California Code, Government Code - GOV § 20327

(a) Notwithstanding any other provision of this part, a National Guard member may, at any time and on a prospective basis, cancel his or her election of membership in this system by filing a written notice of cancellation with the board.

(b) If a National Guard member cancels his or her election of membership, that National Guard member shall not be required to pay contributions as described in Section 20772.5, effective as of the date the written notice of cancellation was filed with the board.

(c) A National Guard member may only elect to cancel his or her membership pursuant to this section one time.

(d) This section shall remain operative until subsequent provisions of law delete the requirement that National Guard members pay the employer contributions as a condition of membership in this system.