Britain does not have one. HMRC's Capital Gains Manual carries a page headed "no general exit charge", and it states that no legislation applies to all categories of person deeming the end of UK residence to be a disposal. A charge of around 20 per cent on unrealised gains in UK business assets was widely trailed before the Budget of 26 November 2025. It was not announced there, and nothing has been legislated since.
One open HMRC consultation sounds relevant and is not. "Modernising the distributions framework" concerns what counts as value taken out of a company by its shareholder. It says nothing about emigration, and reading it as the beginning of a departure tax is a mistake worth naming, because the phrase "business exits" appears in the commentary around it.
So Britain would be designing a new general individual exit charge rather than activating an existing one.
The hub article sets out why this instrument carries more of the migration argument than any other. What it could not do in four paragraphs is ask whether the thing holds up under detail. Four countries already run one, and they disagree with each other about almost everything except the principle.
Four countries, four different answers
They are not four versions of one design. Each picks a different thing to give away.
Canada treats most property as sold at market value on the day residence ends. The resulting tax can then be deferred until the asset is genuinely sold, for any amount and without interest, on an election filed by the April following departure. Above about 16,500 Canadian dollars of federal tax on the deemed disposal, security is required. The Canada Revenue Agency becomes a secured creditor and waits, possibly for decades.
Australia applies a deemed disposal at market value on ceasing residence, except for Australian land and similar assets. The taxpayer may instead elect out, keeping the assets inside the Australian net until they are next sold. The price of electing out is that value movement after departure counts too, so the choice is a bet on which way the asset goes. It is all assets or none.
Germany charges a deemed disposal of shares where someone holds at least 1 per cent of a corporation and has been fully liable to German tax for seven of the previous twelve years. It reaches a shareholding, not a portfolio.
Germany also runs a tail beside the charge. A qualifying German national who moves to a low-tax jurisdiction and retains substantial economic interests in Germany can stay inside an extended German liability for up to ten years, so the exit charge is not carrying the whole job by itself. Germany does not lean on a single instrument, which is worth noticing before Britain designs around one.
Norway refuses to wait. Since March 2024 the exit tax on latent share gains must be paid within twelve years whether or not anything has been sold, with a choice of paying at once, in instalments across the period, or in full at the end. A basic deduction of three million kroner applies, and 70 per cent of any dividend received in the meantime goes towards the outstanding claim.
Canada and Norway are the poles, and the liquidity objection the hub raises is answered generously by one and simply overridden by the other. A UK design has to choose between them, and the choice is a judgement about what the charge is for. Canada's answer lets payment wait until the gain becomes real. For Norway, an indefinite deferral is a loophole with a long fuse.
Valuation is the harder half
Liquidity gets the attention. Valuation is where the practical difficulty sits, and it is discussed far less.
A charge on unrealised gains needs a number for an asset nobody is buying. For listed shares that is a price. For a private company it is an argument, and the argument has to survive three things: a taxpayer with every reason to value low, a tax authority with no market to check against, and an appeal process that can run for years after the person has gone.
That is an inference rather than a finding. The claim rows behind this article do not establish how private-company valuations are made under these exit-charge regimes.
What the liability is worth once someone has left
A charge that cannot be collected is a charge in name only. Britain recovers tax abroad by two routes: the Council of Europe and OECD Convention on mutual administrative assistance, implemented here by statutory instrument and effective from 1 May 2008, and a double taxation agreement that carries recovery provisions of its own.
The Convention route exists, and what it carries has material limits.
Assistance under the Convention applies only to claims "which are not contested", and where the person is not resident in the country asking, only where the claim "may no longer be contested". The requested State is not obliged to act on a request made more than fifteen years after the instrument permitting enforcement. It may decline where the measures would be at variance with its own law or practice, where the country asking has not pursued all reasonable measures available at home - unless pursuing them would give rise to disproportionate difficulty - or where the administrative burden of helping is clearly disproportionate to what the country asking stands to gain.
Set that against the two problems above. A charge on private company shares can produce a disputed valuation of the kind this article has already described, and a disputed claim is the case the Convention holds at arm's length; whether a UK valuation appeal would make a claim contested within Article 11(2) is a question for a lawyer, not a finding here. Canada's deferral runs without a time limit and the recovery window does not, so a charge deferred for twenty years can fall outside the period in which another State owes any help at all.
Two things were not checked: which countries the Convention route reaches, and how many UK agreements carry recovery provisions.
The charge that acts before it exists
An exit charge announced is not yet an exit charge levied, and the announcement is the part that moves first. People with the option can leave before commencement, and people considering arrival can decline to start a clock they can see.
Britain already runs a smaller version of the same logic. The temporary non-residence rules reach back at someone who leaves and returns inside five years, which is a trailing instrument rather than an exit charge, and it produces the same incentive to time a move. That incentive exists, and our register holds no UK estimate of its behavioural effect.
The model and the regime are not the same thing
The study that documents a sharp departure response also models an exit charge and finds it curbs tax flight while raising output. The hub reports that in one sentence and this piece will not inflate it: the migration figures in that paper are measured, the exit-charge result is modelled, and no country has been observed running the policy it describes.
There is a second reason to keep them apart. The modelling is of a Norwegian exit charge, and Norway has since built one considerably harder than the version modelled. A twelve-year hard deadline with a dividend sweep is a different instrument from the one the paper tested. Its performance is not evidence about the model, and the model's result is not a forecast for the regime.
What Britain would have to pick
The hub's claim is that departure is a design variable. On this instrument the claim holds, and two parts of it are harder than the hub had room to say.
Liquidity has four worked answers and Britain could examine each of them. Valuation would still need to be specified for a UK regime. Enforcement has two routes, and the Convention route stops short of a contested claim. Anyone who tells you an exit charge is straightforward has skipped the middle of that list, and anyone who tells you it is impossible has skipped the first item.
Sources and evidence status
Canada Revenue Agency — Dispositions of property for emigrants of Canada (KB-093). Australian Taxation Office — How changing residency affects CGT (KB-094). Aussensteuergesetz section 6 (KB-095) and section 2 (KB-096). Skatteetaten — Exit tax (KB-097). HMRC Capital Gains Manual CG13400 and the Tax Update 2026 consultation collection (KB-064). HMRC helpsheet HS278 — Temporary non-residents and Capital Gains Tax (KB-098). HMRC Debt Management and Banking Manual DMBM560205 and DMBM560015 (KB-111). Council of Europe and OECD — Convention on Mutual Administrative Assistance in Tax Matters as amended by the 2010 Protocol, Articles 11, 14 and 21 (KB-112). 2001 UK/USA Double Taxation Convention as amended by the 2002 protocol, article list (KB-110). Blandhol, Curbing Tax Flight?, Princeton working paper (KB-055). All foreign-regime statements retrieved 14 August 2026; the collection sources 18 August 2026.
The exit-charge result in Blandhol is a modelled estimate, not an observed outcome, and is presented as one. The same paper's long-run output figure is contested and is not used here.
Valuation methodology and the size of announcement effects are not covered by any claim behind this article. Where the text reasons about them it says so. The collection position is now sourced, within limits stated in the text: the Convention's party list was not checked, nor was the number of UK agreements carrying recovery provisions, and the effect of a domestic valuation appeal on Article 11(2) is reasoning that needs legal review before anyone asserts it.
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