Cal. Rev. & Tax. Code § 19394

If the fee provided under Section 17942 is finally adjudged to be discriminatory or unfairly apportioned under the California Constitution, or the laws or the Constitution of the United States, the fee of a disfavored taxpayer that files, or has filed, a timely claim for refund within the period allowed by this part asserting discrimination or unfair apportionment shall be recomputed by the Franchise Tax Board for the taxable year in question, as of the time of allowance of the recomputation, only to the extent necessary to remedy the discrimination or unfair apportionment that is not otherwise relieved by Section 19393 and the amount of the fee, as originally computed, shall be subject to the provisions hereof relating to original computations.