“(1) Subject to subsection (2) below, the difference between— (a) the amount of income tax and capital gains tax contained in a person's self-assessment under section 9 of this Act for any year of assessment, and (b) the aggregate of any payments on account made by him in respect of that year (whether under section 59A of this Act or otherwise) and any income tax which in respect of that year has been deducted at source, shall be payable by him or (as the case may be) repayable to him as mentioned in subsection (3) or (4) below (3) In a case where the person— (a) gave the notice required by section 7 of this Act within six months from the end of the year of assessment, but (b) was not given notice under section 8 … of this Act until after the 31st October next following that year, the difference shall be payable or repayable at the end of the period of three months beginning with the day on which the notice under section 8 … was given. (4) In any other case, the difference shall be payable or repayable on or before the 31st January next following the year of assessment.”