California Code, Business and Professions Code - BPC § 5055

Any person who has received from the board a certificate of certified public accountant, or who is authorized to practice public accountancy in this state pursuant to Article 5.1 (commencing with Section 5096), may, subject to Section 5051, be styled and known as a “certified public accountant” and may also use the abbreviation “C.P.A.” No other person, except a firm registered under this chapter, shall assume or use that title, designation, or abbreviation or any other title, designation, sign, card, or device tending to indicate that the person using it is a certified public accountant.