21Limitation of refunds of revenue amounts

21 Limitation of refunds of revenue amounts (1) The commissioner must not refund a revenue amount unless the person claiming the refund (the claimant)— (a) satisfies the commissioner that— (i) the claimant has not charged to, or recovered from, any other person an amount paid in relation to the whole or any part of the revenue amount; or (ii) if the claimant has so charged or recovered any such amount—the claimant has repaid the amount; and (b) gives the commissioner a written undertaking that the claimant will not charge to, or recover from, any other person an amount paid in relation to the whole or any part of the revenue amount. (2) If the commissioner is not satisfied about the matters mentioned in subsection (1) (a), the commissioner must give the claimant written notice of his or her decision. (3) A person who contravenes an undertaking that the person has given under subsection (1) (b) is liable to pay the commissioner, as a penalty, an amount equal to double the amount that the person has charged to, or recovered from, another person by the contravention.