California Code, Government Code - GOV § 22890

(a) The contracting agency and each employee or annuitant shall contribute a portion of the cost of providing the benefit coverage afforded under the health benefit plan approved or maintained by the board in which the employee or annuitant may be enrolled.

(b) An annuitant is entitled to only one employer contribution. If more than one annuitant is receiving an allowance as the survivor of the same employee or annuitant, there shall be only one employer contribution with respect to all such annuitants.

(c) The contribution of each employee and annuitant shall be the total cost per month of the benefit coverage afforded him or her under the health benefit plan or plans in which he or she is enrolled less the portion thereof to be contributed by the employer. The employer contribution for each employee and annuitant shall commence on the effective date of enrollment.