21(1)At any time when an enquiry is in progress into a return any question arising in connection with the subject-matter of the enquiry may be referred to the tribunal for determination.U.K.
(2)Notice of the referral must be given to the tribunal jointly by the filing member and an officer of Revenue and Customs.
(3)More than one notice of referral may be given in relation to an enquiry.
(4)An officer of Revenue and Customs or the filing member may withdraw a notice of referral.
(5)The effect of the notice being withdrawn is that the questions referred are not (unless they have already been finally determined) to be finally determined by the tribunal.
(6)While proceedings on a referral are in progress in relation to an enquiry—
(a)no closure notice may be given in relation to the enquiry, and
(b)no application may be made for a direction to give such a notice.
(7)Proceedings are in progress where—
(a)notice of referral has been given,
(b)the notice has not been withdrawn, and
(c)the questions referred have not been finally determined.
(8)In this paragraph, a question referred is finally determined when—
(a)it has been determined by the tribunal, and
(b)there is no further possibility of the determination being varied or set aside (disregarding any power to grant permission to appeal out of time).
(9)The determination of a question referred to the tribunal 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 under Part 12 of this Schedule.
(10)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.
(11)The question determined may not be reopened on an appeal under Part 12 of this Schedule, except to the extent that it could be reopened if it had been determined as a preliminary issue in that appeal.