California Code, Government Code - GOV § 31873

(a) Any increases in contributions shall be shared equally between the county or district and the contributing members, with the individual member's contributions based upon the member's age at his or her nearest birthday at time of entrance into the retirement system or based on a single rate of contributions pursuant to Section 31621.11, 31639.26, or as otherwise authorized by this chapter or the California Public Employees' Pension Reform Act of 2013. The board of supervisors by a majority vote may elect to pay part of the costs of the contributions which would otherwise be assessed to the individual members.

(b) Notwithstanding subdivision (a), pursuant to Section 7522.30, the board of supervisors shall not pay any part of the costs of the member contributions of new members as defined in subdivision (f) of Section 7522.04.