(1)Subsections (5) and (6) apply if—
(a)under double taxation arrangements, relief may be given in the United Kingdom, or in the territory in relation to which the arrangements are made, in respect of any income or any chargeable gain, and
(b)condition A or B is met.
(2)Subsections (5) and (6) also apply if—
(a)under unilateral relief arrangements for a territory outside the United Kingdom, relief may be given in respect of any income or any chargeable gain, and
(b)condition A or B is met.
(3)Condition A is that it appears that the assessment—
(a)to income tax or corporation tax made in respect of the income, or
(b)to corporation tax or capital gains tax made in respect of the gain,
is not made in respect of the full amount of the income or gain.
(4)Condition B is that it appears that the assessment—
(a)to income tax or corporation tax made in respect of the income, or
(b)to corporation tax or capital gains tax made in respect of the gain,
is incorrect having regard to the credit, if any, to be given under the arrangements.
(5)Assessments may be made that are necessary to ensure—
(a)that the full amount of the income or gain is assessed, and
(b)that the proper credit, if any, is given.
(6)If the income is entrusted to any person in the United Kingdom for payment, an assessment under subsection (5) may be made on the recipient of the income.
(7)An officer of Revenue and Customs may make amendments—
(a)of assessments or determinations, or
(b)of decisions on claims,
that are necessary in consequence of Chapter 1 so far as it applies for petroleum revenue tax purposes.