Cal. Business and Professions Code § 5807

(a) A Certified Interior Designer shall use a written contract when contracting to provide interior design services to a client pursuant to this chapter. The written contract shall be executed by the Certified Interior Designer and the client, or the client’s representative, prior to the Certified Interior Designer commencing work. The written contract shall include, but not be limited to, all of the following: (1) A description of the services to be provided to the client by the Certified Interior Designer. (2) A description of any basis of compensation applicable to the contract and the method of payment agreed upon by the parties. (3) The name, address, and certification number of the Certified Interior Designer and the name and address of the client. (4) A description of the procedure that the Certified Interior Designer and the client will use to accommodate additional services. (5) A description of the procedure to be used by any party to terminate the contract. (6) A three-day rescission clause in accordance with Chapter 2 (commencing with Section 1688) of Title 5 of Part 2 of Division 3 of the Civil Code. (7) A written disclosure stating whether the Certified Interior Designer carries errors and omissions insurance. (b) Subdivision (a) shall not apply to any of the following: (1) Interior design services rendered by a Certified Interior Designer for which the client will not pay compensation. (2) Interior design services rendered by a Certified Interior Designer to any of the following: (A) An architect licensed under Chapter 3 (commencing with Section 5500). (B) A landscape architect licensed under Chapter 3.5 (commencing with Section 5615). (C) An engineer licensed under Chapter 7 (commencing with Section 6700). (c) As used in this section, “written contract” includes a contract in electronic form.