(1)This section applies if a proportion of the income arising to the trustees in the current tax year is untaxed income.
(2)A proportion of the allowable expenses is excluded for the purposes of section 486.
(3)That proportion is the same as the proportion of the income arising to the trustees which is untaxed income.
(4)For the purposes of this section the income arising to the trustees is untaxed income so far as they are not liable to income tax on it wholly or partly because they—
(a)have been non-UK resident, or
(b)have been treated as resident in a territory outside the United Kingdom under double taxation arrangements.
(5)If the income tax charged on the income arising to the trustees is limited under Chapter 1 of Part 14 (limits on liability to income tax of non-UK residents), the untaxed income includes so much of the income so arising which is disregarded income (within the meaning of that Chapter) except so far as the disregarded income is within subsection (6).
(6)The disregarded income is within this subsection so far as—
(a)sums representing income tax have been deducted from the income,
(b)sums representing income tax have been treated as deducted from or paid in respect of the income, or
(c)there are tax credits in respect of the income.