Cal. CORP § 13405

(a) Subject to the provisions of Section 13404, a professional corporation may lawfully render professional services in this state, but only through employees who are licensed persons. The corporation may employ persons not so licensed, but such persons shall not render any professional services rendered or to be rendered by that corporation in this state. A professional corporation may render professional services outside of this state, but only through employees who are licensed to render the same professional services in the jurisdiction or jurisdictions in which the person practices. Nothing in this section is intended to prohibit the rendition of occasional professional services in another jurisdiction as an incident to the licensee’s primary practice, so long as it is permitted by the governing agency that regulates the particular profession in the jurisdiction. Nothing in this section is intended to prohibit the rendition of occasional professional services in this state as an incident to a professional employee’s primary practice for a foreign professional corporation qualified to render professional services in this state, so long as it is permitted by the governing agency that regulates the particular profession in this state.

(b) Subject to Section 13404.5, a foreign professional corporation qualified to render professional services in this state may lawfully render professional services in this state, but only through employees who are licensed persons, and shall render professional services outside of this state only through persons who are licensed to render the same professional services in the jurisdiction or jurisdictions in which the person practices. The foreign professional corporation may employ persons in this state who are not licensed in this state, but those persons shall not render any professional services rendered or to be rendered by the corporation in this state.

(c) Nothing in this section or in this part is intended to, or shall, augment, diminish or otherwise alter existing provisions of law, statutes or court rules relating to services by a California attorney in another jurisdiction, or services by an out-of-state attorney in California. These existing provisions, including, but not limited to, admission pro hac vice and the taking of depositions in a jurisdiction other than the one in which the deposing attorney is admitted to practice, shall remain in full force and effect.