A development corporation's local contribution differential for a year of account is the amount by which their reckonable income for that year exceeds their reckonable income for the preceding year (and accordingly is nil or, as the case may be, a negative amount if their reckonable income for the year is the same as or less than that for the preceding year).
A determination shall state the assumptions on which it is based and the method of calculation used in it, and in making it the Secretary of State shall have regard, amongst other things, to past and expected movements in incomes, costs and prices.
A determination may be made for all development corporations or different determinations may be made for different corporations or groups of corporations.
Before making a determination for all development corporations the Secretary of State shall consult organisations appearing to him to be representative of development corporations.
A determination shall be made known to the corporations for which it is made in the year preceding the year of account for which it is to have effect.