Specialist US UK Tax Services: Closing Unfiled UK Years

If you left the UK with Self Assessment returns unfiled and never made the matching US information returns for those years, you are looking at two separate clean-ups that have to be run in one sequence. Our Specialist US UK tax services close the UK years and the US years together, in the right order.

This guide is written for a specific person: the American who spent several years in London, came home, and discovered afterwards that neither side was finished with them. At Jungle Tax this is the single most common backward-looking engagement we take on, and it is materially different from the standard expat catch-up. You are no longer resident in the UK, so the UK-side leverage and the UK-side records are both harder to reach. You are now resident in the US, so at least one of the IRS concessions you have read about may already be slipping away from you. Both of those facts are governed by clocks that started running the day you boarded the plane.

Why leaving the UK did not close your UK filing obligations

Departure is an administrative event, not a legal severance. HMRC does not automatically cancel anything when you stop being resident. Three things typically survive a move back to the States, and they survive independently of each other.

Did HMRC actually require a return for those years?

This is the first question, and getting it wrong in either direction is expensive. There are two distinct UK failures and they carry completely different consequences:

• Failure to file. If HMRC issued you a notice to file for a tax year and you did not submit the return, fixed late-filing penalties accrue automatically whether or not any tax was due. The standard escalation is an initial fixed penalty, then daily penalties once the return is three months late up to a capped total, then further penalties at six and twelve months calculated as the greater of a fixed amount or a percentage of the tax due. Where the unpaid tax relates to an offshore matter, the twelve-month penalty can be uplifted substantially.
• Failure to notify. If HMRC never issued a notice for a year, you had no return obligation under it. Instead you had an obligation to notify chargeability by the statutory date following the end of the tax year. Penalties here are behaviour-based and calculated as a percentage of the potential lost revenue, which means that a year with no UK tax to pay generates no penalty at all.

Most returnees assume they are in the first category for every open year. Frequently they are not. HMRC often stops issuing notices a year or two after a taxpayer's record goes quiet, so the tail years may be notify-only years with a nil liability and therefore nil exposure. Establishing which years carry a live notice, before you disclose anything, is the difference between a clean-up that costs a few hundred pounds in penalties and one that costs several thousand. HMRC also has a statutory power to withdraw a notice to file where a return was not in fact required, which can remove the associated late-filing penalties, though it is time-limited and applied at HMRC's discretion.

What was still due after you left

Non-residence narrows the UK tax base; it does not empty it. The items that most often remained live for our clients after departure are:

• The departure year itself. Split-year treatment under the Statutory Residence Test is not automatic in the administrative sense. Where you are in Self Assessment for the year of departure, you claim it on the residence pages of the return. If the return was never filed, the claim was never made, and HMRC's default position is that you were UK resident for the whole year with worldwide income in scope.
• UK rental income. If you kept the London flat and let it, you remained within the Non-Resident Landlord Scheme and within Self Assessment. Letting agents who did not hold approval to pay gross should have been withholding basic-rate tax, and often were not.
• UK property disposals. A sale of UK residential property by a non-resident requires a standalone capital gains return and payment within a short statutory window after completion, separate from and in addition to the annual return. Selling the flat after you moved home is one of the most commonly missed UK filings we see.
• UK workdays. Post-departure business trips back to a UK employer or a UK subsidiary can generate UK employment income that PAYE never captured.
• Temporary non-residence. If your absence from the UK turns out to be short and you return within the statutory period, certain income and gains realised while away are pulled back into charge in the year of return. This matters if the US move might not be permanent.

The eligibility clock nobody told you was running

Here is the point that generalist streamlined guides almost universally miss, because they are written for people still living abroad. The IRS operates two streamlined tracks, and which one you get is determined by a residency test measured against the three most recent tax years for which the return due date (including any properly applied-for extension) has passed.

The favourable track, the Streamlined Foreign Offshore Procedure, requires that in at least one of those three years you had no US abode and were physically outside the United States for at least 330 full days. It carries no miscellaneous offshore penalty. The domestic track carries a penalty calculated on the highest aggregate value of your unreported foreign financial assets.

