No charge at the border
Unlike some jurisdictions, the UK does not tax unrealised gains when an individual emigrates. There is no deemed sale of your portfolio, your company shares or your home on the day your residence ends. What actually happens is simpler: once you are non-resident under the Statutory Residence Test, usually from your departure date where split-year treatment applies, the UK stops taxing your worldwide income and gains and taxes only your remaining UK-source income. That is why a clean, well-documented exit matters more than any single form: the tests are mechanical and the date your residence ends drives everything else.
The five-year clawback is the closest thing to an exit tax
The temporary non-residence rules are where leavers actually get caught. If you were UK resident in at least 4 of the 7 tax years before you left, and your period of non-residence lasts 5 years or less, specific income and gains realised while you were away are treated as arising in the tax year you return and taxed then, at that year's rates. The list includes gains on assets you owned before leaving, dividends and distributions from close companies, certain pension payments and lump sums, and life-policy gains. To escape entirely you need to be non-resident for more than five years, which HMRC states means at least five years and one day, measured on Statutory Residence Test and split-year dates rather than calendar years. From 6 April 2026 the rules got wider for owner-managers: the old carve-out for dividends paid out of post-departure trade profits was removed, so for anyone returning on or after that date all close-company distributions taken while temporarily non-resident can be brought into UK income tax. For a founder who sat in a zero-tax jurisdiction, there may be no foreign tax to credit, so the UK charge on return can be the full liability.
What follows you anyway, and the company question
Two tails run regardless of the five-year test. First, UK residential and commercial property stays within UK Capital Gains Tax for non-residents, with a 60-day reporting and payment deadline after completion, even where nothing is due. Second, inheritance tax has been residence-based since 6 April 2025: if you were UK resident in at least 10 of the last 20 tax years you are a long-term UK resident, and that worldwide exposure only unwinds after a tail of between 3 and 10 years of non-residence under the residence-based IHT rules. Companies are a separate analysis again. A UK-incorporated company stays UK tax resident wherever its owner moves, so it cannot simply emigrate with you, and migrating a company's tax residence where that is possible can trigger a genuine corporation tax exit charge on unrealised gains; see our guide to running a UK company from abroad before assuming the company follows the shareholder. Horizon plans UK departures end to end, from the residence dates to the disposal and dividend timetable, so the five-year clock works for you rather than against you.