18(1)Where a person is found liable for a penalty under paragraph 1 HMRC must—
(a)assess the penalty,
(b)notify the person, and
(c)state in the notice—
(i)the uncorrected relevant offshore tax non-compliance to which the penalty relates, and
(ii)the tax period to which that offshore tax non-compliance relates.
(2)A penalty must be paid before the end of the period of 30 days beginning with the day on which notification of the penalty is issued.
(3)An assessment of a penalty—
(a)is to be treated for procedural purposes in the same way as an assessment to tax (except in respect of a matter expressly provided for by this Schedule),
(b)may be enforced as if it were an assessment to tax, and
(c)may be combined with an assessment to tax.
(4)A supplementary assessment may be made in respect of a penalty if an earlier assessment operated by reference to an underestimate of the liability to tax that would have been shown in a return.
(5)Sub-paragraph (6) applies if—
(a)an assessment in respect of a penalty is based on a liability to offshore tax that would have been shown on a return, and
(b)that liability is found by HMRC to have been excessive.
(6)HMRC may amend the assessment so that it is based upon the correct amount.
(7)But an amendment under sub-paragraph (6)—
(a)does not affect when the penalty must be paid, and
(b)may be made after the last day on which the assessment in question could have been made under paragraph 19.