17(1)For the purposes of paragraph 15 above, any question whether the person by whom a trade, profession or vocation is carried on is connected with another person shall be determined in accordance with sub-paragraphs (2) to (5) below.
(2)An individual carrying on a trade, profession or vocation is connected with another person if they are connected with each other within the meaning of section 839 of the Taxes Act 1988 (disregarding for this purpose the exception in subsection (4) of that section).
(3)Persons carrying on a trade or profession in partnership are connected with an individual if he controls the partnership.
(4)Persons carrying on a trade or profession in partnership are connected with a company if the company controls the partnership or the same person controls both the company and the partnership.
(5)Persons carrying on a trade or profession in partnership are connected with persons carrying on another trade or profession in partnership if the same person controls both partnerships.
(6)In this paragraph—
(a)“control” shall be construed—
(i)in relation to a company, in accordance with section 416 of the Taxes Act 1988;
(ii)in relation to a partnership, in accordance with section 840 of that Act; and
(b)any reference to a person controlling a company or partnership is a reference to his doing so either alone or with one or more persons connected with him.