3.—(1) The amount which is the total of—
(a)25 per cent. of the difference between the amount calculated in accordance with paragraph 2 above and the amount which would be so calculated if, in respect of any relevant day or any day in a preceding year, any determination by the authority under section 47(1)(a) of the Act as regards a hereditament in relation to which the condition in section 47(2)(a) applies were taken into account;
(b)75 per cent. of the difference between the amount calculated in accordance with paragraph 2 above and the amount which would be so calculated if, in respect of any relevant day or any day in a preceding year, any determination by the authority under section 47(1)(a) of the Act as regards a hereditament other than a hereditament in relation to which the condition in section 47(2)(a) applies were taken into account; and
(c)75 per cent. of the difference between the amount calculated in accordance with paragraph 2 above and the amount which would be so calculated if, in respect of any relevant day or any day in a preceding year, any reduction or remission by the authority under section 49 of the Act were taken into account;
less the amount calculated under sub-paragraph (2) below.
(2) The total of any reduction in a chargeable amount by virtue of a determination under section 47(1)(a) of the Act and any reduction or remission under section 49 of the Act which has been taken into account in a calculation for a preceding year but which—
(a)on the basis of the information before the person making the relevant calculation, should not have been so taken into account; and
(b)has not been taken into account for the purposes of this sub-paragraph in a calculation for a preceding year;
multiplied by the relevant percentage.
(3) In sub-paragraph (2) above, “the relevant percentage” means, in the case of a reduction in a chargeable amount by virtue of a determination under section 47(1)(a) of the Act as regards a hereditament in relation to which the condition in section 47(2)(a) applies, 25 per cent., and in the case of any other reduction or the remission of a chargeable amount, 75 per cent..