California Code, Insurance Code - INS § 769.1

A commission payable to a broker-agent shall be at the rate and in accordance with the terms agreed to in writing between the insurer and the broker-agent.  There is a rebuttable presumption that a commission is lawful if it complies with the requirements of subdivisions (c) and (d) of Section 769 and subdivision (a) of Section 1861.16 and if it is paid in accordance with the written agreement.  The written agreement shall be consistent with Part 2 (commencing with Section 1549) of Division 3 of the Civil Code.  The presumption established by this section is a presumption affecting the burden of producing evidence.  This section applies to a written agreement entered into or modified on or after January 1, 2019.