66Special rules for fresh income
(1)Income tax under Case III, IV or V of Schedule D shall, in the following cases, be computed on the following amounts, and, where the tax is charged under Case III, paid on those actual amounts without any deduction—
(a)as respects the year of assessment in which the income first arises, on the full amount of the income arising within that year;
(b)where the income first arose on some day in the year preceding the year of assessment other than 6th April, on the amount of the income of the year of assessment; and
(c)where the income first arose on 6th April in the year preceding the year of assessment, or on some day in the year next before the year preceding the year of assessment other than 6th April, and the person charged so requires by notice given to the inspector at any time within six years after the end of the year of assessment, on the amount of the income of that year.
(2)Where subsection (1)(c) above applies, and income tax charged otherwise than in accordance with that provision has been paid, any amount overpaid shall be repaid.
(3)If at any time a person acquires a new source of any income in respect of which he is chargeable under Case III, IV or V of Schedule D, or an addition to any source of any such income, then, for the year of assessment in which income first arises from the source or addition and the two following years of assessment, income tax in respect of the income from the source or addition shall, notwithstanding section 73, be computed separately and subsection (1) above shall apply.
(4)For the purposes of the charge under Case III, if at any time interest on a debt ceases to be payable subject to deduction of income tax, subsection (3) above shall apply as if the debt were a new source of income acquired by the creditor at that time.
(5)Where income arising to any person from any security or possession in any place out of the United Kingdom ceases at any time to be chargeable to income tax by deduction under the provisions of section 123, subsection (3) above shall apply as if that security or possession were a new source of income acquired by that person at that time.
(6)In any case where tax is to be charged under Case IV or V by reference to the amount of income received in the United Kingdom, references in this section to income which arises or arose shall have effect as references to income which is or was so received.