A development corporation's housing costs differential for a year of account is the amount by which their reckonable expenditure for that year exceeds their reckonable expenditure for the preceding year (and accordingly is nil or, as the case may be, a negative amount if the reckonable expenditure for the year is the same as or less than that for the preceding year).
A development corporation's reckonable expenditure for a year is the aggregate of—
A determination may be made for all development corporations or different determinations may be made for individual corporations; and a determination may be varied or revoked in relation to all or any of the corporations for which it was made.
Before making a determination for all development corporations the Secretary of State shall consult organisations appearing to him to be representative of development corporations.