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Expat Financial Planning: A UK Guide to Running Your Own Numbers
Moving abroad does not just change your address. It changes which tax authority has a claim on your income, what you are allowed to pay into, and — the part people notice last — whether you can still see your whole financial picture in one place.
This is a guide to expat financial planning for people who would rather understand the moving parts than hand them over. It covers what actually changes when you leave the UK, what stays the same, and what is worth doing in the six months either side of a move.
What expat financial planning actually involves
Search the phrase and you will mostly find wealth management firms. That is not an accident: cross-border finances are genuinely more complicated, and complexity is what advisers sell. But the complexity breaks down into five fairly ordinary questions.
Where am I tax resident, and does more than one country think it is them?
What can I still pay into — ISAs, pensions, workplace schemes — and what is now closed to me?
What happens to what I already hold in the UK?
What is all of it worth, in a currency I actually spend?
Does the plan still work if I stay abroad for five years? Fifteen? Permanently?
Four of those five you can answer yourself with good information. The fifth — what it is all worth, together, across currencies — is the one that is genuinely hard without a tool, and it is the one most people skip.
Your ISA stops taking new money the day you stop being UK resident
This is the rule that surprises people most. If you stop being a UK resident, you cannot pay new money into an ISA. Not a reduced amount. None.
What you do not lose is just as important: your existing ISAs stay open, and the money and investments already inside them keep their UK tax-free treatment. You are not forced to sell or transfer anything.
Two details worth knowing. There is an exception for Crown employees working overseas and their spouse or civil partner, who can keep subscribing. And you have to tell your ISA provider as soon as you stop being UK resident — that obligation sits with you, not with them.
It is also reversible. You can pay into your ISA again if you return and become UK resident, subject to the annual ISA allowance for that year. Source: HMRC guidance on ISAs if you move abroad.
Your UK pension keeps its tax relief — for five tax years
Pensions are more generous than ISAs here. After you leave, you remain what HMRC calls a relevant UK individual for the five tax years following the last tax year in which you were UK resident, provided you were UK resident when you joined the scheme.
During those five years you can keep getting UK tax relief on contributions of up to £3,600 gross a year — the basic amount. That is £2,880 out of your own pocket, topped up to £3,600. To get relief on more than that you need relevant UK earnings chargeable to UK income tax, which most people who have genuinely left will not have.
£3,600 is not a large number. But it is five years of contributions into a pot that keeps compounding while you are away, and it costs nothing to decide deliberately rather than by default. Source: HMRC Pensions Tax Manual PTM044100. If you want the underlying mechanics, we wrote about them in UK Pensions, Explained.
Residence is a test, not a feeling
Since 6 April 2013, UK tax residence has been decided by the Statutory Residence Test. It runs in a fixed order: the automatic overseas tests, which can make you non-resident outright; then the automatic UK tests, which can make you resident outright; and if neither settles it, the sufficient ties test, which weighs your UK connections against the number of days you spent here.
"I live in Lisbon now" is not a tax position.
Days counted, ties held, and the order the tests run in are what decide it — and the answer can differ from the one a friend with a similar-looking life received. HMRC's guidance note is RDR3.
Note also that residence is assessed by UK tax year — 6 April to 5 April — not calendar year. Moves that straddle early April need more care than moves in the middle of the year.
If you are moving to the UK, 2025 changed the picture
Most of this guide assumes you are leaving. If you are arriving, the biggest change in a generation has just happened. From 6 April 2025 the UK abolished the domicile-based remittance basis and replaced it with a residence-based system. Under the new foreign income and gains (FIG) regime, new arrivals who have been non-UK resident for the previous ten years pay no UK tax on foreign income and gains for their first four years of UK residence — at the cost of the personal allowance and the capital gains annual exempt amount.
Former remittance-basis users can also bring pre-6 April 2025 foreign income and gains into the UK through the Temporary Repatriation Facility, at a charge of 12% in 2025-26 and 2026-27, rising to 15% in 2027-28. The rates are set out in HMRC manual RDRM73400; the wider reform is covered in HMRC's technical note.
Inheritance tax moved onto a residence test too, and the detail matters more than the headline. You are a long-term UK resident — and so in scope for IHT on your worldwide estate — once you have been UK resident for at least 10 of the previous 20 tax years. After you leave, you stay in scope for a graduated period, not a flat ten years: three tax years if you were resident for 10 to 13 of the previous 20, then one additional year for each further year of residence, up to ten years for someone resident for all 20. Ten consecutive years of non-residence resets the test. The table is in HMRC manual IHTM47020.
Both the FIG regime and the Temporary Repatriation Facility are claimed on a Self Assessment return, which makes the registration deadline the one that actually binds. If you have not filed a UK return before, you must tell HMRC by 5 October following the end of the tax year — 5 October 2026 for 2025-26 — and file online by 31 January 2027. Source: HMRC Self Assessment deadlines.
