PIM2080 - Deductions: main types of expense: criminal payments, bribes and similar items
A deduction cannot be claimed for payments that are:
criminal in themselves - for example, a bribe to secure a contract; or
made in response to a blackmail threat.
This is made clear in section 55 of the Income Tax (Trading and Other Income) Act 2005 (applied to property businesses by section 272 and 272ZA) and section 1304 of the Corporation Tax Act 2009.