service that is included in the federal system.
An election pursuant to this section shall be in writing and shall be effective only when received in the office of the board. Contributions under this article for the member shall begin on the first of the month or the payroll period following the filing of the election. The board may, on the request of any member who on November 4, 1959, elected to be subject to this article, cancel the election if it finds that the election was made because of the member's mistake or misunderstanding, and that the member has acted diligently in making the request. The cancellation shall be effective as of the first day of the month following the board's action canceling the election.
Ca. Gov. Code § 21576