SDOP When Your Unreported Account Is a UK ISA or SIPP

A UK ISA and a UK SIPP are both reportable foreign accounts for a US person, whether or not anything inside them was ever taxable, so both belong in a Streamlined Domestic Offshore Procedure submission if they were left out. What differs is what each does to that submission. An ISA is invisible to the IRS as a wrapper, so the question becomes what the funds inside it are — usually passive foreign investment companies, with their own reporting and their own, mostly closed, elections. A SIPP raises a treaty position and a trust-form question instead, and almost none of the PFIC machinery.

This is written for someone resident in the United States: a Briton who moved to America, or an American who came home, leaving a stocks-and-shares ISA or a self-invested personal pension behind. Almost all the guidance on these wrappers addresses the opposite person — the American still living in Britain — and the route it points at is not the one open to you.

The two failures are different, and only one of them is about tax

There are two separate obligations here, and a tax-free wrapper only ever touches one of them.

Reporting comes first and has nothing to do with whether a penny of tax was due. An ISA held with a UK provider and a SIPP held with a UK administrator are foreign financial accounts. The FBAR is required once the aggregate value of your foreign accounts crosses the $10,000 FBAR aggregate threshold at any time in the calendar year — FinCEN Form 114, as the IRS sets out — so a current account you barely use and an ISA you forgot about can cross it between them. Form 8938 sits alongside it at its own thresholds, on the return rather than with FinCEN.

Taxing comes second. The ISA's exemption is a creature of UK law: HMRC's own description is that you pay no UK tax on interest, income or gains inside the wrapper. That exemption is granted by the United Kingdom, to the United Kingdom's tax. It says nothing to the IRS, which looks straight through the wrapper to the investments held in it and taxes you on what they produce. A SIPP is a different argument, and a better one — but it is an argument made on a return, not an automatic exclusion.

So the usual shape of this problem is not fraud and not really neglect. It is someone who filed every US return honestly and never thought to mention an account their home country had told them in writing was tax-free.

SDOP is the right door only if you are in the right room

The streamlined procedures have two tracks, and which one you may use is not a choice. It turns on a non-residency requirement: for a US citizen or lawful permanent resident, the IRS requires that in one or more of the most recent 3 years for which the return due date has passed, you had no US abode and were physically outside the United States for at least 330 full days. Both limbs, in the same year. Someone living and working in the United States fails that comfortably, which puts them on the domestic track — the track that carries a penalty.

A domestic submission is amended returns for the most recent 3 years for which the due date has passed, "together with all required information returns"; delinquent FBARs for the most recent 6 years; a signed Form 14654 certifying non-willfulness; the tax and interest; and a Title 26 miscellaneous offshore penalty of 5% of the highest aggregate balance or value of the assets in its base.

One line on that page decides eligibility for a great many people in this position, and it is easy to read past: "You may not file delinquent income tax returns (including Form 1040, U.S. Individual Income Tax Return) using these procedures." The domestic track amends returns you have already filed. If you never filed at all for one of those years, this door is shut and a different route has to be found. Our explainer on the Streamlined Domestic Offshore Procedure sets out the full mechanics; what follows is only what the two UK wrappers add to them.

What an ISA does to the submission

An ISA brings a form most people have never heard of, and closes an election most people assume is available.

The funds are the issue, not the account. A UK open-ended investment company, unit trust or investment trust is a foreign corporation, and the Form 8621 instructions make it a passive foreign investment company if it meets either of two tests: an income test, on the share of its gross income for the year that is passive income, or an asset test, on the average percentage of its assets held to produce passive income. A fund that holds shares and bonds and distributes the income meets that description without trying. Generally "a U.S. person that is a direct or indirect shareholder of a PFIC must file Form 8621" — one per fund, per year, which is why a single diversified ISA can generate a stack of them.

Form 8621 is not optional in a streamlined submission, and you do not have to infer that. It appears in the IRS's own parenthetical list of the information returns that must accompany the amended returns: "(e.g., Forms 3520, 3520-A, 5471, 5472, 8938, 926, and 8621)".

There is a carve-out, and it is worth knowing precisely because it looks like it ought to help. A US person who holds PFIC stock through certain tax-exempt vehicles is not treated as a shareholder at all. But the list is a list of US-law accounts: organizations and accounts exempt under section 501(a), section 403(b) and 457(b) plans, individual retirement plans as defined in section 7701(a)(37), section 529, 530 and 529A programs, and certain state colleges. A UK ISA is not on it. Being tax-exempt in Britain does not put an account on a list of accounts that are tax-exempt in America.

