Section 15

Where the whole or any part of any levy or penalty under section 9 has not been paid, or after having been paid has been erroneously refunded, then, provided a demand is made within three years from the date on which such levy or penalty were paid, or the refund was made, as the case may be, the person liable to pay such levy or penalty, or the person to whom such refund has erroneously been made, as the case may be, shall pay the deficiency or repay the amount paid to him in excess.