This guide is for families who invest on both sides of the Atlantic: Americans living in Britain, Britons with US accounts, and couples where only one partner is a US person. The short answer is that one portfolio can work across two markets, but the same fund can be taxed very differently depending on who owns it, where the fund is domiciled and which account holds it, so the structure matters as much as the investments.
What makes a US–UK portfolio different from an ordinary one?
An ordinary portfolio has one tax system to satisfy. A cross-border portfolio has two, and they disagree about which funds are acceptable, which accounts are tax-free and which exchange rate to use. The investment principles are unchanged, but the vehicle holding each investment can change the after-tax result by more than the investment choice itself. Three things drive the difference:
- Who owns the asset. The United States taxes its citizens and green-card holders on worldwide income wherever they live[9], so a UK-resident American is taxed by both countries on the same dividend or gain. A non-American spouse living in the UK is generally reached by the US only through withholding on US-source income.
- Where the fund is domiciled. The UK has special rules for funds based outside the UK; the US has the PFIC regime for funds based outside the US. A fund that is simple for one country can be a problem for the other.
- Which wrapper holds it. ISAs, SIPPs, 401(k)s, IRAs and Roth IRAs each shelter tax at home. Only some of that shelter is recognised by the other country, mostly through the pension articles of the US–UK treaty.
So the portfolio needs designing person by person and account by account. Tax treatment depends on individual circumstances and the rules change; what follows is general information, not advice.
Does it matter where a fund is domiciled?
Yes. For UK tax, any fund based outside the UK is an offshore fund, and unless it has HMRC “reporting fund” status, gains on disposal are taxed as income (an “offshore income gain”) rather than as capital gains[20]. For US tax, most pooled funds based outside the US are likely to be PFICs in the hands of a US person[8]. The two rules push in opposite directions.
From the UK side, a US-domiciled exchange-traded fund (ETF) is an offshore fund. Many offshore funds, including some US-domiciled ones, have obtained reporting status so UK investors get capital gains treatment. A reporting fund tells investors their share of its income each year; where that exceeds what was paid out (the “excess reportable income”), the investor is taxed on it as if received six months after the end of the fund’s reporting period, and the same amount is added to their CGT base cost[20]. HMRC publishes a monthly list of reporting funds[21], which UK taxpayers can check before buying.
From the US side, a PFIC is a foreign corporation where 75% or more of gross income is passive, or at least 50% of its assets produce passive income[8]; a UK OEIC, unit trust or Irish ETF will usually qualify. The default “excess distribution” regime taxes gains and larger distributions as ordinary income spread back over the holding period, with an interest charge. A qualified electing fund (QEF) election needs an annual statement many UK funds do not provide; the mark-to-market election taxes each year’s rise in value as ordinary income. Each PFIC generally needs a Form 8621, although PFICs held through a US IRA are outside the regime[8]. The PFIC rules are covered in depth in ISAs, UK funds and PFIC rules for Americans.
| Holding | UK-resident non-US person | UK-resident US person |
|---|---|---|
| Individual US or UK company shares | UK CGT on gains; UK dividend tax; US withholding on US dividends | Taxed in both; no fund-level problems; foreign tax credits relieve most double tax |
| UK OEIC, unit trust or investment trust | Standard UK treatment | Likely PFIC in the US: Form 8621; punitive default rules |
| Irish or Luxembourg UCITS ETF | Offshore fund: needs reporting status for CGT treatment | Likely PFIC in the US |
| US-domiciled ETF or mutual fund | Offshore fund: needs reporting status for CGT treatment; may be hard to buy on UK platforms | Normal US treatment; offshore fund for UK tax: check reporting status |
For a US person, what satisfies both systems is often narrow: individual shares, or US-domiciled funds that also hold UK reporting status. For a non-American partner, UK funds and UCITS ETFs are generally straightforward, so couples often end up with two portfolios holding similar underlying investments.
How much US tax is withheld on US dividends for UK residents?
For a UK resident who is not a US person and has given the payer a Form W-8BEN, US tax on portfolio dividends is capped at 15% under Article 10 of the US–UK treaty[1][4]. Without that form, the US generally withholds 30%[3]. Where the beneficial owner is a UK pension scheme, Article 10(3) removes US tax on the dividend entirely, provided the dividends are not derived from carrying on a business[1].
