Section 19 of the Principal Act is amended in subsection (3)(aa) (inserted by the Finance Act, 1989) -
(a) by the insertion in subparagraph (ii)(II) after "remit to the Collector-General any amount of tax payable by him in respect of such taxable periods," of "and, in the case of an authorised person referred to in subparagraph (iv)(III) that amount shall be the balance of tax remaining to be paid, if any, after deducting from it, the amount of tax paid by him by direct debit in respect of his accounting period,", and
(b) in subparagraph (iv) by the insertion after clause (II) of the following:
"(III) without prejudice to the generality of the foregoing, require an authorised person to agree with the Collector-General a schedule of amounts of money which he undertakes to pay on dates specified by the Collector-General by monthly direct debit from his account with a financial institution and the total of the amounts specified in that schedule shall be that person's best estimate of