You’ve spent years diligently filling your ISA allowance, building up a tidy tax-free nest egg. Then you move to Portugal — and suddenly the rules change completely. So what actually happens to your ISA when you become a non-UK resident, and what are your options?

It’s one of the most common questions I hear from clients who are planning their move to Portugal or have recently arrived. The good news is your ISA doesn’t disappear. The less good news is that it stops working the way you’re used to. Let me walk you through exactly what changes, what stays the same, and what you should consider doing about it.

What Happens to Your ISA When You Leave the UK

First, the basics. When you become non-UK resident, you lose the ability to contribute to your ISA. That annual £20,000 allowance? Gone. You cannot add a single penny once HMRC considers you non-resident, which typically happens under the Statutory Residence Test once you’ve been living in Portugal full-time.

However — and this is the crucial bit — your existing ISA remains intact. The investments inside it continue to grow, you can still hold them, and you can still withdraw from them. The ISA wrapper itself doesn’t break just because you’ve moved abroad.

What does change is the tax treatment. In the UK, ISA growth and withdrawals are completely tax-free. But Portugal doesn’t recognise the ISA as a tax-privileged wrapper. As far as the Portuguese tax authorities are concerned, your ISA is just another investment account. That means any gains, dividends, or interest generated inside your ISA may be taxable in Portugal.

This catches a lot of people off guard. You assume that because it’s “tax-free” in the UK, it must be tax-free everywhere. Unfortunately, that’s not how international tax works.

How Portugal Taxes Your ISA

Portugal taxes investment income under a few different categories, depending on what’s happening inside your ISA. Dividends from shares held in your ISA are typically taxed at a flat 28% rate in Portugal, or you can opt to include them in your general income and pay at your marginal rate if that works out lower.

Capital gains — when you sell investments inside your ISA at a profit — are also subject to Portuguese tax. For shares held less than 365 days, the gain is taxed at 28%. For shares held longer, there’s still a 28% rate unless you opt for aggregation with your other income. There are some nuances around this for EU-listed securities, but the core principle is clear: Portugal will want its cut.

Interest from cash ISAs follows a similar pattern — 28% flat rate or aggregation. The bottom line is that your ISA’s main benefit (tax-free growth) is effectively neutralised once you’re a Portuguese tax resident.

One important note: if you qualified for Portugal’s NHR (Non-Habitual Resident) regime before it closed to new applicants, foreign-source investment income may have been taxed at a flat 10% rate under the new 2024 rules, or potentially exempt under the older NHR rules depending on when you registered. If you’re still within your NHR period, it’s worth checking exactly how your ISA income is treated — it could be significantly more favourable.

Should You Keep Your ISA or Cash It In?

This is where it gets interesting, and where I see a lot of people making decisions without fully thinking through the implications. There are genuinely good reasons to keep your ISA, and equally good reasons to restructure.

Reasons to keep your ISA as it is:

If you think there’s any chance you’ll return to the UK within a few years, keeping your ISA intact makes sense. The moment you become UK resident again, the full ISA tax benefits spring back to life. You’ll also be able to start contributing again. Cashing in now and reinvesting later means you’d permanently lose that ISA “space” — you can’t retrospectively re-shelter those funds.

If your ISA holds investments with large unrealised capital gains, selling them triggers an immediate tax event in Portugal. Depending on the size of those gains, you might prefer to hold and manage the tax liability gradually over time.

Reasons to consider restructuring:

If you’re staying in Portugal long-term and your ISA is generating regular dividends or interest, you’re paying Portuguese tax on that income anyway — so the ISA wrapper isn’t giving you any benefit. In that case, you might achieve better tax efficiency by moving your investments into a structure that Portugal does recognise favourably, such as a compliant investment bond or a Portuguese-domiciled fund structure.

Additionally, some UK ISA providers don’t want non-resident clients. They may restrict your account, prevent you from making new investments within the ISA, or even ask you to transfer away. It’s worth checking your provider’s policy on non-resident holders — some are relaxed about it, others aren’t.

Alternative Structures for UK Expats in Portugal

If you do decide to restructure away from your ISA, the question becomes: where do you put the money instead? There are several options worth considering.

Compliant investment bonds (sometimes called insurance-based wrappers) are popular among expats because they can offer tax deferral. You don’t pay tax on the growth until you make a withdrawal, and even then, only the gain element is taxed. This can be significantly more efficient than holding directly-invested funds where dividends and gains are taxed as they arise.

