Is the UK introducing an exit tax?

A business owner can spend twenty years building a company and find that most of their wealth is tied up in its shares. If they are weighing up a move, a headline about a UK exit tax sounds like a deadline. But the first question is what event would actually trigger the bill. Leaving the UK, selling shares while UK resident and returning after a short spell abroad are three different events. They already have different consequences, and a future departure tax would add another.

What did the October 2026 Budget actually announce?

The Budget of 28 October 2026 did not announce a general Capital Gains Tax charge triggered by an individual ceasing UK tax residence. HMRC’s Capital Gains Manual, updated after the Budget, also describes the absence of a general exit charge. An individual who keeps their shares when they move has normally made no sale at that point. The move alone does not generally make HMRC treat those shares as sold.

The Budget does use the phrase “exit charge” in relation to trusts. Certain trusts already face a Capital Gains Tax charge when they stop being UK resident. The government proposed an easement for qualifying trusts that become UK resident temporarily because a trustee moves, then cease UK residence within the specified period. That is a change to an existing trust rule. HMRC also describes existing migration charges for companies in certain circumstances. If you own the shares personally, the rules for a migrating company or trust are a separate question from the rules governing your own move.

The Budget measure more directly relevant to a founder selling shares is the proposed cut to Business Asset Disposal Relief, formerly Entrepreneurs’ Relief. The reduced rate is 18% on qualifying gains for disposals from 6 April 2026. The Finance Bill introduced on 4 November proposes cutting the lifetime limit on eligible gains from £1 million to £500,000 for disposals from 6 April 2027, with transitional provisions. The bill is still before Parliament as of 9 November. The limit is on the gain eligible for the reduced rate and takes account of previous claims. A £1 million purchase price is therefore a different figure from £1 million of qualifying gains.

What would a personal exit tax do?

One model is a deemed disposal on departure. Tax law would treat covered assets as sold at market value when the owner ceased UK tax residence, even if the owner kept them. The Centre for the Analysis of Taxation (CenTax) has proposed this approach alongside resetting the tax cost of assets to market value when people arrive. The idea is to tax growth during UK residence and, in the corresponding case of someone arriving, exclude growth that happened before they arrived. That is an independent policy proposal. Its design and estimates do not tell us what a government would enact.

Imagine a founder whose shares cost £100,000 and are worth £900,000 when they become non-resident. Under a hypothetical rule that treated those shares as sold at market value and used £100,000 as their tax cost, the starting gain would be £800,000. That is the gain before any exemptions, losses or reliefs, and no buyer has handed the founder £900,000. The example explains the mechanism. The UK has no general personal departure charge that would produce this calculation solely because the founder moved.

Now imagine the company loses a major customer and sells two years later for £600,000. Which valuation should drive the final bill? Would the rules allow an adjustment for the fall in value or let the founder wait to pay until there are sale proceeds? What if the new country computes the gain from the original £100,000 cost? These questions matter for an owner whose wealth is mostly in private shares. The answers would depend on the legislation and any relief available across borders.

Why does the idea keep coming up?

Supporters argue that if value grew while the owner lived in the UK, leaving before selling should not by itself take that growth out of the UK tax base. An arrival valuation paired with a departure valuation could make the rule work in both directions. For government, the aim would be to keep the right to tax gains built up during residence without having to depend on whether the person later comes back.

For founders, the hard part is paying or securing a bill on an asset that may take years to sell. A quoted share has a visible price. A stake in a private trading company can be harder to value, especially where there are restrictions on selling, different rights attached to different shares, or only an early expression of interest from a buyer. A policy that offers deferral could ease the cash problem, but valuation, reporting and possible tax in a second jurisdiction would still need to be worked out. Those details could matter more to an owner than the headline rate.

Which UK rules are relevant today?

• Capital Gains Tax on an actual disposal. If you sell shares while UK resident and the gain is within the UK charge, a later move does not undo that disposal. For a sale under contract, the date when the contract becomes unconditional can matter more than completion or payment. Business Asset Disposal Relief depends on eligibility, the date and your remaining lifetime limit.
• Temporary non-residence. If you become non-resident, sell assets you held before leaving and later resume UK residence, some gains can be charged in the period of return. The rules generally look at whether the relevant absence was five years or less and whether you were solely UK resident in all or part of at least four of the seven tax years before the departure year. Split years and treaty residence can affect how the period is worked out.
• Assets with a continuing UK tax connection. UK land and certain interests in companies that derive substantial value from UK land can remain within the UK tax net after departure. There are also rules for assets used in a UK trade carried on through a branch or agency. The asset and the person or entity that sells it matter.
• Inheritance Tax on a separate clock. The long-term UK residence rules can keep some overseas assets within the scope of UK Inheritance Tax for years after someone leaves, depending on their residence history. This is a separate exposure from Capital Gains Tax on selling shares and is assessed on its own terms.

What would make the next headline worth acting on?

Start with who has said what. A researcher publishing a model or a newspaper reporting that a measure is being considered gives you a reason to follow the issue. An announcement from HM Treasury gives you a policy to examine. A published bill gives you wording to test against your circumstances, including clauses that may change as Parliament considers it. Check the current status, the proposed date of effect and any transitional rules together. Budget measures can be drafted to take effect from a date earlier than Royal Assent, so the timetable matters even while a bill is in progress.

For a proposed departure charge, look for five details: who is in scope, which assets count, how the gain is valued, when payment falls due and what happens to people already part way through a move or sale. A proposal about founders with substantial private shareholdings could affect a very different group from a charge applying to a wide range of investments. An article that cannot point to published wording on those questions is describing possibilities.

There is still useful preparation to do under the current rules. Put together a dated ownership history, the terms of any likely deal and your record of homes, work and time spent in each place. If you are weighing up a move, ask a cross-border tax adviser to map the sale and residence dates under current law, then tell you which parts of the plan would need revisiting if a specific change were announced. That gives you something concrete to review when the next Budget comes around.