An appeal may be brought against—
(a) any amendment of a self-assessment under section 9C of this Act (amendment by Revenue during enquiry to prevent loss of tax),
(b) any conclusion stated or amendment made by a closure notice under section 28A or 28B of this Act (amendment by Revenue on completion of enquiry into return),
(c) any amendment of a partnership return under section 30B(1) of this Act (amendment by Revenue where loss of tax discovered), or
(d) any assessment to tax which is not a self-assessment.
If an appeal under subsection (1)(a) above against an amendment of a self-assessment is made while an enquiry is in progress in relation to any matter to which the amendment relates or which is affected by the amendment none of the steps mentioned in section 49A(2)(a) to (c) may be taken in relation to the appeal until a partial closure notice is issued in relation to the matter or, if no such notice is issued, a final closure notice is issued.
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In the case of a simple assessment, the right to appeal under subsection (1)(d) does not apply unless and until the person concerned has—
(a) raised a query about the assessment under section 31AA, and
(b) been given a final response to that query.
This section has effect subject to any express provision in the Taxes Acts, including in particular any provision making one kind of assessment conclusive in an appeal against another kind of assessment.