Leaving the UK: CGT Planning on Departure

Many of you have been quietly running the numbers. A portfolio built over twenty years, a business you are thinking about selling, a couple of buy-to-lets that have done well. You are planning to leave the UK, and somewhere in that process the question of leaving UK capital gains tax comes up: what does HMRC actually take, and does it matter whether you sell before you leave or after?

It matters quite a bit.

What you own, when you sell it, and how long you stay away are the three variables that determine your exposure. Get them right and you protect a substantial portion of your gains. Sell at the wrong moment, or come back before five full tax years have passed, and you can find yourself paying tax on gains you were convinced you had left behind.

No exotic structures required. Just a calendar and a clear understanding of the rules. Let's take a look at each one.

UK CGT rates on departure: residential vs non-residential assets

First, the basics, because the rates drive everything else. The UK taxes capital gains at different rates depending on what you sold and which income tax band the gain sits in once stacked on top of your income.

For disposals in the current tax year, the headline rates work like this:

• Non-residential assets (shares, funds, business interests, crypto): 18% for gains falling in the basic rate band, 24% for gains in the higher rate band.
• Residential property: also 18% and 24%, after the alignment that took the old 28% top rate down.
• Annual exempt amount: a modest £3,000, a long way down from the £12,300 it once was, so most meaningful gains are taxable from the first pound above that.
• Business Asset Disposal Relief (BADR): 14% on qualifying business disposals up to the £1 million lifetime limit, rising again under the announced schedule, so the timing of a business sale matters as much as the timing of your move.

One detail that trips people up: the gain stacks on top of your income to decide which band it falls in. So a year where you have already drawn a large salary or taken a dividend can push an otherwise modest gain straight into the 24% band, while the same gain in a low-income year might sit partly in the basic rate band at 18%. The year you choose to sell is itself a planning lever, quite apart from the question of residence.

The key is that these rates apply while you are UK resident. The entire point of departure planning is to get yourself into a tax year where you are non-resident before you trigger the gain, so that the gain falls outside the UK net altogether. Whether that works cleanly depends on the two rules we are about to cover: split-year treatment and the temporary non-residence rule. Before any of this, you need to know whether you are even leaving for tax purposes, which is governed by the day-counting and tie tests we cover in detail in our guide to the UK Statutory Residence Test.

UK split year treatment: the 8 cases and which one you qualify for

Here is the first thing most people get wrong. UK tax residence is normally an all-or-nothing affair for a whole tax year. You are either resident for the entire year (6 April to 5 April) or you are not. That creates an obvious problem if you leave in, say, September. Are you really going to be taxed as a UK resident on worldwide gains for the six months after you have already gone?

This is where UK split year treatment comes in. It carves the tax year into a UK part and an overseas part, so that for the overseas part you are effectively treated as non-resident. In other words, you do not get clobbered on foreign income and gains arising after you genuinely left.

But (and this matters) you do not get to choose split-year treatment. You either fall into one of the statutory cases or you do not. There are eight cases in total, three of which apply to people leaving the UK:

• Case 1: Starting full-time work overseas. You take up full-time employment abroad, meet the sufficient hours test, and keep your UK days below the limit. The split happens around your start date overseas.
• Case 2: The partner of someone covered by Case 1. You join a spouse or partner who has gone abroad for full-time work, and you move to live with them.
• Case 3: Ceasing to have a UK home. You no longer have any home in the UK, you spend fewer than 16 days here afterwards, and within six months you become tax resident in another country (or are present in it at the end of each day for six months).

The other five cases (4 through 8) deal with people arriving in the UK, which is a different article entirely. For a departing taxpayer, your planning revolves around which of Cases 1, 2, or 3 you can satisfy, because each one fixes a different split date and therefore a different cut-off for when your gains become safely non-resident.

Now I know what you're thinking. Why does the exact split date matter so much? Because a gain you trigger one day before the split is fully UK-taxable, and the same gain one day after may not be. Let's go back to an example.

Let's say John from Bristol sells his consultancy and accepts a full-time role in Dubai starting 1 October. He clears out of his UK home, his family follows in November. John potentially qualifies under Case 1 (full-time work overseas) or Case 3 (no UK home). If his split date is set at the start of his overseas work, any portfolio he sells from October onwards falls in the overseas part of the year. Sell in September instead and that same gain is taxed at up to 24%. Same asset, same buyer, very different result. The mechanics of a UK-to-Gulf move are covered in more depth in our piece on moving from the UK to Dubai.