A returnee frequently still qualifies for the foreign track for a limited period after coming home, because a qualifying overseas year is still inside the three-year testing window. Every 15 April, one year rolls off the back of that window. Sooner or later the last qualifying year drops out, and the concession is gone permanently. We have taken calls from people who spent eighteen months deciding whether to act and, in doing so, converted a zero-penalty filing into a five-figure one. If you left the UK recently, the single most time-critical thing you can do is establish today whether a 330-day year is still in your window and how many filing seasons it has left.

There is a second trap layered underneath. The domestic track is not a universal fallback. It is only available to taxpayers who actually filed a US return for each of the three most recent years, and it is delivered through amended returns. A person who filed nothing at all while in London and nothing since cannot simply drop into the domestic procedure once the foreign window closes. They are pushed towards delinquent filing with a reasonable-cause position, or, where willfulness is genuinely in question, the IRS Criminal Investigation Voluntary Disclosure Practice, which is a different and far heavier process.

US route selection for a returnee

Your position	Likely route	The condition that decides it
Never filed US returns; a 330-day year is still in the three-year window	Streamlined Foreign Offshore	No US abode plus 330 days outside the US in a qualifying year; non-willful conduct
Filed US returns but omitted UK accounts, ISA income or rental profits	Streamlined Domestic Offshore	Original returns already on file for the three years; delivered as amended returns; penalty applies
Reported and paid tax on all income, but never filed FBARs	Delinquent FBAR Submission Procedures	No unreported income and not under examination
Income reported, but Forms 5471, 8621, 3520 or 8938 missing	Delinquent International Information Return Procedures	A credible reasonable-cause statement attached to each late form
Conduct was not plausibly non-willful	Voluntary Disclosure Practice	Pre-clearance from IRS Criminal Investigation; a penalty regime, not an amnesty

Whatever the route, one thing is common to all of them: it closes the moment the IRS opens a civil examination of any year, for any reason. Eligibility is not something you can hold in reserve. Full detail on how we scope and deliver these packages is on our IRS streamlined filing page, and the current procedural terms are published by the IRS at irs.gov, with the separate foreign and domestic conditions set out at the residing-outside-the-US page.

The two clean-ups compared

	United States (IRS)	United Kingdom (HMRC)
Principal route	Streamlined Filing Compliance Procedures, foreign or domestic track	Worldwide Disclosure Facility, notified through the Digital Disclosure Service
Years of returns	Three most recent years for which the due date has passed	Determined by behaviour: broadly four years for innocent error, six for careless, twelve where an offshore matter is involved and twenty for deliberate conduct
Account reporting look-back	Six years of FBARs	No separate account report; offshore assets are disclosed within the liability computation
Penalty if you self-correct properly	Nil on the foreign track; a percentage of highest aggregate asset value on the domestic track	A reduced percentage of the tax, negotiated by reference to behaviour, disclosure quality and territory category
Penalty if they reach you first	Failure-to-file, accuracy, information-return and FBAR penalties, some assessed per form per year	Prompted-disclosure penalty ranges, materially higher than unprompted, plus offshore uplifts
Basis period	Calendar year	6 April to 5 April
Currency	US dollars; year-end Treasury rates for FBAR	Pounds sterling
What you sign	A penalties-of-perjury narrative certifying non-willfulness	A disclosure and a formal offer, with a behaviour characterisation you have chosen
Concession lost when	The IRS opens any civil examination	HMRC contacts you first, converting the disclosure to prompted

Which comes first, HMRC or the IRS?

Clients expect a simple answer. The honest one is that the calendar is driven by the US and the arithmetic is driven by the UK, and the two have to be managed against each other rather than in series.

The arithmetic runs UK-first because your US liability for the London years depends on the foreign tax credit for UK tax on the same income, and you cannot compute that credit until you know what the UK liability actually is. Filing a streamlined package with a guessed UK number produces a certification you may have to walk back.

The calendar runs US-first because the streamlined foreign eligibility window is the only element in the whole exercise with a hard expiry date. HMRC disclosure timescales are elastic; the 330-day window is not. Where the window is closing inside a filing season, we prepare the UK computations to a defensible provisional standard, file the US package on that basis, then true up.

