Register with HMRC and file Self Assessment (or Corporation Tax return)
Enforced by: HMRC
Taxes Management Act 1970
Applies to any UK trading activity connected with the body that is not covered by diplomatic or organisational immunity — for example a locally-registered support or liaison entity. The core diplomatic/organisational functions themselves are outside ordinary tax registration under the Diplomatic Privileges Act 1964 and International Organisations Act 1968.