The UK then taxes the dividend and credits the US tax up to the treaty rate, so in a taxable account the 15% is mostly offset. In an ISA, where no UK tax is due, it is a final cost.
A US citizen or green-card holder gives US payers a Form W-9, so there is normally no withholding; the dividend goes on their US return and is taxed by the UK too. Under treaty Article 24(6), the UK credits only the US tax it could have charged a UK resident who is not a US citizen (15% on portfolio dividends), and the US then credits the UK tax remaining after that[1]. Dividends from UK companies can count as qualified dividends in the US because the UK treaty is on the IRS’s approved list[5]. For 2026 the 0% US rate on qualified dividends and long-term gains applies up to $98,900 of taxable income for joint filers, 15% to $613,700, and 20% above[6]. The 3.8% net investment income tax can apply above $250,000 of modified adjusted gross income for joint filers ($200,000 single)[7].
| Account | US tax | UK tax | Kept |
|---|---|---|---|
| General investment account, W-8BEN in place | $1,500 (15%) | $3,575 at 35.75% less $1,500 credit = $2,075 | $6,425 |
| General investment account, no W-8BEN | $3,000 (30%) | $2,075 (credit capped at treaty 15%) | $4,925, unless the excess is reclaimed from the IRS |
| Stocks and Shares ISA | $1,500 (15%) | None | $8,500 |
| SIPP or workplace pension (treaty relief claimed) | None | None while invested; income tax on withdrawal | $10,000 invested |
These are illustrative figures from published rates, not planner output; the result for any person depends on their income, allowances and the paperwork their provider holds.
Which account should hold which investment?
Asset location means deciding which investments sit in which account. In a cross-border household it is done per person, because an ISA is fully tax-free for the non-American partner but taxable in the US for the American one, while pensions are the wrapper both countries broadly respect under the treaty[1].
Treaty Article 18(1) says income earned inside a pension scheme established in the other country is taxed as the member’s income only when, and to the extent that, it is paid out[1], and Article 1(5) exempts that paragraph from the “saving clause” that otherwise lets the US tax its citizens as if the treaty did not exist. The technical explanation lists IRAs and Roth IRAs among US pension schemes, alongside UK registered and personal pension schemes[2]. So a UK-resident American’s SIPP can grow without annual US tax, and a UK resident’s IRA without annual UK tax. Withdrawals are a separate matter, covered in UK pensions for US persons and US retirement accounts when you live in the UK.
| Account | UK treatment | US treatment for a US person | Typical fit |
|---|---|---|---|
| Stocks and Shares ISA (£20,000 a year) | No UK tax on income or gains | Not recognised; income and gains taxable; UK funds inside may be PFICs | Very efficient for non-US partner; limited value for a US person, and then usually individual shares |
| Cash ISA | Tax-free interest; limit falls to £12,000 for under-65s from 6 April 2027[15] | Interest taxable | Cash reserve for the non-US partner |
| SIPP / workplace pension | Tax relief on contributions; tax-free growth; taxed on withdrawal | Growth deferred under treaty Art. 18(1) | Common ground for both partners; can suit higher-yielding assets |
| 401(k), Traditional IRA | Growth deferred under Art. 18(1); taxed on withdrawal | Tax-deferred; PFIC rules do not apply inside | Where US-domiciled funds sit comfortably |
| Roth IRA | Growth deferred; qualifying withdrawals can stay exempt if treaty conditions are met[1] | Tax-free if qualified | Long-term growth assets for the US person |
| UK general investment account | CGT at 18%/24% after £3,000; dividend tax after £500 | Fully taxable; avoid PFICs | Individual shares; reporting funds for the non-US partner |
| US brokerage account | Taxable in UK; US funds are offshore funds | Standard US treatment | US-domiciled funds with UK reporting status for a US person |
In practice a couple may find the non-American partner’s ISA allowance the cleanest shelter, while the American partner leans on pensions and US retirement accounts and holds individual shares or dual-compliant funds in taxable accounts. Where one partner is not a US person, there is also a US estate tax point: a non-US citizen who is not US-domiciled faces a US estate return if their US-situated assets, which include shares in US companies, exceed $60,000 at death, subject to the US–UK estate tax treaty[12]. That can argue for holding US shares through non-US funds or in the American partner’s name. Estate questions are covered in UK inheritance tax and US estate tax.
