Cal. Gov. Code § 3515.6

All employee organizations shall have the right to have membership dues, initiation fees, membership benefit programs, and general assessments deducted pursuant to subdivision (a) of Section 1152 and Section 1153 until such time as an employee organization is recognized as the exclusive representative for employees in an appropriate unit, and then such deductions as to any employee in the negotiating unit shall not be permissible except to the exclusive representative.