Cal. Elec. Code § 8901

For the purposes of this part, “income tax return” means any tax or information return, declaration of estimated tax, or claim for refund required by, or provided for or permitted under, the provisions of the Internal Revenue Code, and that is filed on behalf of, or with respect to, any person, and any amendment or supplement thereto, including supporting schedules, attachments, or lists that are supplemental to, or part of, the return so filed. For the purposes of this part, an “income tax return” does not include transcripts from the Internal Revenue Service nor accountant notes.