Introduction A US citizen living in the UK who holds undisclosed offshore accounts faces two separate disclosure obligations — one to the IRS and one to HMRC. Both tax authorities now receive account data automatically. Both have penalty regimes that escalate with delay. And neither disclosure route is designed with the other in mind — […]
A US citizen living in the UK who holds undisclosed offshore accounts faces two separate disclosure obligations — one to the IRS and one to HMRC. Both tax authorities now receive account data automatically. Both have penalty regimes that escalate with delay. And neither disclosure route is designed with the other in mind — creating a parallel compliance challenge that requires specialist accountants in the US and the UK who understand both systems simultaneously.
This guide explains the offshore account disclosure landscape for US citizens in the UK in 2026. It covers HMRC’s Worldwide Disclosure Facility, the Code of Practice 9 for serious non-compliance, HMRC nudge letters, the IRS Streamlined program and Voluntary Disclosure Program, and how to manage parallel disclosure to both authorities without creating inconsistency or additional risk. Visit our advisory service:
https://www.jungletax.co.uk/services/us-uk-tax/
Accountants in the US and the UK who specialize in offshore account disclosure are advisers who understand both HMRC’s disclosure facilities — the Worldwide Disclosure Facility and Code of Practice 9 — and the IRS voluntary compliance routes — the Streamlined Compliance Initiative and the Criminal Investigation Voluntary Disclosure Program. These are separate legal frameworks with different procedural requirements, different penalty regimes, and different timelines. An adviser who understands only the HMRC side cannot manage the IRS disclosure. An adviser who understands only the IRS side cannot manage the HMRC disclosure. Both must be managed simultaneously — and consistently.
The IRS guidance on voluntary disclosure is published at:
A US citizen with undisclosed UK accounts has both a UK tax compliance gap — if UK income tax was not paid on offshore income — and a US compliance gap — if US federal returns and FBARs were not filed. The two gaps are related but distinct. The HMRC disclosure resolves the UK gap. The IRS disclosure resolves the US gap. The two disclosures must be consistent — the income figures, account balances, and timelines must not contradict each other. A specialist accountant for the US and UK practices prepares both disclosures simultaneously.
HMRC has been sending nudge letters to individuals identified through FATCA data exchange as US persons with UK accounts. The nudge letters ask recipients to confirm that their UK tax affairs are in order — or to make a disclosure if they are not. Receiving a nudge letter is not an investigation — but it is a signal that HMRC has data about the recipient’s accounts. Voluntary disclosure after a nudge letter is still available — but acting before a formal investigation begins is significantly more favorable than waiting.
HMRC’s Worldwide Disclosure Facility allows individuals to disclose previously undisclosed offshore income and gains voluntarily — before HMRC opens a formal investigation. The WDF provides access to reduced penalties compared to those assessed following a formal investigation. The facility is available online through HMRC’s digital disclosure service.
Our guide to offshore account disclosure for US-UK taxpayers is at:
https://www.jungletax.co.uk/jungle-tax-news-updates/us-and-uk-tax-advisors-offshore-disclosure/
For US citizens whose non-compliance was non-wilful, the IRS Streamlined Foreign Offshore Procedures waive all FBAR penalties and require only three years of federal returns and six years of FBARs. The Streamlined program can be managed in parallel with an HMRC WDF disclosure, with the adviser ensuring that the income figures in both disclosures are consistent.
The WDF is HMRC’s primary voluntary disclosure route for offshore non-compliance. It covers undisclosed foreign income, gains, and assets that should have been included in UK tax returns. The disclosure covers up to twenty years of non-compliance — the exact period depends on the nature of the non-compliance (innocent error, careless, or deliberate).
The WDF penalty regime depends on the territory in which the offshore income or assets are held and on the taxpayer’s behavior. For non-disclosure, the taxpayer’s penalty. lties typically range from 10 to 30 percent of the tax owed. For deliberate non-compliance, penalties can reach 200 percent of the tax owed. The WDF provides access to penalty reduction, down to a minimum of 30 percent for the most serious cases where the taxpayer cooperates fully.
Where HMRC has reason to suspect deliberate non-compliance — tax fraud — it may issue a Code of Practice 9 investigation. COP9 allows the taxpayer to make a full disclosure under the Contractual Disclosure Facility — in exchange for immunity from criminal prosecution. COP9 is a serious investigation framework, not a voluntary disclosure route. Specialist accountants for the US and UK who receive a COP9 letter on behalf of a client engage specialist tax investigation solicitors alongside the tax advisers.
HMRC nudge letters are not formal investigations — they are pre-emptive compliance prompts sent to individuals identified through data exchange (FATCA, CRS, or other international information sharing). The nudge letter asks the recipient to check their tax position and make a disclosure if required. Receiving a nudge letter is not a finding of non-compliance — but ignoring it is inadvisable. The adviser reviews the nudge letter, assesses the taxpayer’s position, and determines whether a WDF disclosure is required or whether the taxpayer’s affairs are already in order.
For US citizens whose non-compliance was non-wilful, the Streamlined program covers three years of federal returns and six years of FBAR filings. All FBAR penalties are waived. The non-wilfulness certification must be accurate and consistent with the UK disclosure narrative. A specialist accountant for US and UK practice prepares the IRS Streamlined submission and the HMRC WDF disclosure simultaneously — ensuring consistency.
The adviser begins by assessing the full extent of non-compliance in both the UK and the US. For the UK side: what offshore income was not declared on UK self-assessment returns, what offshore gains were not reported, and what offshore assets were held that should have been declared. For the US side: which years of federal returns were not filed, which FBARs were not filed, and whether the non-compliance was wilful or non-wilful.
The adviser selects the appropriate disclosure route for each jurisdiction independently. For HMRC: WDF or COP9, depending on the nature of the non-compliance. For the IRS: Streamlined program for non-wilful non-filers, or Criminal Investigation VDP for wilful non-compliance. The routes are independent — a taxpayer can use the WDF for HMRC and the Streamlined program for the IRS simultaneously.
The adviser prepares both disclosures simultaneously — using the same underlying financial data. The income figures, account balances, and tax calculations in the HMRC and IRS disclosures must be consistent. A UK income figure that differs between the two disclosures creates a risk of challenge from either authority.
The adviser typically files the IRS Streamlined submission first — because IRS processing times are longer and the Streamlined program has no deadline. The HMRC WDF disclosure is filed within the timeline required by HMRC — typically within 90 days of the initial notification. The adviser monitors both disclosures through to acceptance and manages any correspondence from either authority.
The HMRC Worldwide Disclosure Facility guidance is at:
https://www.gov.uk/guidance/worldwide-disclosure-facility-make-a-disclosure
Oliver is a US citizen who has lived in London since 2012. He holds a UK current account, a UK investment account, and a legacy Swiss bank account inherited from his grandfather in 2015. The Swiss account generates approximately $18,000 of interest and dividends annually. Oliver has not declared the income from the Swiss account on his UK self-assessment returns and has not filed US federal returns or FBARs for any year since his arrival.
Jungle Tax assessed Oliver’s position. The UK non-compliance was careless — Oliver had not declared the Swiss income on his self-assessment returns, but had not deliberately concealed it. The WDF was the appropriate HMRC route. The US non-compliance was non-wilful — Oliver had not known about the US filing obligation for Americans abroad. The Streamlined Foreign Offshore Procedures was the appropriate IRS route.
Jungle Tax prepared both disclosures simultaneously. The Swiss account income — converted to sterling at the relevant year’s exchange rate — appeared on the HMRC WDF disclosure and on the US federal returns for the catch-up years. The figures were consistent across both disclosures. The Swiss account appeared on the FBAR for all six catch-up years.
The HMRC WDF disclosure covered eleven years of undisclosed Swiss income. The additional UK tax and interest owed was approximately £28,000. The penalty — reduced for full cooperation under the WDF — was approximately £4,200 (15 percent of the tax). The IRS Streamlined submission covered three years of federal returns and six years of FBARs. No additional US tax was owed — the FTC from UK income tax eliminated the US liability on the employment income, and the Swiss income FTC from Swiss withholding tax offset the US liability on the investment income. The FBAR penalty waiver — applied to the Swiss account — eliminated a theoretical post-Bittner exposure of $60,000.
A US citizen who resolves their HMRC offshore disclosure without simultaneously addressing the IRS filing gap creates a consistent HMRC record but a continuing IRS non-compliance. The IRS receives FATCA data from HMRC — including data from the WDF disclosure. A taxpayer who discloses to HMRC but not to the IRS is visible to the IRS as having acknowledged offshore non-compliance. The IRS filing gap must be resolved simultaneously.
The income figures in the HMRC WDF disclosure and the IRS Streamlined submission must be identical — adjusted only for the currency conversion difference between sterling and dollars. An adviser who prepares the two disclosures independently — using different underlying data sources — risks creating inconsistencies that either authority could identify. The specialist accountants for the US and UK use the same underlying financial data for both disclosures.
An HMRC nudge letter is not an investigation — but it is a data signal. The taxpayer named in the nudge letter has been identified through FATCA or CRS data exchange. Ignoring the letter and hoping HMRC does not follow up is not a strategy. The adviser reviews the nudge letter immediately and determines whether a WDF disclosure is required — before HMRC escalates from a nudge to a formal inquiry.
The HMRC WDF resolves the UK tax non-compliance. It does not affect the IRS FBAR penalty exposure. A taxpayer who completes a WDF disclosure but does not file a Streamlined submission continues to accumulate IRS FBAR penalty exposure for the missing years. The two disclosure routes are independent — both must be completed for the taxpayer to be fully compliant in both jurisdictions.
The HMRC WDF guidance for offshore non-compliance is at:
https://www.gov.uk/guidance/worldwide-disclosure-facility-make-a-disclosure
Jungle Tax is a specialist US-UK cross-border tax advisory firm whose accountants for the US and UK team includes IRS Enrolled Agents and UK-qualified tax practitioners with specific experience managing parallel HMRC and IRS offshore account disclosures. We assess the full extent of non-compliance in both the TK and the US at the outset of every engagement. We select the appropriate disclosure route for each jurisdiction independently — WDF or COP9 for HMRC, Streamlined or IRS VDP for the IRS. We prepare both disclosures simultaneously using consistent underlying financial data. We monitor both disclosures through to acceptance and manage all correspondence from both authorities. We ensure that the non-wilfulness certification for the IRS Streamlined submission is consistent with the narrative submitted to HMRC.
Read our guide on how the Streamlined vs Voluntary Disclosure routes compare:
Offshore account disclosure for a US citizen in the UK requires parallel action in two jurisdictions — HMRC and the IRS. Specialist accountants for the US and UK who understand both disclosure frameworks are the only advisers who can manage this correctly.
Three points matter most. First, the HMRC WDF and the IRS Streamlined submission must be prepared simultaneously — using consistent income figures and account data. Second, receiving an HMRC nudge letter is a trigger for immediate action — not a reason to wait. Third, the HMRC WDF does not affect the IRS FBAR penalty exposure — both disclosures are required for full compliance in both jurisdictions.
Jungle Tax | mailto:hello@jungletax.co.uk | 0333-8807974 | https://www.jungletax.co.uk
The WDF is HMRC’s voluntary disclosure route for offshore non-compliance. Any UK taxpayer with undisclosed offshore income or assets can use it before a formal HMRC investigation begins.
Yes. The two routes are independent. A US citizen can make a WDF disclosure to HMRC and a Streamlined submission to the IRS in the same period — with consistent income figures across both.
Contact a specialist immediately. A nudge letter signals HMRC has your account data. Voluntary disclosure is still available — but the window closes if HMRC opens a formal inquiry.
No. The WDF is a UK disclosure only. It does not affect IRS penalties. You must file a separate IRS Streamlined submission to resolve the US FBAR penalty exposure independently.
COP9 is HMRC’s serious fraud investigation framework. It applies where HMRC suspects deliberate tax fraud. It is not a voluntary disclosure route — it requires specialist legal and tax representation from day one.
Up to 20 years for deliberate non-compliance, up to 6 years for careless, and 4 years for innocent error. The adviser assesses the correct period based on the nature of the non-compliance.
