"1A – (1) Where – (a) the value of a supply made by a taxable person for a consideration is (apart from this sub-paragraph) less than its open market value, (b) the taxable person is a motor manufacturer or motor dealer, (c) the person to whom the supply is made is – (i) an employee of the taxable person, (ii) a person who, under the terms of his employment, provides services to the taxable person, or (iii) a relative of a person falling within sub-paragraph (i) or (ii) above, (d) the supply is a supply of services by virtue of sub-paragraph (4) or paragraph 5 of Schedule 4 (business goods put to private use etc), (e) the goods mentioned in that sub-paragraph consist of a motor car (whether or not any particular motor car) that forms part of the stock in trade of the taxable person, and (f) the supply is not one to which paragraph 1 above applies, the Commissioners may direct that the value of the supply shall be taken to be its open market value. (2) A direction under this paragraph shall be given by notice in writing to the person making the supply, but no direction may be given more than 3 years after the time of the supply."
"81 – (1) Where the services referred to in paragraph 5(4) of Schedule 4 to the Act are supplied for any period, they shall be treated as being supplied on the last day of the supplier's prescribed accounting period, or of each such accounting period, in which the goods are made available or used."