4.—(1) The levy on an employer is assessed in accordance with this article.
(2) The Board must assess the levy separately in respect of each construction establishment of an employer, but in agreement with the employer one assessment may be made in respect of any number of such establishments, in which case those establishments are to be treated for the purposes of that assessment as constituting one establishment.
(3) Subject to the exemptions in article 5 the amount to be assessed by way of levy in respect of a construction establishment is A + B - C (and if A + B is less than C no levy shall be assessed) where—
A is an amount (rounded down where necessary to the nearest £1) equal to 0.5 per cent of the aggregate of the emoluments and payments intended to be disbursed as emoluments which have been paid or are payable by the employer to or in respect of persons employed by the employer in the base period;
B is the sum which (rounded down where necessary to the nearest £1) represents 1.5 per cent of all payments (other than payments which are not in respect of the provision of services) made to any persons during the base period under labour-only agreements in respect of work carried out at or from the establishment; and
C is the sum which (rounded down where necessary to the nearest £1) represents 1.5 per cent of all payments (other than payments which are not in respect of the provision of services) received by the employer during the base period from any other employers in the construction industry under labour-only agreements in respect of work carried out at or from the establishment.
(4) For the purposes of paragraph (3)—
(a)a person employed wholly in the supply of food or drink for immediate consumption or in agriculture is to be left out of account;
(b)a person who was normally working for an aggregate of less than 8 hours weekly is to be left out of account; and
(c)a company director remunerated solely by fees shall be left out of account, but otherwise a company director (including a person occupying a position of director by whatever title he is called) is to be treated as employed.