For new arrivals, since 6 April 2025 someone in their first four years of UK residence after at least ten years abroad can claim relief from UK tax on foreign income and gains, at the cost of that year’s personal allowance and CGT annual exempt amount[22]. That can ease the non-reporting fund problem for an American arriving with a US brokerage account, but only for those four years.
Rates are moving. UK dividend ordinary and upper rates rose by two percentage points from 6 April 2026, and the Finance Act 2026 sets savings income rates of 22%, 42% and 47% for 2027/28, from 6 April 2027[16][17], which changes which assets gain most from a tax-free wrapper.
Should a family that spends in sterling hold dollar assets?
Often yes, but with a deliberate balance. US companies make up a large share of global equity markets, so a diversified portfolio carries significant dollar exposure whatever the fund’s domicile. The question is whether the assets meant to fund the household’s spending are in the same currency as that spending.
A family retiring in the UK and spending sterling is exposed if sterling strengthens, because each dollar then buys fewer pounds; a family retiring in the US faces the reverse. Currency-hedged share classes reduce the exposure at a cost, and for US persons a hedged class of a non-US fund is still a PFIC. Matching cash and bonds to the currency of near-term spending is simpler. Past episodes are set out in GBP/USD currency risk in retirement. Currency also changes the tax result: the UK measures gains in sterling and the US in dollars, so one sale can be a gain in one country and a loss in the other, as Tax reporting for investors with US and UK accounts shows.
Where can a UK-resident American invest?
Fewer places than most investors. Under FATCA, the US Foreign Account Tax Compliance Act, non-US financial institutions must report accounts held by US persons or face withholding[10], and some UK firms decline US-person clients rather than take that on. Some US brokers restrict accounts for customers living abroad. Policies change, so confirm a provider’s current position on both residence and citizenship before moving assets.
US-domiciled ETFs have also commonly not been offered to UK retail investors on UK platforms because of product-disclosure rules. The FCA’s Consumer Composite Investments regime replaces those rules: its legislation took effect on 6 April 2026, with an optional transition period, and the rules come fully into force on 8 June 2027[26]. Whether US fund providers choose to offer their funds to UK retail investors is up to them, and it is too early to say whether US funds will become widely available.
Some brokers do accept US persons resident in the UK and offer both markets in one account; their existence is not a recommendation of any of them. Suitability depends on costs, investor protection, how the account is reported to each tax authority and your circumstances. Accounts at non-US institutions also count towards the FBAR and Form 8938 thresholds.
Are investment bonds a good fit for Americans in the UK?
Usually not. For a UK taxpayer a bond can be efficient: tax is deferred, 5% of the premium can be withdrawn each year for twenty years without an immediate charge, and top-slicing relief can reduce the tax on gains[23]. For a US person the same bond often fails the US definition of life insurance, so its growth can be taxed in the US every year[11].
In the UK, investment bonds are life insurance policies. Gains are “chargeable event gains”, taxed as income, when the policy is surrendered, matures or is assigned for value, or when withdrawals exceed the cumulative 5% allowance (one-twentieth of each premium a year, up to 100%)[23]. On a UK (onshore) bond, basic-rate tax is treated as already paid on the gain, but that credit is not repayable[23]. Gains on foreign (offshore) policies normally carry no such credit. Time-apportionment relief can reduce the gain for periods of non-UK residence, on foreign policies and on UK policies issued (or varied or assigned) on or after 6 April 2013[23][24], which matters for people who move between the two countries.
In the US, Section 7702 sets tests a contract must pass to be treated as life insurance. If a contract that is life insurance under local law fails them, its “income on the contract”, broadly the annual growth in cash value, is ordinary income each year[11]. UK and offshore bonds are designed around UK rules, not Section 7702. So the US may tax growth year by year while the UK taxes it only at a chargeable event, possibly many years later. Foreign tax credits work best when both countries tax the same income in the same year, so the mismatch can leave a US person paying tax twice or relying on complex carryovers. The US treatment of a particular contract depends on its terms and needs specialist US tax advice.
