Section 279C | Company with ring fence profits and other profits
From legislation.gov.uk
(1)This section applies if—
(a)a company is UK resident in an accounting period,
(ab)it is not a close investment-holding company in the period,
(b)its augmented profits of the accounting period—
(i)exceed the lower limit, but
(ii)do not exceed the upper limit, and
(c)its augmented profits of that period consist of both ring fence profits and other profits.
(2)The corporation tax charged on the company's taxable total profits of the accounting period is reduced by the total of—
(a)the sum equal to the ring fence marginal relief fraction of the ring fence amount, and
(b)the sum equal to the standard marginal relief fraction of the remaining amount.