Section 22A | Trading allowance
From legislation.gov.uk
(1)The rules for calculating the profits of a trade, profession or vocation carried on by an individual are subject to Chapter 1 of Part 6A (trading allowance).
(2)That Chapter gives relief on relevant income and, where relief is given, disallows most deductions under this Part (see, in particular, sections 783AC, 783AF and 783AI).