A point worth labouring, because it catches careful people too: the cases are not a menu you pick from for the best answer. HMRC applies a priority order where more than one case could apply, and the case that wins can set an earlier or later split date than the one you were hoping for. John might prefer the Case 1 date but find the facts point to Case 3, or vice versa. Map this out before you sell anything, not after, because by the time you have a contract note in hand the split date is already fixed by what you actually did.

The temporary non-residence rule: the 5-year boomerang trap

Now for the rule that catches people who think they have already won. You have qualified for split-year treatment, gone abroad, sold your assets while non-resident, paid no UK CGT. Job done. Then eighteen months later you get homesick, or the job ends, or the relationship that took you abroad does not work out, and you move back to Britain.

Welcome to the UK temporary non-residence rule. If you return to UK residence within roughly five years of leaving (the precise test counts tax years of non-residence), HMRC can reach back and tax gains you realised while you were away as if they arose in the year you return. The gain does not vanish because you were non-resident. It is parked, and it boomerangs back the moment you re-establish residence inside the window.

The rule bites on assets you owned before you left and then sold during your absence. A few things to keep straight:

• The window is about five years. You generally need a period of non-residence spanning more than five years to be safe from the clawback. Four years and a change of heart is not enough.
• It targets pre-owned assets. Gains on assets you both acquired and disposed of while abroad are typically outside the charge. It is the latent gain on what you already held that comes home with you.
• Income gets caught too. Certain distributions, closely-held company dividends, and pension lump sums taken during the gap can also be pulled back into charge on return.

The reason the rule exists is not hard to see. Without it, anyone could step out for a single non-resident tax year, sell a lifetime of accrued gains free of UK tax, and stroll back through Heathrow the following April. The five-year clock is HMRC's way of making sure your departure is real rather than a one-year tax holiday timed around a disposal.

So what does all of this mean for you? It means the decision to leave is not really complete until you have committed to staying gone long enough. If there is any realistic chance you bounce back within five years, the "tax-free" gain you crystallised abroad is a contingent liability, not a saving. Plan your exit on the assumption that you might have to defend the full five-year clock.

UK non-resident CGT on UK property since April 2019

Here is the part people most commonly misunderstand. Becoming non-resident does not give you a free pass on UK land and buildings. Since April 2019, the UK non-resident CGT regime extends to all disposals of UK property by non-residents, both residential and commercial, and even to disposals of shares in "property-rich" companies (broadly, entities deriving 75% or more of their value from UK real estate).

Before 2015 a non-resident could often sell UK property with no UK CGT at all. That door is now firmly shut. The rules tightened in stages, and the current position is straightforward to state, if not to love:

• All UK real estate is in scope. Residential since 2015, commercial and indirect disposals since April 2019. Your London flat does not escape just because you now live in Lisbon.
• Only the gain since the rebasing date is taxed (usually). For residential property you can typically rebase to the April 2015 value, and for commercial to April 2019, so it is generally the growth since then that is charged, not the whole historic gain.
• A 60-day reporting and payment deadline applies. You must file a non-resident CGT return and pay within 60 days of completion, regardless of whether you are inside Self Assessment. Miss it and penalties stack quickly.

The practical upshot is that the asset class people most want to hold onto, UK property, is precisely the one that follows them abroad. If your wealth is heavily weighted to British bricks and mortar, leaving the UK does far less for your CGT exposure than leaving with a portfolio of liquid global equities. This is a major reason that where you go next, and the tax regime you land in, matters so much. Low or zero capital-gains jurisdictions such as the territorial systems we describe in our guides to Paraguay tax residency and Panama residency and tax can change the calculus on everything except the UK property that stays behind.

Pension access: timing withdrawals around departure

Pensions are where good departure plans quietly fall apart, because the temporary non-residence rule reaches into them too. If you take a large pension lump sum while non-resident and then return inside the five-year window, that lump sum can be dragged back into UK charge.

A few practical points to weigh:

• Tax-free lump sums are not always tax-free abroad. The UK may treat your 25% pension commencement lump sum as tax-free, but your new country of residence may not recognise that treatment at all and may tax the whole withdrawal.
• Treaty position governs ongoing pension income. Whether the UK or your new home taxes your regular pension drawdown depends on the relevant double tax treaty. Some treaties give exclusive taxing rights to the country of residence, others do not.
• Timing the crystallisation matters. Drawing benefits in a year where you are cleanly non-resident, and intending to stay so beyond five years, is very different from drawing them in a transitional year or shortly before a possible return.

