Section 517C | Disposals of land: profits treated as trading profits
From legislation.gov.uk
(1)The profit or gain is to be treated for income tax purposes as profits of a trade carried on by the chargeable person.
(2)If the chargeable person is non-UK resident, that trade is the person's trade of dealing in or developing UK land (as defined in section 6B of ITTOIA 2005).
(3)But subsection (1) does not apply to a profit or gain so far as it would (apart from this section) be brought into account as income in calculating profits (of any person)—
(a)for income tax purposes, or
(b)for corporation tax purposes.
(4)The profits are treated as arising in the tax year in which the profit or gain is realised.
(5)This section applies in relation to gains which are capital in nature as it applies in relation to other gains.