“Subject to section 84, an appeal shall lie to a tribunal with respect to any of the following matters...”
“1. The Commissioners' opinion referred to in section 73(6)(b) is an opinion as to whether they have evidence of facts sufficient to justify making the assessment. Evidence is the means by which the facts are proved. 2. The evidence in question must be sufficient to justify the making of the assessment in question: C & E Commissioners v Post Office[1995] STC 749 , 754G. 3. The knowledge referred to in section 73(6)(b) is actual, and not constructive knowledge: C & E Commissioners v Post Office at p755D. In this context, I understand constructive knowledge to mean knowledge of evidence which the Commissioners do not in fact have, but which they could and would have if they had taken the necessary steps to acquire it. 4. The correct approach for a Tribunal to adopt is (i) to decide what were the facts which, in the opinion of the officer making the assessment on behalf of the Commissioners, justified the making of the assessment, and (ii) to determine when the last piece of evidence of these facts of sufficient weight to justify making the assessment was communicated to the Commissioners. The period of one year runs from the date in (ii): Heyfordian Travel Ltd v C & E Commissioners [1979] VATTR 139,151; and Classicmoor Ltd v C & E Commissioners [1995] V &DR 1, 10.I.27. 5. An officer's decision that the evidence of which he has knowledge is insufficient to justify making an assessment, and accordingly, his failure to make an earlier assessment, can only be challenged on Wednesbury principles, or principles analogous to Wednesbury: Classicmoor paras 27 to 29; and more generally John Dee Ltd v C & E Commissioners[1995] STC 941 , 952D-H. 6. The burden is on the taxpayer to show that the assessment was made outside the time limit specified in section 73(6)(b) of VATA.”
“The element of guesswork and the almost unavoidable inaccuracy in a properly made best of judgment assessment, as the cases have established, do not serve to displace the validity of the assessments, which are prima facie right and remain right until the taxpayer shows that they are wrong and also shows positively what corrections should be made in order to make the assessments right or more nearly right." (Bi−Flex Caribbean Ltd v Board of Inland Revenue (1990) 63 TC 515, 522−3 PC, per Lord Lowry).”