California Code, Government Code - GOV § 31511.6

General members may, within 180 days of the operative date of this article, elect to transfer to the retirement plan created by this article upon proper application executed by the member and filed with the board. Furthermore, any general member who does not elect to transfer during this 180-day period, may elect to transfer within the 30 days prior to any annual anniversary of the operative date of this article. Such a transfer is voluntary and shall be irrevocable.