13(1)The determination of a question referred to the tribunal under paragraph 10 is binding on the parties to the referral in the same way, and to the same extent, as a decision on a preliminary issue in an appeal.
(2)The determination must be taken into account by an officer of Revenue and Customs—
(a)in reaching the officer’s conclusions on the enquiry, and
(b)in formulating any amendments of the return required to give effect to those conclusions.
(3)The question determined may not be reopened on an appeal, except to the extent that it could be reopened if it had been determined as a preliminary issue in that appeal.