12(1)An officer of the Board shall not so amend an assessment made under section 9 of the Management Act (returns to include self-assessment) as to give effect to paragraph 3, 5 or 7 above unless a notice stating—
(a)in the case of paragraph 3 or 7 above, the aggregate of the amounts falling within sub-paragraph (1)(b) of that paragraph; and
(b)in the case of paragraph 5 above, the aggregate amount of interest paid as mentioned in sub-paragraph (3) of that paragraph,
is given by such an officer at a time when the condition mentioned in sub-paragraph (2) below is fulfilled.
(2)The condition referred to in sub-paragraph (1) above is that either—
(a)an assessment under section 9 of the Management Act has been made for the year 1998-99 and that assessment is still capable of being amended; or
(b)no such assessment has been so made.
(3)Subject to sub-paragraph (4) below, a notice under sub-paragraph (1) above shall be conclusive of the matters stated in it.
(4)An appeal may be brought against a notice under sub-paragraph (1) above at any time within the period of 30 days beginning with the date on which the notice is given.
(5)Subject to sub-paragraph (6) below, the provisions of the Management Act relating to appeals shall have effect in relation to an appeal under sub-paragraph (4) above as they have effect in relation to an appeal against an assessment to tax.
(6)On an appeal under sub-paragraph (4) above, section 50(6) to (8) of the Management Act (procedure on appeals) shall not apply but the Commissioners may—
(a)if it appears to them that the matters stated in the notice under sub-paragraph (1) above are correct, confirm the notice; or
(b)if it does not so appear to them, set aside or modify the notice accordingly.