The mechanism that makes truing-up possible is the extended limitation period for refund claims attributable to foreign taxes. Ordinary refund claims die after roughly three years. Claims driven by foreign tax carry a much longer window, running to a decade from the due date of the return for the year concerned. That is why a UK settlement finalised in 2026 can still be credited back against a US return for a London year several years earlier. Very few generalist advisers use it, and it is often the single largest cash item in the engagement.

Paid or accrued: the election that quietly decides the outcome

Foreign tax credits can be claimed on a cash basis, in the year the UK tax is actually paid, or on an accrual basis, matched to the year the income arose. For a returnee this is not a technicality. If you settle four years of UK tax in a single payment in 2026, a cash-basis claim dumps the entire credit into a year in which you may have no UK-source income at all, generating credits in the wrong basket that largely go to waste. The accrual basis puts each year's UK tax against that year's UK income, which is almost always the right answer, but the election is binding on all future years once made. It must be modelled, not defaulted into.

The narratives must agree

You will sign a non-willfulness certification for the IRS and characterise your behaviour for HMRC. Those two documents describe the same facts to two authorities that exchange information with each other under the exchange of information article of the US-UK double tax treaty. A US certification saying you misunderstood your obligations sits badly alongside a UK disclosure conceding deliberate behaviour, and vice versa. Drafting them as one consistent account of what happened, prepared at the same time by the same team, is the most important professional judgement in the whole engagement. It is also the reason we do not recommend appointing separate unconnected firms on each side.

Reconstructing the UK period from a US address

This is the practical work, and it is the part clients underestimate by an order of magnitude. Evidence that would have taken an afternoon to assemble while you still lived in Clapham can take three months to recover from Connecticut.

What to request, and from whom

• UK banks and building societies. Most will close a current account once you have no UK address, and many will not reopen digital access afterwards. Records are typically retained for a limited number of years after closure, and retrieval is often chargeable. A subject access request under UK data protection law is a free and enforceable route to your own transaction history, and it works even where the commercial retrieval desk says no.
• HMRC itself. If you cannot pass Government Gateway identity verification from abroad, which is common once your UK phone number and UK credit footprint have lapsed, appoint a UK agent through the standard authorisation form. Your agent can then obtain your Self Assessment record, the list of years for which notices to file were issued, statements of account and PAYE history. That single step usually resolves the "which years actually count" question in days.
• Former employers. Ask for P60s, the final P45, P11Ds and payslips. Employers hold payroll records for a limited period and the counterparty may since have been acquired, merged or dissolved.
• Pension providers. Annual statements, contribution histories and, critically, fund-level holdings. You need the underlying fund detail, not just the wrapper valuation, to take a defensible US position on the arrangement.
• ISA and investment platform managers. Full transaction history, not annual summaries. Valuations alone will not support the analysis of collective investments.
• Letting agents and managing agents. Rental statements, service charge and repair schedules, and any Non-Resident Landlord Scheme paperwork.
• Land Registry. Title copies are inexpensive, instantly available online and provide unimpeachable evidence of acquisition and disposal dates for a UK property.

The records that genuinely disappear

Bank statements and payslips can usually be recovered with persistence. What does not come back is the contemporaneous evidence of your movements and intentions: boarding passes, calendar entries, the tenancy agreement in the loft, the letter from the employer confirming the transfer date. Day counts under the Statutory Residence Test, and the 330-day count for the IRS, both depend on this material, and HMRC's own guidance on the test is unambiguous that the burden of proof is yours. HMRC publishes the detailed test and split-year cases in RDR3. Before anything else, export your old calendars, download your airline account histories and pull your passport stamps into a dated schedule. That schedule is the foundation of both filings.

The UK disclosure mechanics

For UK liabilities connected to an offshore matter, and for a US-resident former UK taxpayer almost everything now qualifies as offshore, the route is the Worldwide Disclosure Facility. You notify HMRC through the Digital Disclosure Service, receive a disclosure reference number, and then have a defined window, ordinarily ninety days with the possibility of an extension in complex cases, to submit the full disclosure and make an offer. Non-residents can use it. HMRC's own guidance is at gov.uk.

