Cal. Insurance Code § 10089.9

(a) Upon commencement of participation in the authority, each participating insurer shall be required to execute a contract with the commissioner and the authority that sets forth its rights and responsibilities as an authority participant. The form of contract shall be part of the authority’s plan of operations and shall be uniform for every participating insurer. (b) The uniform authority participation contract required by subdivision (a) may be modified by the full execution of a writing, in a form drawn in accordance with this act, that embodies the mutual intent and understandings of the commissioner, the authority, and each participating insurer that has executed the authority participation contract. (c) In the event a nonparticipating insurer elects to become a participating insurer of the authority, the authority is authorized to present to the nonparticipating insurer the most recent form of the amended uniform authority participation contract it has executed or proposed to execute with existing participating insurers and require its execution as a condition of authority participation. The acceptance by the authority of, and reliance by the authority on, the executed amended authority participation contract that is authorized by this subdivision shall not be deemed a lack of the uniformity of contract required by subdivision (a).