Cal. Government Code § 7522.44

This section shall apply to all public employers and to all public employees: (a) Any enhancement to a public employee’s retirement formula or retirement benefit adopted on or after January 1, 2013, shall apply only to service performed on or after the operative date of the enhancement and shall not be applied to any service performed prior to the operative date of the enhancement. (b) If a change to a member’s retirement membership classification or a change in employment results in an enhancement in the retirement formula or retirement benefit applicable to that member, that enhancement shall apply only to service performed on or after the operative date of the change and shall not be applied to any service performed prior to the operative date of the change. (c) For purposes of this section, “operative date” in a collective bargaining agreement means one of the following: (1) The date that the agreement is signed by the parties. (2) A date agreed to by the parties that will occur after the date that the agreement is signed by the parties. (3) A date designated by the parties that occurred prior to the date the agreement was signed if the most recent collective bargaining contract was expired at the time of the agreement and the date designated is not earlier than 12 months prior to the date of the agreement or the day after the last day of the expired bargaining contract, whichever occurred later. (d) For purposes of this section, an increase to a retiree’s annual cost-of-living adjustment within existing statutory limits shall not be considered to be an enhancement to a retirement benefit.