California Code, Business and Professions Code - BPC § 2406.5

(a) When a physician and surgeon, podiatrist, or other referring practitioner refers a patient to receive services by a physical therapist employed by a professional corporation as defined in Section 13401 of the Corporations Code, the referring practitioner shall comply with Article 6 (commencing with Section 650) of Chapter 1, and shall provide notice of the following to the patient, orally and in writing, in at least 14-point type and signed by the patient:

(b) This section shall not apply to a physician and surgeon, podiatrist, or other referring practitioner who is in a medical group with which a health care service plan, that is licensed pursuant to the Knox-Keene Health Care Service Plan Act of 1975 (Chapter 2.2 (commencing with Section 1340) of Division 2 of the Health and Safety Code) and is also exempt from federal taxation pursuant to Section 501(c)(3) of the Internal Revenue Code, exclusively contracts to provide professional medical services for its enrollees.