By Jonathan Laws, ACA Ch.FCSI | Senior Financial Adviser, Cameron James | cjfinance.co.uk | June 2026
If you have recently returned to the UK after working in the United States, there is a reasonable chance you have seen the adverts. They appear on Instagram, on LinkedIn and across social media. The message is always a variation of the same claim: convert your 401(k) to a Roth IRA now, before the window closes, and use the Foreign Income and Gains (FIG) regime to avoid paying UK tax on the conversion.
That framing contains a significant problem. It implies that without the FIG regime, you would face a UK tax bill on your Roth conversion. The general consensus among cross-border tax advisers is that you would not. The UK tax problem these adverts are selling you protection from does not, under the current consensus, exist.
That does not mean there is nothing to think about. There is a genuine reason to take cross-border financial advice on this now, as the consensus view could change in light of recent HMRC changes in 2025. But it is not the reason in the adverts, and understanding the difference matters if you want to make the right decision.
What Is a 401(k) to Roth IRA Conversion?
A Roth conversion is the process of moving money from a pre-tax retirement account, typically a traditional 401(k) or traditional IRA, into a Roth IRA.
In a traditional 401(k) or traditional IRA, contributions are made from pre-tax income. The money grows tax-deferred, and withdrawals in retirement are taxed as ordinary income in the US.
A Roth IRA works differently. Contributions are made from after-tax income. The money then grows free of tax, and qualified withdrawals in retirement are free of US federal income tax.
When you convert from a traditional 401(k) or IRA to a Roth, the amount converted is treated as taxable income in the US in the year of conversion. You pay US federal income tax on it at your marginal rate. In exchange, the money moves into the Roth wrapper, where future growth and qualifying withdrawals will be free of US tax.
The conversion is always a taxable event in the US. That part is not in dispute.
The question that matters for someone returning to the UK is: does the conversion also create a UK tax liability?
Returned to the UK with a 401(k) or IRA still in the US?
An FCA-regulated adviser gives you the honest position on your Roth conversion under the US-UK treaty, then builds a cross-border plan around your actual circumstances rather than a manufactured deadline. No jargon. No pressure.
Does a Roth Conversion Create a UK Tax Liability?
The general consensus among cross-border tax advisers is no.
The interpretation of most tax advisers is that, Under the US-UK Double Taxation Agreement (DTA), a 401(k) and traditional IRA are treated as pension schemes. The Roth conversion is not a distribution to you. It is an internal reorganisation within the US pension wrapper. You are not receiving the money. You are moving it from one retirement account structure to another.
Because no distribution is made to you as an individual, the conversion does not constitute a taxable receipt in the UK. HMRC does not treat it as income arising in your hands. The general view, consistently held among many advisers specialising in this area, is that a Roth conversion by a UK resident does not trigger a UK tax charge.
Once the money is in the Roth, the picture for future withdrawals is also generally favourable. Under Article 17(1)(b) of the DTA, where a payment from a pension scheme established in one country would have been exempt from tax there had the recipient been resident there, that amount must also be exempt in the country of residence. Qualifying Roth distributions are free of US federal income tax. Under the treaty mirror principle, the UK is expected to apply the same treatment. HMRC's own Double Taxation Relief Manual at DT19853 reflects this position.
The practical result: the general view is that a Roth conversion does not create a UK tax event, and qualifying distributions from a Roth IRA to a UK resident are also not subject to UK tax.
| IMPORTANT NOTE This reflects the general consensus and not a definitive HMRC ruling. The treaty analysis involves complexity and individual circumstances vary. This is not tax advice. Always seek specialist cross-border tax advice before acting. |
What the Adverts Are Actually Claiming
The adverts targeting UK returnees with 401(k) or IRA assets claim that the Foreign Income and Gains (FIG) regime, introduced from 6 April 2025, gives you four years of UK tax relief on Roth conversions.
The implication of that framing is that without the FIG regime, your Roth conversion would absolutely be taxable in the UK. The FIG window is presented as the protection. Convert now, before the four years run out, before you lose your chance.
That is not an accurate description of the current position. The general consensus is that the conversion is not taxable in the UK regardless of whether the FIG regime applies. The FIG regime is not solving a problem that would otherwise exist. It is being used to manufacture urgency around a tax exposure that, under the current and long-standing consensus, does not exist for most people in this situation.
Presenting the FIG regime as the thing standing between you and a UK tax bill on your Roth conversion is not straightforward advice. It is marketing. And it is designed to make you act quickly, before you think too carefully about whether the premise is actually correct. It might well be that HMRC does start taxing conversions, but that is not the consensus view at this point of time, and even if they did, it would likely be heavily contested in the courts, given it would upend decades of precedent.
