In any case where—
(a)an amount is due from the Commissioners to any person under the [1983 c. 55.] Value Added Tax Act 1983 or Chapter II of Part I of the [1985 c. 54.] Finance Act 1985; and
(b)that person is liable to pay a sum by way of tax, penalty, interest or surcharge,
the amount referred to in paragraph (a) above shall be set against the sum referred to in paragraph (b) above and, accordingly, to the extent of the set-off, the obligations of the Commissioners and the person concerned shall be discharged.