Cal. Rev. & Tax. Code § 19385

If the Franchise Tax Board fails to mail notice of action on any refund claim within six months after the claim was filed, the taxpayer may, prior to mailing of notice of action on the refund claim, consider the claim disallowed and bring an action against the Franchise Tax Board on the grounds set forth in the claim for the recovery of the whole or any part of the amount claimed as an overpayment. For substitution of the 120-day period for the six-month period contained in this section in a Title 11 case, see Section 505(a)(2) of Title 11 of the United States Code.