Cal. Civ. Proc. Code § 1263.520

The owner of a business who claims compensation under this article shall make available to the court, and the court shall, upon such terms and conditions as will preserve their confidentiality, make available to the plaintiff, the state tax returns of the business for audit for confidential use solely for the purpose of determining the amount of compensation under this article. Nothing in this section affects any right a party may otherwise have to discovery or to require the production of documents, papers, books, and accounts.