Breaking UK residence
Moving abroad does not switch off UK tax by itself. HMRC decides your status under the Statutory Residence Test, a set of day-count and ties tests, and until you fail them you remain UK resident on your worldwide income. For the year you leave, split-year treatment can divide the tax year into a UK part and an overseas part, so from departure the UK taxes only UK-source income; it is claimed on the SA109 pages of a Self Assessment return, not granted automatically. A P85 tells HMRC you have left and can prompt an in-year PAYE refund, but you should not file one if you are already sending a return for the year you leave.
What the UK keeps taxing
GOV.UK is clear that you usually pay tax on UK income even once you are non-resident. Rental profits stay chargeable, with the Non-Resident Landlord Scheme able to withhold tax unless HMRC approves gross payment, and a later sale of UK residential property must be reported, and any Non-Resident Capital Gains Tax paid, within 60 days of completion. Government service pensions, such as civil service or armed forces pensions, generally remain taxable only in the UK under the treaty.
What Portugal taxes
Portugal taxes its residents on worldwide income at progressive rates reaching 48%, with surcharges possible on top. The old NHR regime and its flat 10% pension rate are closed to new arrivals, and the replacement IFICI regime, a 20% rate on certain Portuguese-source professional income, excludes foreign pensions. Under the new treaty, in force since 29 December 2025 and effective for UK Income Tax from 6 April 2026, UK private and State pensions become taxable only in Portugal once you are resident there. Our guide to moving to Portugal from the UK covers the treaty, IFICI and the temporary non-residence trap in detail; confirm Portuguese specifics with a Portugal-qualified adviser.