17(1)An enquiry may extend to anything contained in the return, or required to be contained in the return, including anything that relates—U.K.
(a)to the question of whether multinational top-up tax is chargeable in respect of the accounting period, or
(b)to the amount of tax so chargeable.
(2)But, where the notice of enquiry is given in consequence of an amendment of a return—
(a)at a time when it is no longer possible to give a notice of enquiry under paragraph 16(2)(a) or (b),
(b)after a partial closure notice (see paragraph 22(1)) has been issued in relation to the matters to which the amendment relates or which are affected by the amendment, or
(c)after an enquiry into a return has been completed,
the enquiry into the return is limited to matters to which the amendment relates or that are affected by the amendment.