Portuguese compliant funds — certain fund structures that meet EU reporting requirements can offer more straightforward tax treatment in Portugal. Your adviser should be able to identify funds that are “reporting” for Portuguese tax purposes.

Direct share holdings — if you prefer picking individual stocks, holding them outside an ISA in a standard dealing account is perfectly fine. You’ll pay capital gains tax when you sell, but you have more control over when that happens (which means you can manage your tax liability year by year).

The right answer depends entirely on your personal circumstances: how much is in the ISA, what’s invested there, your tax position in Portugal, how long you plan to stay, and your overall financial plan. There’s no one-size-fits-all solution, which is why I always recommend getting specific advice rather than making assumptions based on what worked for someone else.

The UK-Portugal Tax Treaty and Your ISA

The UK-Portugal Double Taxation Treaty exists to prevent you being taxed twice on the same income. In practice, most ISA income (dividends, interest, capital gains) will be taxable only in your country of residence — which is Portugal if you live here full-time.

UK dividends paid into your ISA may have UK withholding tax deducted at source (typically 0% for dividends from UK companies paid to individuals, but this can vary for certain types of income). Where UK tax is withheld, you can usually claim a credit against your Portuguese tax bill to avoid double taxation.

The treaty doesn’t magically make your ISA tax-free in Portugal. But it does ensure you’re not paying full tax to both countries on the same money, which is some comfort.

Practical Steps: What to Do With Your ISA When You Move

If you’re planning a move to Portugal or have recently arrived, here’s a sensible approach to your ISA:

First, check with your ISA provider whether they allow non-resident account holders. Some do, some don’t, and some have restrictions. Do this early — you don’t want a nasty surprise six months after arriving.

Second, take stock of what’s actually inside your ISA. How much unrealised gain is there? What income is it generating? This information is essential for making a good decision about whether to keep or restructure.

Third, understand your Portuguese tax position. Are you on NHR? What’s your marginal tax rate? How does your ISA income interact with your other income sources? A tax adviser who understands both UK and Portuguese systems is invaluable here.

Fourth, consider timing. If you’re going to sell investments, doing it in a tax year where your other income is lower can reduce the overall tax hit. There may also be advantages to selling before or after becoming Portuguese tax resident, depending on the specific circumstances.

Finally, don’t rush. Your ISA isn’t going anywhere. Taking a few months to get proper advice and make an informed decision is far better than making a hasty move you’ll regret. I’ve seen too many people cash in their ISAs immediately upon arrival without thinking through the tax consequences, only to realise later that a phased approach would have saved them thousands.

Frequently Asked Questions

Can I still contribute to my ISA if I live in Portugal?

No. Once you become non-UK resident, you cannot make any new contributions to your ISA. Your existing holdings remain in place, but the allowance is frozen until you return to the UK.

Will HMRC close my ISA if I move abroad?

HMRC won’t close your ISA, but your provider might restrict it. HMRC simply removes your eligibility to subscribe. The account continues to exist and your investments remain sheltered from UK tax — it’s the Portuguese tax treatment that changes.

Is ISA income taxable in Portugal even if I don’t withdraw it?

It depends on the type of income. Dividends and interest arising within the ISA are generally taxable in Portugal in the year they’re received, even if reinvested. Capital gains are only taxable when you actually sell (realise the gain). This distinction matters for planning purposes.

Should I transfer my ISA to a different provider before moving?

Potentially. If your current provider doesn’t accept non-resident clients, you’ll need to transfer to one that does — and it’s easier to do this while you’re still UK resident. Providers like interactive investor and Hargreaves Lansdown have different policies, so check before you move.

Can I open a new ISA if I return to the UK later?

Yes. If you become UK resident again, your full ISA eligibility is restored. You can subscribe to the current year’s allowance and your existing ISA continues as normal. There’s no penalty for the years you missed while abroad.

What to Do Next

Your ISA is likely one of several financial assets that need reviewing when you move to Portugal. The key takeaway is this: don’t assume it works the same way here as it did in the UK, but equally don’t panic and cash everything in without a plan.

If you’d like to discuss how your ISA fits into your overall financial picture as an expat in Portugal, get in touch with our team. We specialise in helping UK expats navigate exactly these kinds of cross-border planning questions.

Matthew Renier is a Chartered Financial Adviser at Arthur Browns Wealth Management, based in the Algarve, Portugal. He has over 20 years of experience helping British expats manage their pensions, investments, and financial planning across borders.

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