If:
(a) a person pays an amount to the Commonwealth under this Subdivision; and
(b) the amount exceeds the sum of:
(i) the amount required to discharge the total debt that the person owed to the Commonwealth under this Part; and
(ii) the total amount of the person's primary tax debts (within the meaning of Part IIB of the Taxation Administration Act 1953 );
the Commonwealth must refund to the person an amount equal to that excess.