21.—(1) The Commissioners may make a request to the complainant for any information which the Commissioners consider may be necessary to resolve the question in dispute by a mutual agreement procedure.
(2) That request may be made at any time during a mutual agreement procedure.
(3) The complainant must ensure that all the information requested by the Commissioners under paragraph (1) is provided to the Commissioners within the period of 90 days beginning with the date on which the complainant received the request.
(4) When that information is provided to the Commissioners, the complainant must ensure a copy of it is sent at the same time to each other competent authority concerned.
(5) But paragraph (4) does not apply where the affected person is an individual who, or a smaller undertaking which, is resident for tax purposes in the United Kingdom.
(6) In those cases, after the information is received by the Commissioners, the Commissioners must send a copy of it to each other competent authority concerned at the same time and without delay.
(7) If the complainant contravenes paragraphs (3) or (4)—
(a)the Commissioners may make an application to the competent court in respect of that contravention, and
(b)the competent court may order the complainant to comply with the requirements in those paragraphs.
(8) For the purposes of paragraph (1), the Commissioners may make as many requests as the Commissioners consider appropriate.