For a US person living in the UK, few three-letter acronyms cause more pain than PFIC. A Passive Foreign Investment Company is, in plain terms, most non-US pooled investments — UK unit trusts, OEICs, investment trusts, ETFs, and the funds inside a Stocks & Shares ISA. The US taxes them under a punitive default regime designed to remove any advantage from holding offshore funds. But you are not stuck with the default: two elections — Qualified Electing Fund (QEF) and mark-to-market (MTM) — can dramatically change the outcome. This guide explains the three possible treatments and how to choose.
What is a PFIC, and why does it matter?
A foreign company is a PFIC if it meets either an income test (75% or more of its gross income is passive) or an asset test (50% or more of its assets produce passive income). Almost every non-US pooled fund meets one of these, so for a US investor a UK OEIC or ETF is a PFIC. The significance is that the US applies special anti-deferral rules to PFICs that are far harsher than how it taxes a US mutual fund — turning an ordinary investment into a compliance and tax headache. We cover the ISA angle specifically in our guide to PFIC rules and UK ISAs.
The default regime: Section 1291 (the one to avoid)
If you make no election, your PFIC is taxed under the section 1291 'excess distribution' regime, and it is deliberately punitive. Gains on sale and 'excess distributions' are not taxed as capital gains. Instead they are spread back over the years you held the fund, taxed at the highest ordinary income rate for each of those years, and then hit with an interest charge for the 'deferral' — as if you had underpaid tax all along. The result can be an effective rate far above normal capital-gains tax, plus interest. The default regime also denies you the lower long-term capital-gains rates entirely.
Election 1: Qualified Electing Fund (QEF)
A QEF election is usually the most favourable treatment. It lets you include your share of the fund's ordinary earnings and net capital gains each year, much like a US mutual fund — and crucially preserves the character of the income, so long-term capital gains inside the fund keep their lower US rate. You pay tax annually on your share of the fund's income whether or not it is distributed, but you escape the punitive 1291 interest charge entirely.
The catch is information. To make a QEF election you need a 'PFIC Annual Information Statement' from the fund, giving you the ordinary earnings and net capital gain figures in the precise form the IRS requires. Most UK fund providers do not produce these, because they have no reason to cater to US tax rules. Without that statement, the QEF election is simply not available — which is why, in practice, QEF is often off the table for ordinary UK retail funds.
Election 2: Mark-to-market (MTM)
The mark-to-market election is the practical fallback when QEF is unavailable. Each year you 'mark' the fund to its year-end market value and include any increase as ordinary income (and deduct decreases, but only to the extent of previously included gains). You are taxed annually on unrealised appreciation, and the income is ordinary rather than capital — so you lose the preferential long-term rate — but you again avoid the brutal 1291 interest charge.
MTM is only available for 'marketable' PFIC stock — broadly, shares that are regularly traded on a qualifying exchange, which covers many listed ETFs and investment trusts but not all unlisted funds. Its big advantages are that it needs no cooperation from the fund (you just need year-end prices) and it stops the deferral interest from building. Its drawbacks are annual tax on paper gains and the loss of capital-gains treatment.
QEF vs MTM vs default: a quick comparison
In broad terms the preference order is QEF, then MTM, then the default — but availability usually drives the decision. QEF is best on paper yet rarely possible for UK retail funds; MTM is the workable middle ground for listed funds; and the punitive default is what catches people who never realised they held a PFIC at all.
- Section 1291 (default): highest ordinary rates spread over the holding period + interest charge. Capital-gains character lost. Worst outcome.
- QEF: annual tax on your share of fund income, capital-gains character preserved, no interest charge — but needs a PFIC Annual Information Statement most UK funds won't provide.
- Mark-to-market: annual tax on unrealised gains as ordinary income, no interest charge, needs only year-end prices — but only for exchange-traded ('marketable') funds.
Form 8621: the annual filing
Whichever treatment applies, PFICs are reported on Form 8621 — one per fund, every year. This is where you make and maintain a QEF or MTM election and report the income or gain. The form is notoriously time-consuming, and holding several PFICs means several forms, which is a major reason US persons in the UK are advised to avoid pooled foreign funds in the first place. There is a limited filing exception where your total PFIC holdings are small (broadly $25,000 or less, or $50,000 for joint filers) and you have no excess distribution or election to report, but you generally still owe tax under the rules even when a form is not required.
The timing trap: elections are best made early
Elections work best when made in the first year you own the PFIC. A QEF election made from year one gives clean QEF treatment throughout. Make it late and part of your gain can still be caught by the 1291 rules unless you also make a 'purging' election to clear the taint — an extra step with its own tax cost. The lesson is that PFIC treatment should be decided when you buy, not when you sell, which is why pre-investment planning matters so much for US persons abroad.
Why the ISA makes this worse
A Stocks & Shares ISA is tax-free in the UK but invisible to the US — the IRS does not recognise the wrapper, so the funds inside are taxed as PFICs and the ISA's gains are fully US-taxable. Worse, the 'tax-free' nature means there is no UK tax to generate a Foreign Tax Credit, so the US tax often lands with nothing to offset it. For a US person, an ISA full of UK funds can combine the punitive PFIC regime with a stack of Form 8621 filings and no foreign tax relief — a genuinely bad trifecta.
How to avoid PFICs altogether
The cleanest answer is usually to not hold PFICs. US persons in the UK often invest instead through US-domiciled funds (held in a US brokerage that accepts overseas-resident citizens), individual shares, or other non-PFIC structures, sidestepping the regime entirely. This needs care — some US brokers restrict UK-resident accounts, and you must weigh UK reporting-fund status too — but it removes the section 1291/QEF/MTM problem at the root. Our pre-immigration planning guide explains why cleaning up funds before you move is so valuable.
Coordinating with the UK side
PFIC is a US concept — the UK has its own, separate rules on offshore funds (the 'reporting' vs 'non-reporting' fund regime), which determine whether your gains are taxed as capital gains or income for UK purposes. A fund can be a US PFIC and a UK non-reporting fund at the same time, attracting unfavourable treatment on both sides. Getting an investment that works for both systems — non-PFIC for the US and reporting-fund for the UK — is the goal, and it rarely happens by accident.
Get PFIC treatment right before it compounds
PFIC is one of the most expensive areas of US/UK tax to get wrong, and one of the most avoidable. If you already hold foreign funds, the QEF-versus-MTM-versus-default analysis decides how badly you are taxed and how much paperwork you face; if you are still investing, structuring around PFICs altogether is usually better than electing into a less-bad version of them. Either way, this is specialist territory. A US tax specialist who understands UK investments can map your holdings, make the right elections in time, and stop a fund choice turning into years of punitive tax.
