4.—(1) Subject to paragraphs 5 to 7, where, in the case of an appropriate authority in England or Wales—
(a)X (being the total of the housing benefit amounts as calculated under Part II of Schedule 1, and the community charge benefit amounts calculated under this Part, in respect of that appropriate authority) exceeds Y (being 150 per cent. of the relevant amount), the community charge benefit additional sum for that appropriate authority for the relevant year shall be the amount as calculated under Part I of this Schedule less the excess; or
(b)X (being the total of the housing benefit amounts as calculated under Part II of Schedule 1 and the community charge benefit amounts calculated under this Part in respect of that appropriate authority) is less than Z (being 95 per cent. of the relevant amount) the community charge benefit additional sum for that appropriate authority shall be the amount as calculated under Part I of this Schedule plus the difference.
(2) The relevant amount for the purposes of paragraphs 4 and 6 is the aggregate of the housing benefit and community charge benefit applicable amounts and further amounts payable to that appropriate authority for the financial year ending 31st March 1991 calculated in accordance with Schedules 1 and 2 to the Housing Benefit and Community Charge Benefit (Subsidy) Order 1991(1) (calculation of subsidy in respect of administration costs).
S.I. 1991/587.