Then the hard part. PFIC holders can usually choose a more rational regime — a qualified electing fund election, or a mark-to-market election — instead of the punitive default. Both have deadlines. The mark-to-market election "must be made on or before the due date (including extensions) of the U.S. person's income tax return", and a QEF election is likewise made by the due date including extensions for the first year it applies, with a retroactive election allowed "only if" narrow conditions are met. A catch-up filed years later is not a timely return. So an ISA cleaned up through a streamlined submission generally arrives in the default section 1291 regime — distributions and gains above the ordinary level allocated back across your holding period, with an interest charge — rather than the regime most readers assume they can opt into. A de minimis exception to filing Form 8621 also exists below a stated value of PFIC stock; whether you are under it is a figure to check against the current instructions, not to assume.

That is a reason to have the funds analysed before the amended returns are drafted — the PFIC computation drives the tax, which drives the interest — not a reason to sell in a panic. Our guides to PFIC tax rules for US investors abroad and the QEF and mark-to-market elections on Form 8621 go further into the mechanics.

What a SIPP does to the submission

A SIPP is a reportable account on the same basis as the ISA: on the FBAR, and on Form 8938 at its thresholds. That part is not controversial and is not improved by the pension label.

What is contested is the taxing side. Whether the US–UK treaty defers US tax on growth inside the fund, on what conditions and with what disclosure, is a position taken on a return. It depends on the scheme, the contributions, and what was claimed or not claimed in the years being amended — and the public guidance openly disagrees with itself. A streamlined submission is often where a missed election is put right, and the IRS's domestic instructions contemplate retirement-plan deferral election requests being included where applicable. Our article on an unreported foreign pension in an SDOP deals with that election in detail.

The trust-form question is separate again. Some advisers treat a SIPP as a foreign grantor trust requiring Forms 3520 and 3520-A; others rely on a revenue procedure exempting certain tax-favored foreign retirement trusts from those forms, subject to conditions including contribution limits and the individual's own filing compliance. Whether a particular scheme satisfies them is a determination on its facts, and the wrong answer either way is expensive: an unnecessary 3520-A is noise, a missing one is a penalty.

And if the SIPP holds UK funds — most self-invested ones do — the PFIC analysis above may reach inside it too, on the same look-through logic. See US tax on UK pensions and SIPPs for the standing treatment.

The penalty limb that catches an ISA you did disclose

This is the detail that surprises people most, and it is written plainly in the IRS's own terms. An asset goes into the 5% penalty base in three situations: if it should have been but was not reported on an FBAR for that year; if it should have been but was not reported on a Form 8938 for that year; or if "the asset was properly reported for that year, but gross income in respect of the asset was not reported in that year".

Read that third limb against the typical ISA. Plenty of people listed the ISA on their FBAR year after year — it was on the bank letter, so it went on the form — and never reported a penny of what it earned, because the letter also said it was tax-free. The account was disclosed. The income was not. The asset is in the base.

The base itself is the highest aggregate: year-end balances and values are aggregated for each year across the covered periods, and the highest of those yearly totals is what the 5% is charged on. A long-grown SIPP can therefore matter more to the penalty than the ISA that caused the problem. We cover the arithmetic in how the SDOP penalty base is measured and the payment mechanics in how to pay the SDOP 5% penalty.

"But it was tax-free at home" — is that non-willful?

Form 14654 asks for a narrative, not a formula, and it is signed under penalty of perjury. "My home country told me it was tax-free" is a genuine and commonly accepted part of such a narrative. It is not, by itself, the whole of one. The facts that matter are what you were told and by whom, what your preparer was shown and asked, whether a foreign-accounts question on a return was answered no, and what happened when you found out. Write the history you can document, not the history that sounds best. What non-willful really means goes through the standard.

The order to do this in

1. Fix which years are in scope — and confirm a return was actually filed for each income tax year, because the domestic track cannot be used to file a late one.

2. Get full statements for both accounts, down to every fund line, distribution and switch. Fund-level detail is what the PFIC work needs; an account valuation is not enough.

3. Classify the funds, and settle the SIPP's treaty and trust-form position, before anything is drafted.

4. Build the penalty base from year-end values across both covered periods, including accounts that were disclosed but whose income was not reported.

5. Draft the narrative last, and have it reviewed before it is signed.

Where we fit

We prepare these submissions end to end: the amended returns, the Form 8621s fund by fund, the FBARs, the penalty computation and the Form 14654 narrative, with the UK documents read as UK documents rather than guessed at. Every return and every form is reviewed and signed off by a licensed professional — an IRS Enrolled Agent who is also ACCA-qualified — so the US filings and the UK position are looked at by one person rather than two who never speak.

You can see what this work costs, book a consultation to scope your own years, or model the numbers first with our calculators. We do not file on your behalf: you sign and submit, once a licensed professional has reviewed what you are signing.