The key is that pension decisions and your residence timeline have to be planned together, not in separate boxes. Crystallising a large benefit in the wrong tax year can undo the entire saving from your CGT planning.

ISAs, EIS, and SEIS: what happens when you leave

Now let's take a look at the tax-advantaged wrappers that so many UK residents have built up, because they behave very differently once you cross the border.

• ISAs: Your existing ISA stays open and the investments inside it continue to grow free of UK tax, but you cannot pay new money in for any tax year in which you are non-resident. The bigger problem is your new country, which almost certainly does not recognise the ISA wrapper and will tax the income and gains inside it under its own rules. The UK shelter becomes irrelevant the moment another tax authority looks through it.
• EIS (Enterprise Investment Scheme): Income tax relief you already claimed can be clawed back if you dispose of the shares, or in some cases if you become non-resident, within the three-year holding period. The CGT deferral relief that many use to roll a gain into an EIS investment can also crystallise on an early departure.
• SEIS (Seed Enterprise Investment Scheme): Same broad logic, with its own three-year clock. Leave before the relevant period is up and reliefs you banked can be reversed, turning a tax-efficient investment into an ordinary, and now taxable, one.

There is a wider trap hiding under all three wrappers. The country you move to gets to decide how it treats them, and most of them treat an ISA or an EIS holding as a plain investment account with no special status at all. Some will tax the gains inside it annually, some on disposal, and a few operate wealth taxes that catch the balance regardless of whether you sell. The shelter you spent years building is only as good as the recognition it gets at your destination, which is usually none.

Check the holding-period clock on every relief-bearing investment before you set a departure date. A move that lands you six months short of a three-year EIS period can cost you the relief on the entire holding, which is rarely a price worth paying for leaving a few months earlier.

National Insurance: continuing contributions from abroad

This one is less about avoiding tax and more about not quietly damaging your future. When you leave the UK you generally stop paying Class 1 National Insurance, and your contribution record stops building. That record is what funds your eventual UK State Pension, and you typically need 35 qualifying years for the full amount and at least 10 to get anything at all.

If you leave with, say, 22 years on the clock, doing nothing means your State Pension is permanently reduced. The fix is usually voluntary contributions:

• Class 2 (cheaper): Available to many people who were employed or self-employed in the UK immediately before leaving and who work abroad. The weekly cost is low, which makes the return on each year of contribution genuinely attractive.
• Class 3 (more expensive): The fallback for those who do not qualify for Class 2, letting you fill gaps in your record at a higher cost per year.
• The eligibility check matters: Whether you can pay Class 2 rather than Class 3 depends on your work history and your situation abroad, so confirm it with HMRC before assuming the cheaper rate.

For many departing clients, voluntary Class 2 contributions are one of the highest-return decisions in the entire move, and one of the most overlooked.

The departure checklist: HMRC notifications and timing

So let's pull the timing together into the practical sequence. Departure planning is mostly about doing the right things in the right order, and the order is not negotiable if you want the result to hold up.

1. Confirm your residence position first. Run the Statutory Residence Test for the year of departure and the years after, and identify which split-year case (1, 2, or 3) you will rely on. Everything downstream depends on this.
2. Sequence your disposals around the split date. Where possible, trigger major gains in the overseas part of the year or in a clean non-resident year, not in the weeks before you leave.
3. Stress-test the five-year window. Decide honestly whether you can commit to more than five tax years of non-residence. If not, treat gains realised abroad as still at risk under the temporary non-residence rule.
4. Notify HMRC. File the appropriate form (commonly the P85, or through your Self Assessment return) to report that you have left, and continue filing returns where you still have UK-source income or UK property.
5. Diarise the 60-day clock for any UK property. Every disposal of UK land while non-resident needs a return and payment within 60 days, full stop.
6. Sort National Insurance and pensions. Apply for voluntary contributions if it makes sense, and align any pension crystallisation with your residence timeline rather than treating it as a separate decision.
7. Get advice that spans both countries. UK-side planning is only half the picture, because the regime you land in decides what happens to the income and gains the UK lets go.

As you can see, leaving the UK cleanly is far more about calendar discipline than clever structuring, and the abolition of the old non-dom regime has only sharpened the incentive for many to plan a proper exit, as we cover in our analysis of the UK non-dom abolition. If you want this sequenced properly for your own assets and destination, this is exactly the kind of cross-border exit our advisory team builds for clients every week.