A bond that is tax-efficient for one partner can be unsuitable for the other. Who owns it and whose life is assured need checking from both countries’ point of view before investing.
Worked example: top-slicing relief on a bond gain (computed in Edale’s planner)
This example reproduces HM Revenue & Customs’ own published calculation (Insurance Policyholder Taxation Manual, IPTM3850, Example 1)[25], set in the 2022/23 tax year with that year’s bands. A fictional policyholder with £45,000 of employment income fully surrenders a UK life insurance bond held for five years, realising a £50,000 chargeable event gain. Basic-rate tax of 20% is treated as paid on the gain. It is illustrative only: it shows how the relief works, not what any investor would pay, and current bands and rates differ.
| Step | Amount |
|---|---|
| Chargeable event gain on full surrender | £50,000 |
| Complete years the policy was held | 5 |
| “Annual equivalent” (slice): £50,000 ÷ 5 | £10,000 |
| Basic-rate tax treated as paid (20% of the gain) | £10,000 |
| Tax on the gain before relief, after that credit | £8,846 |
| Tax on the gain after top-slicing relief | £4,230 |
| Top-slicing relief | £4,616 |
Added to £45,000 of salary, the whole gain would push most of it into the higher-rate band. Top-slicing relief asks what the tax would have been had the gain arisen evenly, £10,000 a year, over five years: the tax on one slice, on top of the salary, is worked out and multiplied by five. In HMRC’s example, less than half of a £10,000 slice reaches the higher-rate band, so much less of the gain attracts higher-rate tax. The relief is £4,616 and the tax payable falls to £4,230, matching HMRC’s own figures.
For a UK taxpayer, this lets gains be timed for a lower-income year, such as early retirement. For a US person, if the US has already taxed the growth year by year, the UK tax at surrender may fall in a year with no matching US income to credit it against. The planner models bond gains and top-slicing for UK tax; the US treatment of a particular bond is a matter for a US tax adviser. Results depend on the stated assumptions and are not guaranteed.
How the Edale Wealth Hub helps
A cross-border portfolio is hard to see whole when it sits with different providers, in two currencies and under two tax systems. The Edale Wealth Hub brings these views together.
- My Investments. For accounts the adviser has linked (currently Interactive Brokers UK and US accounts), clients see consolidated valuations, holdings, transactions and performance across US and UK accounts, with a £/$ toggle. Income received is shown with tax withheld, split between taxable and tax-advantaged accounts, so the cost of US withholding in an ISA or a taxable account is visible rather than buried in a statement.
- PFIC flags and allowance tracking. The portal’s US tax summary flags holdings that may be PFICs, and ISA allowance tracking shows how much of the £20,000 (and £9,000 per Junior ISA) has been used.
- The cashflow planner. Advisers model the household across both countries at once: ISAs, SIPPs, workplace and defined benefit pensions, 401(k)s, IRAs, Roth IRAs, US and UK taxable accounts, and onshore and offshore investment bonds with chargeable gains and top-slicing relief. It applies UK and US federal tax and, for US persons, their interaction through foreign tax credits and treaty treatment, so the plan shows what the household keeps. It also identifies non-US funds held by US persons that may be PFICs.
- Currency and withdrawal order. Twelve historic GBP/USD and GBP/EUR currency episodes can be applied to the plan, and alternative orders of drawing from accounts can be compared side by side.
There are limits. My Investments covers linked Interactive Brokers accounts, not every platform. The planner does not model US estate tax. The US tax summary is a 1099-style summary to share with an accountant or tax preparer; it is not a Form 1099 or a tax return, and Edale does not prepare US tax returns. Whether a given structure suits you depends on your circumstances; arrange a conversation or read more about the cashflow planner.
Frequently asked questions
Can a US citizen living in the UK open a Stocks and Shares ISA?
Yes. A UK-resident US citizen can open and use an ISA, and the UK treats it as tax-free in the normal way. The US does not recognise ISAs, so income and gains inside it must still be reported and taxed on the US return. If the ISA holds UK or Irish funds, they are likely to be PFICs with extra reporting. Individual shares avoid the PFIC problem but not the US tax.
