Cal. Gov't Code § 7522.30

(a) This section shall apply to all public employers and to all new members. Equal sharing of normal costs between public employers and public employees shall be the standard. The standard shall be that employees pay at least 50 percent of normal costs and that employers not pay any of the required employee contribution.
(b) The “normal cost rate” shall mean the annual actuarially determined normal cost for the plan of retirement benefits provided to the new member and shall be established based on the actuarial assumptions used to determine the liabilities and costs as part of the annual actuarial valuation. The plan of retirement benefits shall include any elements that would impact the actuarial determination of the normal cost, including, but not limited to, the retirement formula, eligibility and vesting criteria, ancillary benefit provisions, and any automatic cost-of-living adjustments as determined by the public retirement system.
(c) New members employed by those public employers defined in paragraphs (2) and (3) of subdivision (i) of Section 7522.04, the Legislature, the California State University, and the judicial branch who participate in a defined benefit plan shall have an initial contribution rate of at least 50 percent of the normal cost rate for that defined benefit plan, rounded to the nearest quarter of 1 percent, unless a greater contribution rate has been agreed to pursuant to the requirements in subdivision (e). This contribution shall not be paid by the employer on the employee’s behalf.
(d) Notwithstanding subdivision (c), once established, the employee contribution rate described in subdivision (c) shall not be adjusted on account of a change to the normal cost rate unless the normal cost rate increases or decreases by more than 1 percent of payroll above or below the normal cost rate in effect at the time the employee contribution rate is first established or, if later, the normal cost rate in effect at the time of the last adjustment to the employee contribution rate under this section.
(e) Notwithstanding subdivision (c), employee contributions may be more than one-half of the normal cost rate if the increase has been agreed to through the collective bargaining process, subject to the following conditions:
1. (1) The employer shall not contribute at a greater rate to the plan for nonrepresented, managerial, or supervisory employees than the employer contributes for other public employees, including represented employees, of the same employer who are in related retirement membership classifications.
2. (2) The employer shall not increase an employee contribution rate in the absence of a memorandum of understanding that has been collectively bargained in accordance with applicable laws.
3. (3) The employer shall not use impasse procedures to increase an employee contribution rate above the rate required by this section.
(f) If the terms of a contract, including a memorandum of understanding, between a public employer and its public employees, that is in effect on January 1, 2013, would be impaired by any provision of this section, that provision shall not apply to the public employer and public employees subject to that contract until the expiration of that contract. A renewal, amendment, or any other extension of that contract shall be subject to the requirements of this section.