Cal. Civil Code § 1799.1

(a) No business entity which performs bookkeeping services shall disclose in whole or in part the contents of any record, including the disclosure of information in the record in any composite of information, which is prepared or maintained by such business entity to any person, other than the individual or business entity which is the subject of the record, without the express written consent of such individual or business entity. (b) This section shall not apply to the following: (1) To a disclosure to any person pursuant to a subpoena or court order. (2) To a disclosure which is discoverable. (3) To a disclosure to any person acting pursuant to a lawful search warrant. (4) To a disclosure to a law enforcement agency when required for investigations of criminal activity, unless such disclosure is prohibited by law. (5) To a disclosure to a taxing agency for purposes of tax administration.