Moving abroad is one of the most significant financial events in a person's life. The tax system changes, the investment options change, the insurance requirements change, and — in a fundamental sense — the financial planning framework that applied in the UK no longer applies in the same way.
Yet most expats, in the chaos of relocation, carry forward their UK financial life intact. The result is a series of predictable, avoidable and often costly mistakes. Here are the ten we encounter most frequently.
1. Thinking the ISA retains its tax-free status abroad
The Individual Savings Account (ISA) is one of the best tax shelters available to UK residents. But "UK residents" is the critical phrase.
Once you become non-UK-resident, an existing ISA does not automatically become taxable — you can retain it, and the UK will not tax the income or gains within it. The problem is two-fold:
- You cannot make new contributions to a UK ISA once you are non-UK-resident (subject to certain exceptions, including for Crown employees serving overseas)
- Your country of residence may not recognise the ISA's tax-free status — and will tax the income and gains within it as if they were in any other account
In many countries (including the USA, Germany, Spain and others), a UK ISA is treated as a foreign investment account, fully taxable on income and gains. Continuing to treat it as tax-free on your foreign tax return is a compliance error.
What to do: Check the tax treatment of your ISA in your country of residence, report it correctly on your local tax return, and consider whether to retain it or close it.
2. Not updating wills after a move
A UK will is governed by English law and covers UK assets. It may be effective for UK-situs assets — but it almost certainly does not work seamlessly for overseas assets.
If you own property in Spain, France or Cyprus, the local succession laws apply to that property — and in civil law countries, forced heirship rules may override the terms of your will in any event. EU Succession Regulation 650/2012 allows EU-resident individuals to choose for the law of their nationality to govern their succession — but you must make that election explicitly in your will.
What to do: Review your will as soon as you become a long-term resident in any new country. In most cases, a specialist cross-border estate planner should advise on whether you need a will in each jurisdiction where assets are held.
3. Ignoring the pension contribution gap
Many expats stop contributing to any pension when they leave the UK. This is rational if the only alternative is a UK-registered pension with limited flexibility for overseas residents — but it ignores the broader picture.
UK SIPP contributions can still be made by non-residents (up to the "relevant UK earnings" threshold, with a minimum of £3,600 gross per year in any case, regardless of earnings). Many international employers offer pension arrangements. And some countries — Cyprus, for example — have favourable lump-sum pension tax treatment that makes continued pension accumulation attractive.
What to do: Take stock of all pension provision — UK and overseas — within the first year of moving abroad. Model the retirement gap and make a deliberate decision about contributions, rather than drifting into under-provision.
4. Failing to establish clear tax residency
"Tax residency" is not automatic — it is determined by tests that differ in each country, and it is possible (inadvertently) to be tax-resident in two countries simultaneously or to fall between two stools.
UK tax residency is determined by the Statutory Residence Test (SRT). The SRT has complex tie-counting rules: maintaining a UK home, having a UK-resident spouse, working significantly in the UK, and spending more than a de minimis number of days in the UK all contribute ties that can result in UK residence.
Expats who leave but maintain a UK property, visit frequently, and maintain family in the UK are often surprised to find that they have remained UK-resident for tax purposes — or have become resident in two countries with no tax treaty relief.
What to do: Model your UK residence status under the SRT before you leave. Plan the number of UK days carefully. If the picture is complex, get a formal SRT analysis.
5. Not planning before the move — timing of disposals matters
Capital gains arising on assets held before departure can often be managed with better timing. In the UK, the CGT annual exempt amount can be used in the final UK-resident year. In some countries, a step-up in base cost is available on arrival — meaning any accrued gain "resets" on your first day of residence.
Many expats realise — after arriving in their new country — that they sold a property or investment fund in the wrong tax year, generating a large gain in the new jurisdiction that would have been better crystallised in the old one.
What to do: Before leaving, review the unrealised gains in your portfolio, your property, and any business interests. Model whether it makes more sense to crystallise those gains before departure, after departure, or over time.
6. Continuing UK National Insurance voluntarily when an overseas equivalent exists
Class 2 or Class 3 National Insurance voluntary contributions can be an excellent investment — as discussed elsewhere in our guides. But for some expats, the country they move to has its own social security system that provides equivalent (or superior) benefits, and contributions are compulsory as part of employment or self-employment in that country.
Paying both UK voluntary NI and a foreign social security levy is often unnecessary — many countries have social security reciprocity agreements with the UK that allow payment in one system only. Check whether your country of employment has a reciprocal social security arrangement with the UK.
7. Keeping a UK residential mortgage on a property when abroad
Many UK lenders' mortgage terms require the borrower to notify the lender if they cease to occupy the property as their main residence. Failing to notify — and continuing to occupy the property as a buy-to-let while on a residential mortgage rate — is technically a breach of mortgage terms and potentially mortgage fraud.
Separately, buy-to-let mortgage rates are often higher than residential rates; lenders may require you to switch on notification of non-occupation.
What to do: Notify your UK mortgage lender if you are letting a UK property. Ensure you have appropriate buy-to-let or consent-to-let permissions.
8. Not using double taxation treaties
The UK has double taxation treaties with over 130 countries. These treaties can significantly reduce tax withholding on UK-source income (dividends, interest, pensions) paid to non-UK-resident individuals, and provide relief mechanisms for foreign income.
Many expats simply pay UK withholding tax at the standard rate because they have not claimed treaty relief. For pension income, dividends from UK companies, and UK rental income, the applicable treaty rate may be lower than the domestic UK rate.
What to do: Identify which double taxation treaty applies between the UK and your country of residence. Claim treaty relief at source where possible, or claim it via self-assessment.
9. Underinsuring — especially life cover
Life cover bought in the UK may not pay out if you are living abroad. Many UK term assurance policies contain residency conditions — the policy may lapse, be voided, or not pay out if the insured is resident in certain countries.
Health insurance is the most obvious gap — UK expats lose access to the NHS the moment they establish residence abroad (though short visits to the UK are covered for emergency treatment). But life cover, income protection and critical illness cover are also frequently inadequate for expats.
What to do: Review all insurance policies on moving abroad. Check residency conditions. Obtain specialist international health insurance and review life cover with an adviser experienced in international coverage.
10. Using UK-only financial products abroad
UK-specific financial products — NS&I savings, Help to Buy ISA, Lifetime ISA, and others — are for UK residents. Once you become non-resident, contributions are prohibited and continued holding may be non-compliant.
More broadly, UK tax-wrapped products (ISAs, SIPPs) are designed for a UK tax environment. Once you are in a different tax jurisdiction, you need products designed for your new situation — an offshore bond, an internationally portable pension, a multi-currency investment account. Continuing to use UK-centric products because they are familiar, without considering whether they are appropriate for your new tax status, is a common and costly oversight.
How Global Investments can help
We specialise in the financial planning needs of internationally mobile individuals. Whether you are planning a move, already abroad, or returning to the UK, we can review your position and help you avoid the mistakes described here.
Contact us for an initial consultation.
This article is for general guidance. Tax rules, product terms and regulations change frequently and vary by country. Always obtain independent professional advice.
This article is for general information only and does not constitute financial, legal or tax advice. Rules, prices and regulations change; verify current requirements with a qualified adviser before acting.