Three things determine the penalty outcome. First, behaviour: innocent error, careless, or deliberate, which also sets how many years HMRC can assess. Second, whether the disclosure is unprompted or prompted, and the gap between those two ranges is large enough on its own to justify moving quickly. Third, the offshore territory category, which for a US-connected disclosure can carry a loading.

Two points of leverage are routinely left on the table. Non-residents benefit from a limitation on UK tax charged on certain UK savings and dividend income, which in the right circumstances reduces the UK liability for the post-departure years to nil and, with it, the penalty base. And the assessment time limits work in your favour where behaviour was genuinely innocent: the shortest window is four years, and disclosing years HMRC can no longer assess is a gift you are not required to make. Our UK tax services team scopes both of these before any disclosure is notified.

The US information returns that were missed for the UK years

Tax on the income is usually the smaller half of the problem. The information returns are where the exposure concentrates, because several carry penalties assessed per form, per year, regardless of whether any tax was due.

• FBAR. Every UK account you held or had signature authority over, aggregated. Current accounts, savings, ISAs, pension arrangements in many cases, and employer accounts you could sign on. You can model exposure with our FBAR penalty calculator.
• Form 8938. Note that the reporting thresholds for the back years are the higher thresholds that applied to you as a US person living abroad in those years, not the lower thresholds that apply to you now that you are home. Applying today's thresholds to old years overstates the failure.
• Form 8621. UK collective investments, whether held inside an ISA or a general investment account, are generally passive foreign investment companies for US purposes. The ISA wrapper is invisible to the IRS. This is usually the most labour-intensive part of a London clean-up and the reason full transaction histories matter so much.
• Forms 5471 and 8858. The UK limited company you set up for consulting, even one long dormant, and any shareholding or directorship in a UK company. Penalties here start at a substantial fixed amount per form per year.
• Forms 3520 and 3520-A. Certain UK trust and settlement arrangements, and some non-pension employer schemes.
• Treaty positions. Where the US-UK treaty is being relied on for a pension arrangement, the position should be documented and, where required, disclosed on the appropriate form rather than assumed.

A workable sequence

The order we run for a returnee, compressed:

• Weeks 1 to 2. Establish the 330-day position and how many filing seasons the foreign streamlined window has left. Appoint a UK agent and pull the HMRC record to identify which years carry a live notice to file. Build the day-count schedule.
• Weeks 2 to 8. Issue every records request in parallel, not in series. Data protection requests to banks and platforms, employer payroll requests, provider statements, Land Registry titles.
• Weeks 6 to 12. Determine residence status year by year, compute the UK liability including the non-resident limitations, and settle the behaviour characterisation. Draft both narratives together.
• Weeks 10 to 14. Notify HMRC and obtain a disclosure reference number, starting the disclosure window only once the computations are substantially complete. Simultaneously finalise the US package, converting to calendar years and modelling the credit basis election.
• Filing. Submit the streamlined package with the certification, and the UK disclosure and offer. Where the US window is closing first, file the US side on provisional UK figures and revisit under the extended foreign tax refund period.
• Closing the file. Ask HMRC to stop issuing future notices where none are needed, confirm your non-resident status on the record, deregister from the Non-Resident Landlord Scheme if the property has gone, and retain the full evidence file. Both authorities can revisit, and the file is your defence.

What waiting actually costs

Four things deteriorate simultaneously, and none of them recover. The streamlined foreign window narrows by one year every April. UK late-filing penalties continue to accrue on any year with a live notice, and interest runs on the tax throughout. Records become progressively harder and more expensive to obtain as accounts close, employers restructure and retention periods expire. And the disclosure remains unprompted only until HMRC or the IRS makes contact first, at which point the concessions that make this affordable simply stop being available. Every one of those is a function of elapsed time rather than complexity, which is why the clean-up almost always costs less today than it will next spring.

If you have unfiled UK years behind you and a US filing history that never reflected them, we can tell you within one conversation which IRS route is still open to you, how long it stays open, and which UK years genuinely need to be disclosed. Our US-UK tax accountants handle both sides in-house, so the two narratives are written once and agree with each other. To discuss your position in confidence, contact our cross-border team for a private consultation. Nothing is filed, notified or disclosed until you have seen the full picture and instructed us to proceed.