(1)The rules in subsection (3) apply to the calculation of the deduction by way of relevant corporation tax relief allowed in an accounting period—
(a)for the non-excluded element of the payment within section 835(1) or 836(1), or
(b)if there are two or more such payments, for the non-excluded elements of those payments.
(2)For the purposes of this section the non-excluded element of a payment is the element of the payment not excluded under section 843 (service charges etc).
(3)The rules are—
Rule 1 —meaning of amount E For any accounting period, amount E (which may be nil) is the expense or total expenses to be brought, in accordance with generally accepted accounting practice, into account in the period in respect of—
the non-excluded element of the payment, or
the non-excluded elements of the payments.
Rule 2 — calculations For every accounting period—
calculate the total of amount E for the period and amount E for every previous accounting period ending on or after the date of the transfer mentioned in section 835(1)(a) or 836(1)(a),
calculate the total of the deductions by way of relevant corporation tax relief for every previous accounting period ending on or after the date of that transfer, and
subtract the total at (b) from the total at (a) to give the cumulative unrelieved expenses for the period.
Rule 3 — meaning of post-spread period An accounting period is a post-spread period if for that accounting period, and every later accounting period, there are no payments within section 835(1) or 836(1).
Rule 4 — the deduction allowed in an accounting period If an accounting period is not a post-spread period, the deduction allowed for the period is equal to the cumulative unrelieved expenses for the period, but is equal to the commercial rent for the period if that is less (see section 844 or 845).
Rule 5 — accounting periods in which no deduction allowed If an accounting period is a post-spread period, no deduction is allowed for the period.