The genuinely hard part: one number, several currencies
Here is the problem nobody sells you a product for. Salary in euros. Pension in sterling. A savings account in dollars left over from an earlier posting. A flat back home you have not decided what to do with.
Your net wealth is not the sum of those balances. It is the sum of those balances converted on the same day at the same rates.
And it moves when the rates move, even in a month where you did not spend or save a penny. If you have ever felt richer or poorer without being able to say why, this is usually it.
That is the calculation Moola does continuously rather than the once-a-quarter you would manage by hand. We wrote about why we built it that way in Built for life across borders, and about doing it in the language you think in in Money in your language.
What it costs to hand all this to someone else
Worth knowing before you decide. Which?, citing FCA data, puts the average UK initial advice charge at 2.4% of the amount invested and the average ongoing charge at 0.8% a year — rising to roughly 1.9% a year once the underlying product and portfolio charges are counted. Which? separately cites VouchedFor putting the average adviser hourly rate at £196 in 2023.
On a £250,000 portfolio, 1.9% is about £4,750 a year, every year. Cross-border advice typically sits at the higher end of the range, because it is harder. Source: Which? on how much financial advice costs.
None of which means do not hire anyone. A good cross-border adviser can earn several years of fees on one well-timed decision, and there are situations — a large pension transfer, a complex estate, two tax authorities disagreeing — where you want a professional on the hook. The point is to know the number before you decide, and to be clear about which questions genuinely need paying for.
What Moola does not do
Since this article is partly about not overpaying for things, it would be poor form not to be equally clear about our own limits.
We do not file anything. Moola does not submit a return, does not talk to HMRC on your behalf, and is not an agent.
Our tax calculations are UK rules. If you are tax resident somewhere else, treat the tax lines as indicative — the balances, the currency conversion and the long-run projection are the parts doing real work for you.
We are not regulated advice. Moola will show you what your numbers do under a set of assumptions. It will not tell you to buy a product, and it cannot take a view on whether a transfer out of a UK scheme is right for you.
We do not guess at residence. Your residence position is an input you give us, not something we infer from a phone's location.
If what you need is someone on the hook for a judgement call with six figures riding on it, that is an adviser, not an app. If what you need is to stop losing track of what you own across four countries, that is this.
A checklist for the six months around a move
Tell your ISA provider as soon as you stop being UK resident. This is your obligation.
Work out your residence position against RDR3 for the tax year, not the calendar year.
Check whether a double taxation agreement covers each type of income you will have.
Decide deliberately whether you will use the five years of £3,600 pension relief, rather than letting it lapse by default.
If you are arriving and will need to file, register for Self Assessment by 5 October following the end of your first UK tax year.
Update the correspondence address on every UK account — several providers restrict what they will do for a non-UK address.
Check whether your UK investment platform will keep you as a client once you are abroad. A number will not, and finding out after you land is worse than finding out before.
Record what you hold and where, in one place, before the move scrambles the paperwork.
Pick the currency you actually spend in, and start tracking net wealth in it from day one.
Common questions
Can I keep my ISA if I move abroad?
Yes. Your existing ISAs stay open and keep their UK tax-free status. What you cannot do is pay new money in, unless you are a Crown employee working overseas or their spouse or civil partner.
Can I pay into a UK pension from abroad?
Yes, with limits. You can get UK tax relief on up to £3,600 gross a year for the five tax years after the last tax year in which you were UK resident, if you were UK resident when you joined the scheme. Relief above that requires relevant UK earnings chargeable to UK income tax.
Do I still pay UK tax if I live abroad?
It depends on your residence status under the Statutory Residence Test and on the source of the income. Some UK-source income — rent from a UK property, for example — can remain taxable in the UK even when you are non-resident. A double taxation agreement between the UK and your new country usually determines which of them taxes what.
How long does UK inheritance tax follow me after I leave?
Between three and ten tax years, depending on how long you were UK resident before you left. Three years if you were resident for 10 to 13 of the previous 20 tax years, rising by a year for each additional year of residence, to a maximum of ten. It is not a flat ten-year tail, which is how it is often summarised.
Do I need a financial adviser to move abroad?
No. The rules that matter most — ISA subscriptions, pension relief, residence — are published by HMRC and readable in an afternoon. Advice earns its fee on judgement calls and on situations with real money at stake, not on looking up rules.
How many British people live abroad?
The UN estimates at least 4.8 million people born in Britain were living overseas in 2024, with Australia the largest destination at around 1.1 million. The estimate excludes more than 70 countries and counts only the British-born, so the true figure is higher. Source: ONS, UK emigration explained, May 2026.
Seeing it all in one place
Moola is a financial planning app built in the UK for people whose money does not sit neatly in one country. It tracks net wealth across currencies, models what-ifs — a move, a career break, a currency shift — and answers questions over WhatsApp rather than making you log into a dashboard you will forget about.
This article is general information about UK rules, not personal financial, tax or legal advice. Rules change and your position depends on your own circumstances. Check current HMRC guidance, or speak to a qualified adviser, before acting on anything here.
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