The Double Taxation Convention between the UK and Portugal, which was signed in London on 15 September 2025, entered into force on 29 December 2025. The text of the Double Taxation Convention has been published as the Schedule to the Double Taxation Relief and International Tax Enforcement (Portuguese Republic) Order 2025 (Statutory Instrument 2025 No.1300), copies of which can be obtained from The Stationery Office. The text of the Order can also be accessed on the Internet at 2025 No. 1300

The provisions of the Double Taxation Convention will take effect in the UK from 1 January 2026 for taxes withheld at source, 6 April 2026 for income tax and capital gains tax and 1 April 2026 for Corporation tax; in Portugal from 1st January 2026 for taxes on income.