If the Supreme Court determines that the assessment or tax is excessive, it shall reduce the same or if it is insufficient, it shall increase the same. Unless the taxes so assessed or ascertained were paid under protest, when due, the Court, if it disallows the claim, on the appeal of the taxpayer, shall, in upholding the assessment, give judgment against such taxpayer for the taxes so assessed and ascertained and for a sum, by way of damages, equal to interest at the rate of one percent a month upon the amount of the taxes from the time the same were payable.

If the decision is in favor of the taxpayer, in whole or in part, appropriate relief shall be granted, including the right to recover any excess of taxes that have been paid, with legal interest thereon and with the costs incurred by such taxpayer, from the Commonwealth or local authorities, or both, as the case may be, the judgment to be enforceable by mandamus or other proper process issuing from the Court.

If the decision be in favor of the Commonwealth or of any county, city or town, appropriate relief shall be granted and enforced by mandamus or other proper process issuing from the Court.

The Court may, when deemed proper so to do, return the case to the Commission for further proceedings, either by way of hearing or for appropriate remedy.