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HMRC internal manual

Self Assessment Claims Manual

HM Revenue & Customs
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Appendix 1: Old Error or Mistake Relief: Assessments Determined on Appeal

From 1 April 2010, it is not possible to make a claim for the old error or mistake relief for any period. The relief is replaced by overpayment relief, see SACM12000+. You will only need the guidance in SACM Appendix 1 if you are dealing with a claim made before 1 April 2010.

An application for relief should not be regarded as precluded merely by reason of the fact that the amount of the assessment has been fixed on appeal. But relief will not be available where the substantive point of an error or mistake claim was squarely in issue before the tribunal when the appeal was determined. In the circumstances the tribunal’s determination of the point is final and conclusive (TMA70/S46 (2)).

Similarly, relief will not be available where the substantive point was squarely in issue in the process of reaching agreement and determining the appeal under TMA70/S54. Again the determination of the point is final and conclusive, TMA70/S54 (1) directs that the like consequences shall ensue as if the tribunal had determined the appeal (see Eagerpath Ltd v Edwards TL3623).

In addition the assessment for the year (even if later proved to be excessive) is not excessive by reason of some error or mistake in a taxpayer’s return (see SACM20040), but by reason of the taxpayer’s failure to pursue his arguments on the point squarely in issue through the normal appeal channels.