5.—(1) Where a local authority is under an obligation by virtue of article 3 to make payment to Scottish Water for the billing year 2013-14, it must make the following instalment payments to Scottish Water—
(a)by the 14th day of each calendar month during the financial year 2013-14, 50 per cent of the amount that the local authority reasonably estimates that it would have to pay to Scottish Water by the application of the formula referred to in paragraph (2), were that formula applied at the end of that month, under deduction of any sums it has already paid to Scottish Water in respect of the relevant period;
(b)within 14 days from the end of each calendar month that falls within the financial year 2013-14, the amount calculated by reference to the formula referred to in paragraph (2), as applied at the end of that calendar month, under deduction of the sum already paid under paragraph (a);
(c)by the 14th day of each calendar month during the financial year 2014-15, 50 per cent of the amount that the local authority reasonably estimates that it would have to pay to Scottish Water by the application of the formula referred to in paragraph (3), were that formula applied at the end of that month, under deduction of any sums it has already paid to Scottish Water in respect of the relevant period; and
(d)within 14 days from the end of each calendar month that falls within the financial year 2014-15, the amount calculated by reference to the formula referred to in paragraph (3), as applied at the end of that calendar month, under deduction of the sum already paid under paragraph (c).
(2) The formula is that set out in article 3 except that—
(a)“A” is 99% of the total amount paid so far to the local authority as council tax or water services charges for the billing year 2013-14 by persons liable to pay that tax or those charges; and
(b)“(E x F)” is replaced by “(E x F)/12”.
(3) The formula is that set out in article 3 except that—
(a)“A” is the total amount paid so far to the local authority as council tax or water services charges for the billing year 2013-14 by persons liable to pay that tax or those charges; and
(b)“- (E x F)” is deleted.
(4) The estimated amounts referred to in paragraph (1)(a) and (c) must be estimated by reference to monthly billing and collection data.
(5) This article is subject to article 7.