“39. Regulation 107B enacts the standard method override which was introduced by HMRC in exercise its powers undersection 26 of the VAT Act 1994 to counter avoidance schemes based on the standard method and to deal with situations where the result of the method is clearly unreasonable. Under regulation 107B a provisional attribution of input tax to taxable supplies for a long period under regulation 107 (1)(a) shall be adjusted if the attribution differs substantially from one which represents the extent to which the goods or services are used in the making of taxable supplies. Regulation 107 defines the threshold of£50,000 or 50% of the input tax for a substantial difference. 40. The above analysis of the legislation dealing with the right to deduct demonstrates that its overriding purpose is to ensure that the right to deduction is confined to input tax attributable to taxable supplies. In domestic legislation this purpose is achieved by detailed regulations enacted under section 26(3) of the VAT 1994 which requires the regulations to secure a fair and reasonable attribution of input tax to taxable supplies. The regulations achieve this by identifying a method for attributing input tax to taxable supplies including the apportionment of residual input tax between taxable and exempt supplies and by requiring the taxpayer to carry out the attributions every quarter followed by an annual adjustment. The de minimus limits in regulation 106 come into play after the calculation of the deductible input tax in accordance with the standard method has been completed for each period. Regulation 106 applies to relevant input tax. Regulation 106(3) defines relevant input tax as input tax attributed to exempt supplies which can only be known at the end of the calculation arising from the standard method.”