Cal. Rev. & Tax. Code § 19348

If the Franchise Tax Board fails to mail notice of action of disallowance of interest on any refund claim within six months after the interest was claimed, the taxpayer may, prior to mailing notice of action of disallowance of interest on the refund claim, consider the interest disallowed and bring an action against the Franchise Tax Board on the grounds set forth for interest in the claim for the recovery of the interest.