What rate of US tax is withheld on US dividends for a UK resident?
For a UK resident who is not a US person and has given the payer a Form W-8BEN, the US–UK treaty caps tax on portfolio dividends at 15%. Without the form the default is 30%. UK pension schemes can claim 0%. US citizens give a Form W-9 instead and report the dividends on their US return.
Is a US-domiciled ETF a problem for UK tax?
It can be. For UK tax it is an offshore fund, so gains are taxed as income unless the fund has HMRC reporting-fund status, in which case gains fall under capital gains tax. HMRC publishes a monthly list of reporting funds. Reporting funds can also create taxable “excess reportable income” even when nothing is paid out.
Why are UK funds a problem for Americans?
Most pooled funds based outside the US, including UK unit trusts, OEICs and Irish ETFs, are likely to be passive foreign investment companies for a US shareholder. The default PFIC rules tax gains as ordinary income with an interest charge, and each fund generally needs its own Form 8621. PFICs held inside a US IRA are outside these rules.
Does the US tax growth inside a UK pension?
Under Article 18(1) of the US–UK treaty, income earned inside a pension scheme established in the other country is taxed as the member’s income only when it is paid out. That paragraph is excepted from the saving clause, so it also protects US citizens in UK schemes. Contributions and withdrawals follow separate rules.
Are offshore investment bonds suitable for US persons?
Often not. Many UK and offshore bonds fail the US definition of life insurance in Section 7702, in which case the annual growth can be taxed in the US as ordinary income, while the UK taxes the gain only at a later chargeable event. The mismatch can make foreign tax credits hard to use. Specialist US advice is needed.
Should my non-American spouse hold our US shares?
Not necessarily. A non-US citizen who is not US-domiciled faces US estate tax filing if US-situated assets, including US company shares, exceed $60,000 at death, subject to the US–UK estate tax treaty. Who holds which assets affects income tax, estate tax and reporting in both countries, so ownership is worth reviewing with an adviser.
Sources
- US Treasury — Convention between the United States and the United Kingdom for the avoidance of double taxation (2001) (accessed September 2026)
- US Treasury — Technical Explanation of the US–UK Income Tax Convention and Protocol (accessed September 2026)
- IRS — NRA withholding (accessed September 2026)
- IRS — About Form W-8BEN (accessed September 2026)
- IRS — Notice 2024-11: treaties meeting the requirements of section 1(h)(11)(C)(i)(II) (accessed September 2026)
- IRS — Revenue Procedure 2025-32 (2026 inflation adjustments) (accessed September 2026)
- IRS — Net investment income tax (accessed September 2026)
- IRS — Instructions for Form 8621 (accessed September 2026)
- IRS — Publication 54, Tax guide for US citizens and resident aliens abroad (accessed September 2026)
- IRS — Foreign Account Tax Compliance Act (FATCA) (accessed September 2026)
- US Code — 26 USC 7702, Life insurance contract defined (accessed September 2026)
- IRS — Some nonresidents with US assets must file estate tax returns (accessed September 2026)
- GOV.UK — Individual Savings Accounts (ISAs) (accessed September 2026)
- GOV.UK — Junior Individual Savings Accounts (accessed September 2026)
- HM Treasury/HMRC — Cash ISA limit reduction (accessed September 2026)
- GOV.UK — Tax on dividends (accessed September 2026)
- HMRC — Change to tax rates for property, savings and dividend income: technical note (accessed September 2026)
- GOV.UK — Capital Gains Tax: allowances (accessed September 2026)
- GOV.UK — Capital Gains Tax: rates (accessed September 2026)
- HMRC — HS265 Offshore funds (accessed September 2026)
- HMRC — Offshore funds: list of reporting funds (accessed September 2026)
- HMRC — Check if you can claim the 4-year foreign income and gains regime (accessed September 2026)
- HMRC — HS320 Gains on UK life insurance policies (2026) (accessed September 2026)
- HMRC — HS321 Gains on foreign life insurance policies (2026) (accessed September 2026)
- HMRC — Insurance Policyholder Taxation Manual IPTM3850: top slicing relief examples (accessed September 2026)
- Financial Conduct Authority — PS25/20 Consumer Composite Investments (accessed September 2026)