“(1) If an officer of the Board or the Board discover, as regards any person (the taxpayer) and a year of assessment— (a) that any income which ought to have been assessed to income tax, or chargeable gains which ought to have been assessed to capital gains tax, have not been assessed, or (b) that an assessment to tax is or has become insufficient, or (c) that any relief which has been given is or has become excessive, the officer or, as the case may be, the Board may, subject to subsections (2) and (3) below, make an assessment in the amount, or the further amount, which ought in his or their opinion to be charged in order to make good to the Crown the loss of tax. (2) … (3) Where the taxpayer has made and delivered a return under section 8 or 8A of this Act in respect of the relevant year of assessment, he shall not be assessed under subsection (1) above— (a) in respect of the year of assessment mentioned in that subsection; and (b) ... in the same capacity as that in which he made and delivered the return, unless one of the two conditions mentioned below is fulfilled. (4) …. (5) The second condition is that at the time when an officer of the Board— (a) ceased to be entitled to give notice of his intention to enquire into the taxpayer's return under section 8 or 8A of this Act in respect of the relevant year of assessment; or (b) informed the taxpayer that he had completed his enquiries into that return, the officer could not have been reasonably expected, on the basis of the information made available to him before that time, to be aware of the situation mentioned in subsection (1) above. (6) For the purposes of subsection (5) above, information is made available to an officer of the Board if— (a) it is contained in the taxpayer's return under section 8 or 8A of this Act in respect of the relevant year of assessment (the return), or in any accounts, statements or documents accompanying the return; (b) it is contained in any claim made as regards the relevant year of assessment by the taxpayer acting in the same capacity as that in which he made the return, or in any accounts, statements or documents accompanying any such claim; (c) it is contained in any documents, accounts or particulars which, for the purposes of any enquiries into the return or any such claim by an officer of the Board, are produced or furnished by the taxpayer to the officer, whether in pursuance of a notice under section 19A of this Act or otherwise; or (d) it is information the existence of which, and the relevance of which as regards the situation mentioned in subsection (1) above— (i) could reasonably be expected to be inferred by an officer of the Board from information falling within paragraphs (a) to (c) above; or (ii) are notified in writing by the taxpayer to an officer of the Board. (7) In subsection (6) above— (a) any reference to the taxpayer's return under section 8 or 8A of this Act in respect of the relevant year of assessment includes— (i) a reference to any return of his under that section for either of the two immediately preceding chargeable periods; and (ii) where the return is under section 8 and the taxpayer carries on a trade, profession or business in partnership, a reference to any partnership return with respect to the partnership for the relevant year of assessment or either of those periods; and (b) any reference in paragraphs (b) to (d) to the taxpayer includes a reference to a person acting on his behalf. (8) An objection to the making of an assessment under this section on the ground that neither of the two conditions mentioned above is fulfilled shall not be made otherwise than on an appeal against the assessment. (9) Any reference in this section to the relevant year of assessment is a reference to— (a) in the case of the situation mentioned in paragraph (a) or (b) of subsection (1) above, the year of assessment mentioned in that subsection; and (b) in the case of the situation mentioned in paragraph (c) of that subsection, the year of assessment in respect of which the claim was made.”