Cal. Bus. & Prof. Code § 17530.5
(a) It is a misdemeanor for any person, including an individual, firm, corporation, association, partnership, or joint venture, or any employee or agent thereof, to disclose any information obtained in the business of preparing federal or state income tax returns or assisting taxpayers in preparing those returns, including any instance in which this information is obtained through an electronic medium, unless the disclosure is within any of the following:
(b) For the purposes of this section, a person is engaged in the business of preparing federal or state income tax returns or assisting taxpayers in preparing those returns if the person does any of the following: