Can I use IRS Streamlined Filing if my conduct was willful?

No. The streamlined procedures require a certification, signed under penalties of perjury, that the failure to report income, pay tax and file required information returns including FBARs was due to non-willful conduct. The IRS defines non-willful conduct as conduct due to negligence, inadvertence or mistake, or the result of a good faith misunderstanding of the requirements of the law. Where conduct was willful, the IRS directs taxpayers to its Criminal Investigation Voluntary Disclosure Practice instead.

How many years does each route cover?

The Streamlined Foreign Offshore Procedures cover the three most recent years for which the US tax return due date has passed and the six most recent years for which the FBAR due date has passed, so the older three years carry FBARs only. The Voluntary Disclosure Practice disclosure period generally includes the most recent six years of amended or delinquent returns and reports, and the IRS may allow a cooperative taxpayer to expand that period with its consent.

Does a voluntary disclosure protect me from prosecution?

Not automatically. The IRS states that the Voluntary Disclosure Practice will not automatically guarantee immunity from prosecution, but that a voluntary disclosure may result in prosecution not being recommended. It is a cooperative route, not a guarantee. It also requires cooperation with the examiner and payment in full, or a full-pay instalment agreement, for the tax, interest and applicable penalties. Withdrawing cooperation can result in all applicable penalties being applied.

What penalties apply under the Streamlined Foreign Offshore Procedures?

A compliant Streamlined Foreign Offshore filer is not subject to failure-to-file or failure-to-pay penalties, accuracy-related penalties, information return penalties, or FBAR penalties. Tax and interest on the three corrected return years remain payable. There is no miscellaneous offshore penalty on the foreign branch. The domestic branch, used by taxpayers who fail the non-residency test, carries a 5 percent Title 26 miscellaneous offshore penalty on the penalty base instead.

Can I still use either route if the IRS has already contacted me?

Generally no. If the IRS has initiated a civil examination of your returns for any taxable year, regardless of whether it relates to undisclosed foreign financial assets, you are ineligible for the streamlined procedures, and a taxpayer under IRS Criminal Investigation is also ineligible. A voluntary disclosure is timely only if received before the IRS has begun a civil examination or criminal investigation, before it has received third-party information about the noncompliance, and before it has obtained information from a criminal enforcement action.

Will UK banks report me to the IRS before I file?

They report to HMRC, which shares the information. HMRC guidance confirms that the agreement between the UK and the USA requires UK financial institutions to report to HMRC on US customers holding accounts with them, and that HMRC shares this information with the relevant countries. This flow is automatic and annual, so it does not depend on your decision to disclose. It is also why third-party information reaching the IRS can defeat the timeliness of a voluntary disclosure.

IRS Streamlined Filing vs Voluntary Disclosure

IRS Streamlined Filing and the IRS Criminal Investigation Voluntary Disclosure Practice are not two speeds of the same programme, and the choice between them is not a matter of how much tax is at stake or how many years are missing. They are separated by a single question of fact: whether the failure to report was non-willful. The streamlined procedures at irs.gov/individuals/international-taxpayers/streamlined-filing-compliance-procedures are open only to taxpayers who certify non-willfulness. The Voluntary Disclosure Practice at irs.gov/compliance/criminal-investigation/irs-criminal-investigation-voluntary-disclosure-practice exists for the opposite population: the IRS describes a voluntary disclosure as a truthful, timely and complete disclosure of willful noncompliance.

For a UK-resident investor or business owner the practical consequences of that split are stark. A qualifying Streamlined Foreign Offshore filing covers three years of returns and six years of FBARs and carries no failure-to-file penalty, no failure-to-pay penalty, no accuracy-related penalty, no information return penalty and no FBAR penalty. A voluntary disclosure generally runs to the most recent six years, is examined rather than simply processed, and carries a civil fraud penalty in at least one year plus FBAR violations treated as willful. One route ends with a filing. The other ends with an examination that you have invited and agreed to fund.

The part of this decision that published guidance handles worst is the risk sitting inside the streamlined route itself. The non-willfulness certification is signed under penalties of perjury. Where the facts do not support it, the certification is not a cheaper alternative to a voluntary disclosure; it is a fresh, dated, signed exposure stacked on top of the original one. In the returns we prepare for UK-based clients, that is the point where a file most often needs to slow down, and it is the point this guide is built around.

What is the difference between IRS Streamlined Filing and the Voluntary Disclosure Practice?

IRS Streamlined Filing is a compliance procedure. You assemble a package, you certify eligibility and non-willfulness, you file, and if the package is complete and the certification holds, the penalty relief described on the IRS pages applies by operation of the procedure. There is no application, no acceptance letter and no gatekeeper deciding whether you may enter. The IRS states that returns submitted under either streamlined branch will not be subject to IRS audit automatically, but that they may be selected for audit under the existing audit selection processes applicable to any US tax return.

The Voluntary Disclosure Practice is an application to IRS Criminal Investigation followed by a civil examination. You request preclearance, you are either cleared or not, you then submit a detailed narrative, you are either preliminarily accepted or not, and a civil examiner then works the case to a resolution. The IRS is explicit that the practice will not automatically guarantee immunity from prosecution, but that a voluntary disclosure may result in prosecution not being recommended. That is the whole product: not a penalty discount, but a documented, cooperative path away from a criminal referral.

The IRS itself signposts the split. The Voluntary Disclosure Practice page states that taxpayers who made a non-willful error in filing their taxes should consider options that include amended returns or delinquent returns, and it describes willfulness as the intentional, purposeful, deliberate act to hide income or assets. It also carries separate telephone lines for the two populations: 904-661-3350 for procedural questions on the Voluntary Disclosure Practice, and 267-466-0020 for the streamlined filing compliance procedures.

Set out side by side, the structural differences that matter to a UK filer are these:

Entry. Streamlined is self-executing: you file. The Voluntary Disclosure Practice requires preclearance from IRS Criminal Investigation before you may proceed.
What you assert. Streamlined requires a certification of non-willful conduct. A voluntary disclosure requires a narrative describing the noncompliance in full, including unfavourable facts.
Covered years. Streamlined covers the three most recent years for which the return due date has passed and the six most recent years for which the FBAR due date has passed. The voluntary disclosure period generally includes the most recent six years of amended or delinquent returns and reports.
Penalties. A qualifying Streamlined Foreign Offshore filing carries none of the standard penalties. A voluntary disclosure carries a civil fraud penalty in at least one year and FBAR penalties applied on a willful basis.
Criminal exposure. Streamlined offers no protection from prosecution and never claimed to. The Voluntary Disclosure Practice is the only route the IRS operates that is designed to address it, and even then without a guarantee.
What ends it. Both routes close once the IRS has already started: a civil examination or a criminal investigation blocks streamlined, and defeats the timeliness of a voluntary disclosure.

How does the IRS define non-willful conduct?

Non-willful conduct is conduct that is due to negligence, inadvertence, or mistake, or conduct that is the result of a good faith misunderstanding of the requirements of the law. That single sentence, published on the streamlined filing compliance procedures page at irs.gov, is the entire statutory-style definition you are certifying against, and every word of it is doing work.

Negligence, inadvertence and mistake describe a state of mind in which the obligation was not brought to conscious attention. A good faith misunderstanding of the requirements of the law describes something different: the obligation was considered, and the conclusion reached about it was wrong but honestly held. A UK-resident US citizen who genuinely believed that a stocks and shares ISA held with a UK provider was not a foreign financial account because it felt domestic to him sits in the second category. Someone who was told by a UK accountant that US filings were required, decided the risk of doing nothing was acceptable, and carried on, sits in neither.

Willfulness in this area is not restricted to a documented intention to defraud. It extends to conduct the courts have described as reckless disregard of a known or obvious obligation, and the most commonly cited evidence of it is a signature on a return. Schedule B (Form 1040) Part III line 7a asks, in the 2025 wording, whether at any time during the year you had a financial interest in or signature authority over a financial account, such as a bank account, securities account or brokerage account, located in a foreign country, and it carries a caution that failure to file FinCEN Form 114 where required may result in substantial penalties. A person with a Barclays current account, a Hargreaves Lansdown dealing account and a Coutts deposit who signed a return answering no to that question has a difficult conversation ahead, and the difficulty grows with every year the answer was repeated.

What does the non-willfulness certification actually commit you to?

A UK-resident filer using the Streamlined Foreign Offshore Procedures signs Form 14653, the Certification by US Person Residing Outside of the United States. A filer who fails the non-residency test and uses the domestic branch signs Form 14654 instead. Both are signed under penalties of perjury, and both require the same three assertions: that you are eligible for the procedures, that all required FBARs have been filed, and that the failure to file tax returns, report all income, pay all tax and submit all required information returns, including FBARs, resulted from non-willful conduct.

The certification is not a tick-box. It requires a narrative of the specific reasons for the failure, and a bare statement that you did not know is the weakest version of that narrative available. What carries weight is a factual account with dates, documents and decisions in it: when you moved to the UK, what you understood your position to be and why, who advised you and on what, when the position changed, and what you did once it did. Where reliance on a professional is part of the story, the account has to name the reliance honestly, including where the adviser was a UK-only practice with no US remit.

Three mechanical points are easy to miss and both waste and undermine an otherwise sound package. First, the words Streamlined Foreign Offshore must be written in red ink at the top of the first page of each delinquent or amended tax return and at the top of each information return. Second, an original signed statement must accompany the submission, with a copy attached to each return. Third, the FBARs are not part of the paper package at all: they go through the FinCEN BSA E-Filing System at bsaefiling.fincen.treas.gov, selecting Other as the reason for late filing and entering Streamlined Filing Compliance Procedures in the explanation box.

Which years does each route cover?

The streamlined covered periods are fixed and asymmetric, which is the single most common source of confusion in the packages we review. For the Streamlined Foreign Offshore Procedures at irs.gov/individuals/international-taxpayers/us-taxpayers-residing-outside-the-united-states, the return period is the three most recent years for which the US tax return due date, or properly applied for extended due date, has passed, filed as delinquent Forms 1040 or amended Forms 1040-X as the case requires, together with any required information returns such as Forms 3520, 5471 and 8938. The FBAR period is the six most recent years for which the FBAR due date has passed.

The three-year window sits inside the six-year window, so the three most recent years carry both a return and an FBAR obligation while the three older years carry an FBAR obligation only. Nothing in the procedure asks you to file returns for the older three. That asymmetry is deliberate and it is also why the Streamlined Domestic Offshore penalty base, at 5 percent of the highest aggregate balance or value of the foreign financial assets subject to the penalty, is computed across both periods rather than one.

The Voluntary Disclosure Practice is different in kind. The IRS states that the disclosure period generally includes the most recent six years of amended or delinquent returns and reports, and the Internal Revenue Manual material at irs.gov/irm/part4/irm_04-063-003r records that the practice generally requires civil examinations of the most recent six tax years for which the due date has already passed. It also records that, with the IRS's consent, cooperative taxpayers may be allowed to expand the disclosure period. The word generally is load-bearing: the six-year figure is a starting position for an examination, not a boundary written into the taxpayer's favour.

For a UK filer there is a separate deadline that runs regardless of which route is chosen. The FBAR is an annual report due 15 April following the calendar year reported, with an automatic extension to 15 October, and it is required where the aggregate value of the foreign financial accounts exceeded 10,000 US dollars at any time during the calendar year, as set out at irs.gov/businesses/small-businesses-self-employed/report-of-foreign-bank-and-financial-accounts-fbar. Aggregate is the operative word. A UK household with a current account, a savings account, an offset mortgage account, a dealing account and a workplace share plan account can pass that threshold on the sum of small balances while no single account looks remotely relevant.

What penalties apply under each route?

A qualifying Streamlined Foreign Offshore filing is the most favourable outcome the IRS publishes for a taxpayer with unreported foreign accounts. The IRS states that compliant filers will not be subject to failure-to-file and failure-to-pay penalties, accuracy-related penalties, information return penalties, or FBAR penalties. Tax and interest on the corrected returns remain payable. There is no miscellaneous offshore penalty on the foreign branch at all, which is why the non-residency test matters so much in money terms: a filer who satisfies it pays no penalty component, and a filer who does not falls into the domestic branch at irs.gov/individuals/international-taxpayers/us-taxpayers-residing-in-the-united-states and its 5 percent charge on the penalty base.

The non-residency test for a US citizen or lawful permanent resident is that, in any one or more of the most recent three years for which the US tax return due date has passed, the individual did not have a US abode and was physically outside the United States for at least 330 full days. A non-citizen who is not a lawful permanent resident is tested instead against the substantial presence test. Abode and days are separate hurdles, and a UK-resident banker who keeps a New York apartment available year-round can clear 330 days and still fail on abode.

The voluntary disclosure penalty framework is built on the opposite premise. The Internal Revenue Manual material records that a civil fraud penalty or fraudulent failure to file penalty, under IRC section 6663 or IRC section 6651(f) respectively, will apply to at least one year of every voluntary disclosure, and that the penalty should be asserted in the tax year with the highest tax deficiency. Application of that single fraud penalty is in lieu of accuracy-related penalties under section 6662 and delinquency penalties under sections 6651(a)(1) and 6651(a)(2). For cases involving FBAR non-compliance, FBAR violations are treated as willful and penalties apply accordingly, with the civil FBAR penalty maximums in Title 31 adjusted annually for inflation.

That structure rewards cooperation and punishes its absence sharply. The IRS requires participants to cooperate in determining the correct tax liability, to provide requested documents and information to the examiner, and to pay in full or secure a full-pay instalment agreement for the tax, interest and any applicable penalties owed. The manual material records that where a taxpayer does not cooperate and revocation procedures are followed, all applicable penalties may be applied based on the facts and circumstances of the case. A voluntary disclosure entered and then obstructed is worse than no disclosure at all, because the disclosure has already handed over the narrative.

How does preclearance and Form 14457 work?

The Voluntary Disclosure Practice runs on Form 14457, the Voluntary Disclosure Practice Preclearance Request and Application, in two stages. Part I is a preclearance request submitted by fax to 844-253-5613. IRS Criminal Investigation then determines whether you are precleared to enter the practice. Preclearance establishes eligibility for the practice; it does not guarantee preliminary acceptance into it, and it is not a decision on the merits of anything.

Once a preclearance letter is received, Part II must be submitted electronically within 45 days. Part II is where the substance sits: a narrative, signed under penalties of perjury, setting out the specific facts that detail the complete story of the noncompliance. The IRS requires the narrative to address the taxpayer's personal and professional background and to provide the whole story with all favourable and unfavourable facts, including the entire history of noncompliance from its inception through to the present. Status enquiries on preclearance requests and preliminary acceptance go to IRS Criminal Investigation by email.

Two features of that design deserve a UK reader's attention. The first is the 45-day clock, which starts on a letter you cannot schedule and runs while you are trying to reconstruct sterling balances, UK broker statements and years of dividend vouchers. Reconstruction work is done before Part I goes in, not after preclearance arrives. The second is the character of the narrative itself. It is an unforced, signed, dated account of your own conduct delivered to the criminal enforcement arm of the IRS, and it is the reason the practice is never entered casually or without US counsel engaged from the outset.

The form has been under active scrutiny on exactly this point. The National Taxpayer Advocate, at taxpayeradvocate.irs.gov, reported that Form 14457 had required taxpayers to affirm under penalty of perjury that they were willful in their noncompliance, that the requirement created self-incrimination risk if participation were later denied or preliminary acceptance revoked, and that the IRS agreed to remove that willfulness checkbox in the next revision of the form. The underlying eligibility position has not changed, and the practice remains a route for willful noncompliance with legally sourced income, but the mechanics of what a taxpayer must sign have been moving. Check the current revision of the form rather than relying on any description of it, including this one.

Neither route is available once the IRS has started

This is the timing rule that quietly decides more cases than the willfulness analysis does. On the streamlined side, the IRS states that if it has initiated a civil examination of a taxpayer's returns for any taxable year, regardless of whether the examination relates to undisclosed foreign financial assets, the taxpayer will not be eligible to use the streamlined procedures. A taxpayer under criminal investigation by IRS Criminal Investigation is also ineligible. Note how wide the first limb is: an examination of an unrelated year on an unrelated issue closes the door.

On the voluntary disclosure side the equivalent concept is timeliness. A disclosure is timely only if it is received before the IRS has commenced a civil examination or criminal investigation, before the IRS has received information from a third party alerting it to the specific noncompliance, and before the IRS has acquired information directly related to the specific noncompliance from a criminal enforcement action such as a search warrant or grand jury subpoena.

The third-party limb is the one UK investors underestimate, and it is where the two jurisdictions meet. HMRC guidance at gov.uk/guidance/automatic-exchange-of-information-introduction records that the agreement between the UK and the USA requires UK financial institutions to report to HMRC on US customers that hold accounts with them, and that HMRC shares that information with the relevant countries. A UK bank, building society, insurer or investment platform that has identified a customer as a US person has already been reporting. The information flow is automatic, annual and outside the customer's control, and it does not wait for the customer to decide which route to take.

Why quiet disclosure is not a recognised route

Quiet disclosure, sometimes called soft disclosure, describes the practice of filing amended returns and late FBARs without entering any programme and hoping the correction passes unnoticed. It is not an IRS procedure. There is no page describing it, no form supporting it, no penalty relief attached to it and no acknowledgement that it has happened. It is simply a set of filings, and it is processed as filings are processed.

The IRS addresses the position of taxpayers who have already done this. The streamlined page states that taxpayers who have previously filed amended or delinquent returns outside a formal programme to address their foreign financial asset obligations may still participate in the streamlined procedures, but that any penalty assessments previously made with respect to those filings will not be abated. So a quiet disclosure does not permanently disqualify you from the streamlined route, but any damage it has already caused is locked in.

The reason to avoid it is not that it is prohibited but that it collects the disadvantages of both routes and the protections of neither. It gives no penalty relief, because relief comes from the procedure and no procedure has been used. It gives no protection from prosecution, because that comes only from the Voluntary Disclosure Practice. It does not stop the clock on timeliness, because the IRS is still free to open an examination. And it draws attention to precisely the years and accounts the taxpayer was hoping to move past, in a pattern that examiners recognise on sight: several years of amended returns, filed together, all adding foreign income, all unexplained.

The fact patterns that should make a UK reader pause before certifying

The honest framing that most published guidance avoids is this: the streamlined certification is not a formality that unlocks a better outcome, it is a sworn statement of fact, and a certification signed by someone whose facts do not support it is itself a serious exposure. It converts a historic reporting failure into a current, dated, signed document with your name on it. If the IRS later concludes the conduct was willful, it does not simply move you across to the other route; it holds a certification you provided voluntarily.

In UK files we prepare, these are the fact patterns that stop a streamlined package and send it to counsel for a willfulness opinion before anything is signed:

Schedule B line 7a answered no in a year when you knew you held UK accounts. The question is short, plain and on the face of a return you signed. Repetition across years compounds it.
A UK or US adviser told you that US returns or FBARs were required, and the advice was not acted on. Written advice ignored is the single most damaging document in this area.
You were asked by a UK bank, platform or provider to complete a self-certification of US status and answered inaccurately, or declined to respond and let an account be treated as non-US.
You moved funds or accounts after learning of the obligation: closing a UK account, transferring a portfolio to a different provider, changing a mailing address away from a US one, or restructuring holdings through a UK company.
You filed US returns for some years and not others, or reported some UK accounts on an FBAR and not others, in a pattern that tracks which balances were larger.
You told a preparer that you had no foreign accounts, or answered a preparer's organiser question in the negative, when you did.
You held an account with a UK institution specifically because of its treatment of US persons, and there is correspondence about it.
Income arose that was plainly taxable in the US on any view, such as UK dividends, interest or gains on a general investment account, and it was never mentioned to anyone preparing your US filings.

None of these items is automatically fatal. A single no on line 7a in a year when a preparer never raised foreign accounts, in a file that otherwise shows an honest misunderstanding, may sit comfortably inside a good faith misunderstanding of the requirements of the law. What matters is the whole file read as a stranger would read it. The test we apply before allowing a certification to be signed is simple: if an examiner had every document, every email and every calendar entry in the client's possession, would the account in the certification still be the obvious reading of the facts? If the answer requires effort, the answer is no.

The UK-specific evidence that tends to surface

A willfulness analysis for a UK-resident investor is not conducted on the taxpayer's memory. It is conducted on documents, and UK document trails in this area are unusually rich because the UK financial and professional services sector generates and retains a great deal of paper about client status and advice.

FATCA reporting by UK institutions is the first of these. Under the UK and US agreement described at gov.uk/guidance/automatic-exchange-of-information-introduction, UK banks, building societies, insurance companies and investment companies report to HMRC on US customers holding accounts with them, and HMRC passes that information on. The practical implication is that the institution had to reach a conclusion about your status, and it reached that conclusion using something: a self-certification you signed, a US place of birth on your file, a US address or telephone number, or a standing instruction to transfer funds to a US account. Whatever it used still exists in the institution's records, and it is obtainable.

UK professional advice on file is the second. Onboarding letters from UK accountants routinely carve out US tax work by name, which is helpful to a good faith narrative and unhelpful the moment the same letter shows the adviser told you to take separate US advice. Wealth managers and private banks record suitability and tax-status discussions. Employers running share plans issue US-person communications. Solicitors handling a property purchase or a company reorganisation ask about tax residence and citizenship. Any of these can become the document that decides whether the failure was inadvertent.

The third is the difference in privilege. Communications with a UK accountant do not attract legal professional privilege in the way communications with a solicitor do, and US privilege doctrines do not map neatly onto the UK position either. The working assumption in a cross-border willfulness review should be that correspondence with an accounting firm is discoverable. That is why the sequence matters: the willfulness question is examined under legal privilege first, and the accounting work of building returns and schedules follows the conclusion rather than preceding it.

A worked scenario: a UK-resident investor choosing between the routes

The following is an illustration built to show the decision mechanics, not a real client, and every figure in it is assumed rather than drawn from a case. Assume a US citizen who has lived in London for eleven years, has no US abode, and has been physically outside the United States for the whole of each of the last three years. She holds a UK current account, two savings accounts, a general investment account with a UK platform and a workplace share plan account. Aggregate balances exceeded the FBAR threshold in every year. She has filed no US returns and no FBARs since moving.

On facts one, she has never engaged a US preparer, was told by nobody that US filing continued after leaving, and has never signed a US return in the UK years, so line 7a has never been answered at all. Her UK accountant's engagement letter is silent on US matters. This is the ordinary streamlined case. She meets the non-residency test on both abode and the 330-day count, so she uses the foreign branch: three years of delinquent Forms 1040 with any required information returns, six years of FBARs through the BSA E-Filing System, Form 14653 with a narrative explaining what she understood and why, and Streamlined Foreign Offshore in red at the top of each return. Tax and interest are payable on the three corrected years. No failure-to-file, failure-to-pay, accuracy-related, information return or FBAR penalty applies, and there is no miscellaneous offshore penalty on the foreign branch.

On facts two, change one item. In year four she completed a self-certification for her UK platform stating she was not a US person, after a telephone call in which the platform explained that US persons faced additional reporting. She retained the platform's letter. Nothing else changes. The rest of the file still reads as an honest misunderstanding, but that single document is a considered, written, inaccurate statement about the exact status at issue, made after the obligation was flagged. The certification narrative would have to disclose it, and a certification that discloses it while asserting non-willfulness is asking the IRS to accept a reading the document does not support. This file goes to counsel before anything is signed, and preclearance under the Voluntary Disclosure Practice is on the table.

The point of the comparison is that the two files differ by one piece of paper, not by the amount of tax, the size of the balances or the number of missing years. Nothing about the money changed. What changed was the evidence about the state of mind, and that is the only variable the routes actually distinguish on.

The UK side of the same decision: WDF and Code of Practice 9

A UK-resident investor with a US problem frequently has a UK one alongside it, and HMRC operates a structurally similar pair of routes. The Worldwide Disclosure Facility at gov.uk/guidance/worldwide-disclosure-facility-make-a-disclosure is the route for disclosing a UK tax liability relating wholly or in part to an offshore issue. It runs on a notification followed by a disclosure reference number, after which there are 90 days to gather the information and complete the disclosure, with a further period available in complex cases. Crucially, HMRC states that you may still be liable to criminal prosecution and that it reserves complete discretion to conduct a criminal investigation in any case. The facility is not a US-style voluntary disclosure and does not deliver the same protection.

Where deliberate conduct is in issue, the UK analogue of the Voluntary Disclosure Practice is Code of Practice 9 and the Contractual Disclosure Facility, described at gov.uk/guidance/admitting-tax-fraud-the-contractual-disclosure-facility-cdf. Under it, HMRC offers a contract: a complete and accurate disclosure of the deliberate conduct in exchange for HMRC not pursuing a criminal investigation into that conduct. The taxpayer has 60 days from receiving the offer to return the acceptance letter with a valid outline disclosure, and HMRC's published position is that if it has not heard within that period it treats the silence as rejection and may begin a criminal investigation into the suspected fraud.

Two cross-border traps follow. First, the sequencing. A disclosure made to one revenue authority becomes a document that can be sought by the other, and the two narratives must be consistent, which means they should be drafted together rather than in whichever order the deadlines happen to fall. Second, the tests do not match. HMRC's concept of deliberate behaviour and the IRS concept of willfulness overlap but are not the same, and a UK adviser's comfortable conclusion that a UK disclosure can be made on a careless rather than deliberate basis is not a conclusion about the US position and should never be treated as one.

How we sequence the decision in practice

The failure mode we see most often is a package built first and a willfulness question asked at the end, when the returns are already prepared and the client wants to sign. By then the incentive to reach the convenient answer is at its highest and the cost of changing route is at its greatest. The order below is deliberately the reverse.

Confirm nothing has already started. Check for any open IRS examination for any year, any IRS Criminal Investigation contact, and any correspondence indicating third-party information has reached the IRS. If any of these exists, both routes are closed or compromised and the position changes entirely.
Collect the evidence before forming a view. Signed returns and the answers given at Schedule B line 7a, engagement letters, adviser correspondence, bank and platform self-certifications, employer share plan communications, and anything showing when the obligation was first mentioned to you.
Take the willfulness question under privilege. It is a legal question about state of mind evidenced by documents, and it should be answered by counsel on the whole file, not by a preparer on a summary.
If the answer is non-willful, test the non-residency position. Abode and the 330-day count decide whether the foreign branch and its zero penalty component apply, or the domestic branch and its 5 percent charge.
If the answer is willful or genuinely unclear on bad facts, do not sign a certification. Preclearance under Form 14457 is the route that addresses criminal exposure, and it is entered with US counsel from the outset.
Run the UK analysis in parallel. Establish whether a Worldwide Disclosure Facility disclosure or a Code of Practice 9 position is required, and align the two narratives before either is filed.
Build the numbers only once the route is fixed. Sterling to dollar conversions, FBAR maximum values, income schedules and any penalty base are route-specific work, and rebuilding them after a change of direction is expensive.

There is one more discipline worth stating plainly. IRS Streamlined Filing is generous precisely because it is narrow, and it is not made less narrow by the strength of a client's wish to use it. Where the facts support the certification, it is the right route and it should be used without hesitation or apology. Where they do not, the correct answer is the harder one, and giving it early is the whole value of getting cross-border advice at all.