This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

International Manual

Employees of International Organisations: Treatment of pensions

The exemption from national tax accorded to the salaries and emoluments paid by international organisations does not normally extend to the pensions which those organisations pay to retired officials.

As a consequence, a pension payable by an international organisation to a former officer/official who is resident in the UK is taxable in accordance with the normal rules.  The one exception to this rule are pensions payable by the European Union (see INTM860820).