The honest version: The FIG regime is a genuine piece of tax legislation. For some returning non-doms it has real and important uses. But it is not the reason your Roth conversion is free of UK tax. The DTA is. Advisers who present the FIG regime as the primary reason to convert are not giving you the full picture.
What the Foreign Income and Gains Regime Actually Does
The FIG regime replaced the old remittance basis for non-domiciled individuals from 6 April 2025. Under FIG, an individual who has not been a UK tax resident for at least ten of the previous twenty tax years and who becomes a UK resident can elect to exempt foreign income and gains from UK tax for their first four years of UK residence.
For someone returning to the UK after ten or more years in the United States, this can be relevant across a range of foreign income and gains. Rental income from a US property, gains on investments held outside a retirement wrapper, interest from US accounts: the FIG regime can shelter all of these during the four-year window.
For Roth conversions specifically, the FIG regime is not the operative protection. The conversion is not taxable in the UK under the treaty in the first place. The FIG regime is neither needed nor, in the context of a Roth conversion, the reason for the favourable tax treatment.
Some advisers have suggested that the FIG regime might provide an additional layer of cover in the event that HMRC were ever to challenge the treaty position on Roth conversions and apply any revised view retrospectively. That is possible in theory, though HMRC rarely acts retrospectively and there is no confirmation that the FIG regime would even apply in that scenario. This is speculative rather than settled planning. It might well be prudent planning, but you still need to make a sensible and informed decision, and not be rushed into any course of action.
The Genuine Reason to Think About This Now
There is a real reason to take advice on your Roth conversion now. It is just not the one in the adverts.
HMRC is actively reviewing how it applies the US-UK Double Taxation Agreement to US retirement assets. In March 2025, HMRC published updated guidance on lump sum distributions from traditional US pension plans, applying the treaty's saving clause in a way that reversed a long-standing consensus about UK tax exemption for those payments.
The Roth conversion position is different and is not directly affected by that March 2025 guidance. The Roth is not treated as a pension in the same way that a traditional 401(k) is for lump sum distribution purposes, and the treaty mechanism that protects Roth treatment sits on different legal grounds. The general view is that the March 2025 guidance does not change the Roth consensus, although it could.
However, the broader direction of travel is clear. HMRC is looking at how US pension assets are taxed in the UK. It has already shifted its position in one significant area. The Roth consensus has held for years and remains the prevailing view, but no one can guarantee that HMRC will not look at this area more closely in future.
That is the genuine reason to consider acting now. Not a four-year countdown. Not a qualification window. But the fact that a favourable consensus that has been stable for years is operating in an environment where HMRC is actively revisiting related questions. Getting specialist cross-border financial advice, reviewing your position, and making a considered decision while the current consensus holds is prudent. It is not the same as panic-converting because an advert told you the window was closing.
What a Proper Roth Conversion Plan Should Cover
For most people returning to the UK with US retirement assets, the Roth conversion question does not exist in isolation. A proper cross-border financial plan should address all of the following.
Your US Tax Position on Conversion
The converted amount is taxable income in the US in the year of conversion. Depending on your income, your bracket, and available deductions, the US tax cost can be significant. Spreading conversions across multiple years is often more efficient than a single large conversion. A specialist adviser can model the optimal approach based on your self-assessment position and US filing obligations.
Whether You Qualify for the FIG Regime
If you have not been a UK tax resident for at least ten of the previous twenty tax years, you may qualify for the FIG regime. The FIG regime has genuine planning uses beyond Roth conversions and is worth understanding in full, particularly for rental income, investment gains, and interest from US accounts held outside a pension wrapper.
Your Composition of Assets
The planning for a traditional IRA or 401(k) is meaningfully different from that for a Roth. The March 2025 HMRC guidance on lump sum distributions makes it more important than ever to understand what you hold and how each element is treated under the DTA.
Your Drawdown Timeline
When you intend to draw on these assets, in what amounts, and whether those withdrawals will be periodic or lump sum, all affect the planning. The structure of withdrawals matters as much as the conversion decision itself.
Estate Planning
From April 2027, unspent pension assets held in UK pension wrappers are expected to come within the scope of UK inheritance tax. US retirement assets sit outside UK pension wrappers and are treated differently, but the overall picture should be reviewed as part of any cross-border financial plan. This is an area where taking early, considered advice matters.
JONATHAN LAWS | Senior IFA, Cameron James
“The volume of enquiries we receive from people who have seen these adverts is significant, and the misunderstanding they create is real. Clients come to us believing they have a UK tax problem that needs solving urgently. In most cases, under the current consensus, the problem does not exist in the way the advert described. That does not mean there is nothing to think about. HMRC is actively revisiting how it applies the treaty to US pension assets, and that is a genuine reason to take advice now. But the reason to act is the evolving regulatory environment, not a four-year countdown that has been manufactured to make you book a consultation.”
