96(1)The basic rule for calculating a writing-down allowance for an item of qualifying expenditure is—
where—
E is the amount of the qualifying expenditure;
C is the length of the part of the chargeable period falling within the writing-down period;
W is the length of the writing-down period.
(2)The basic rule is subject to the rules about—
(a)cessation of writing-down allowances (paragraph 97), and
(b)reduced writing-down allowances (paragraph 98).