Why Speak to Cameron James?
Cameron James Ltd is an FCA-authorised financial planning firm specialising in cross-border financial advice. Our advisers working with US-connected clients hold individual SEC authorisation to advise on US retirement assets, providing regulated, accountable advice on both the UK and US sides of the planning.
We do not run campaigns built on manufacturing urgency around tax exposures that may not exist. We give clients the honest position, explain what the consensus is and where the genuine uncertainty lies, and build plans around their actual circumstances.
If you are returning to the UK with a 401(k), traditional IRA, or existing Roth IRA, the question of how to handle those assets is important and the landscape is genuinely changing. You deserve a straight answer, not a short form asking whether you qualify for a four-year window.
Speak to a Cameron James adviser
If you are returning to the UK with a 401(k), traditional IRA, or existing Roth IRA, do not act on what an advert has told you. Speak to an adviser who will give you the full picture. Cameron James is FCA-authorised, and our advisers hold the individual authorisation required to advise on US retirement assets.
Frequently Asked Questions
Under the general consensus, no. A Roth conversion is an internal reorganisation within the US pension wrapper, not a distribution to you as an individual. The prevailing view among cross-border tax advisers is that it does not constitute a taxable event in the UK under the US-UK Double Taxation Agreement. This is not a definitive HMRC ruling, and you should take specialist advice on your specific circumstances.
The FIG regime does provide a four-year exemption from UK tax on foreign income and gains for qualifying new UK residents. However, for a Roth conversion, the general consensus is that there is no UK tax to relieve in the first place. The FIG regime is not the protection. The US-UK Double Taxation Agreement is. Adverts that present the FIG four-year window as the primary reason to convert are not giving you an accurate picture.
The FIG regime has a four-year window for qualifying individuals. But for Roth conversions specifically, the FIG regime is not the operative protection under the current consensus. The genuine reason to consider acting now is that HMRC is actively reviewing how it applies the DTA to US pension assets, and a consensus that has been stable for years is worth acting on while it holds. That is a different and more accurate reason than the one in the advert.
Not directly. In March 2025, HMRC published updated guidance affecting lump sum distributions from traditional US pension plans. The general view is that this guidance does not apply to Roth conversions, which involve a different legal mechanism under the treaty. However, HMRC is clearly reviewing how the DTA applies to US pension assets more broadly. Taking advice now, while the current consensus on Roth treatment holds, is a sensible approach.
Whether to convert before or after returning, and how much to convert in any given year, depends on your US tax bracket, the size of your retirement assets, your income projections, your drawdown timeline, and your overall financial plan. There is no universal answer. The key is to make the decision as part of a properly considered cross-border financial plan, not in response to an advert. Speak to Cameron James to get the full picture for your specific circumstances.
If you paid US federal income tax on a Roth conversion and were a UK resident at the time, the foreign tax credit mechanism may be relevant to your overall position. This requires detailed analysis of your US and UK self-assessment filings for the years in question. Speak to a cross-border tax adviser who can review the specific filings.
The FIG regime, introduced from 6 April 2025, replaced the remittance basis available to non-domiciled individuals. Under FIG, qualifying individuals can elect to exempt foreign income and gains from UK tax for their first four years of UK residence, without the need to keep funds outside the UK. The old remittance basis required that income and gains remained unremitted to the UK to be sheltered. FIG is simpler in structure but has a defined four-year limit. Whether you qualify and whether it benefits your position depends on your specific residency history.
HMRC's Double Taxation Relief Manual is the primary reference. The relevant section for Roth IRA treatment is DT19853. The US-UK treaty text is published on GOV.UK. For the FIG regime, HMRC's guidance is also published on GOV.UK. Note that guidance in this area is actively being updated and you should verify that you are reading the most current version.
Further Reading
The following pages provide deeper context on topics covered in this article:
| DISCLAIMER This article is for informational purposes only and does not constitute financial, tax, or legal advice. Tax laws and treaty interpretations are subject to change, and individual circumstances vary. Always seek independent specialist advice before making any financial decisions relating to your pension or retirement assets. This article reflects the general consensus among cross-border tax advisers as of the date of publication and does not constitute a definitive HMRC ruling or legal opinion. The treaty analysis referenced in this article involves complexity. HMRC guidance and treaty interpretations may change. References to the US-UK Double Taxation Agreement, the Foreign Income and Gains regime, and HMRC guidance are for informational purposes only. Cameron James is authorised and regulated by the Financial Conduct Authority. Advisers working with US-connected clients hold individual regulatory authorisation appropriate to the advice provided. |