Missed US Tax Returns: Americans at International Bodies

Americans employed by an international organisation in London often have Missed US Tax Returns because their salary is exempt from UK income tax and paid gross. That UK exemption does not bind the IRS. A US citizen's salary is fully reportable, and unfiled years can usually be regularised without penalty.

This guide is written for senior professionals: directors, economists, lawyers, engineers and policy specialists who hold a US passport or a green card and work for an intergovernmental or international body headquartered or represented in London. At Jungle Tax we prepare catch-up filings for this group regularly, and the pattern is remarkably consistent. The payslip shows no tax deducted, the organisation's privileges order confirms the salary is exempt, HMRC never sends a return, and years pass before anyone realises the US position is entirely different. What follows explains why, what is actually owed (often far less than people fear), and how to bring every year up to date in the right order.

Why does a UK-exempt salary still create a US filing obligation?

The United Kingdom grants income tax exemption to qualifying officials of international organisations through Orders in Council made under the International Organisations Act 1968. Each order sets out which staff are covered and on what terms. HMRC's own guidance on how individuals claim the exemption, including the certificate of official status the organisation issues, is set out in its International Manual at INTM860720.

That exemption is a concession by the host state. It says nothing about how the United States taxes its own citizens. The US taxes citizens on worldwide income wherever they live, and nothing in the UK order, in the organisation's founding agreement or in the US-UK income tax treaty removes that. The IRS states plainly on its page for employees of foreign governments or international organizations that US citizens and resident aliens generally do not qualify for the exemptions available to foreign staff.

The practical consequence is that the salary goes on Form 1040 as wages, in full, for every year of employment. The fact that it arrives with no deductions is not a signal that nothing is due. It simply means that no one, anywhere, is withholding on the American's behalf.

Why the section 893 exemption does not help US citizens

US domestic law contains its own exemption for international organisation staff. Internal Revenue Code section 893 excludes from gross income the compensation an employee of an international organisation receives for official services, but only where the employee is not a US citizen. A US citizen can never rely on it, whatever their role, grade or length of service. Dual nationals are treated as US citizens for this purpose, so a British-American official is in exactly the same position as an American with no other passport.

The narrower position for green card holders

Lawful permanent residents are in a different, more technical position. Because section 893 applies to non-citizens, a green card holder is not automatically excluded from it. However, section 893(b) removes the exemption for anyone who has filed the waiver required by section 247(b) of the Immigration and Nationality Act, made on USCIS Form I-508, under which the individual waives the rights, privileges and immunities that would otherwise attach to their international organisation employment in order to obtain or keep permanent resident status. The IRS confirms that signing that waiver means the tax exemption is no longer available.

Whether a particular green card holder signed Form I-508, and whether the exemption can properly be claimed on the facts, needs to be established from their immigration file rather than assumed. Even where a green card holder can exclude the salary, they remain a US tax resident with worldwide filing obligations on everything else, including FBAR and Form 8938 reporting. Anyone tempted to treat themselves as non-resident under the treaty instead should take advice first, because that position has consequences of its own for long-term residents.

How the salary is taxed in the US

For a US citizen based in London, the salary is foreign earned income. It is reported as wages, and in almost every case the key relief is the foreign earned income exclusion, claimed on Form 2555.

Does an international organisation salary qualify for the foreign earned income exclusion?

Generally, yes. The exclusion is denied for pay received as an employee of the United States government or its agencies. An intergovernmental organisation is a separate international body, not a US government employer, even where the United States is a member state or a major contributor. Salary for work performed in the UK is therefore foreign earned income in the ordinary way, provided the individual meets either the bona fide residence test or the physical presence test. A senior official living in London on a multi-year contract will usually satisfy the bona fide residence test comfortably.

The exclusion was set at $130,000 for 2025 and is indexed annually, rising to $132,900 for 2026. A married couple who both work abroad can each claim their own exclusion against their own earnings. A separate foreign housing exclusion can shelter part of London housing costs above a base amount, subject to a cap that is higher for London than the standard limit because the IRS recognises it as a high-cost location. Where the organisation provides a housing or expatriation allowance, that allowance is itself earned income and is counted before the exclusions are applied.

What happens when there is no UK tax to credit?

This is where international organisation staff differ from almost every other American in London. A typical US expat employed by a UK company pays UK income tax at rates that equal or exceed US rates, and the foreign tax credit wipes out most or all of the US liability. An official on an exempt salary has paid no UK tax on that salary at all, so there is nothing to credit.

The foreign earned income exclusion therefore does all the work, and only up to its limit. Senior salaries at these organisations, particularly once allowances are included, frequently exceed the exclusion and housing amounts combined. The excess is fully taxable in the US, and under the stacking rule it is taxed at the marginal rates that would apply if the excluded income had not been excluded. In other words, the first dollar above the exclusion is taxed at a high bracket, not at 10%. For a senior economist or director, the net US liability after the exclusion can be a substantial five-figure sum each year.

It follows that some officials owe nothing after the exclusion, while others owe significant tax, and it is impossible to know which category applies without preparing the returns.

Is there US self-employment tax on the salary?

This is widely misunderstood, including in some professional commentary. Service for an international organisation is excepted from employment for FICA purposes, so the organisation does not withhold US Social Security or Medicare. To fill that gap, section 1402(c)(2)(C) treats a US citizen employed by an international organisation as carrying on a trade or business for self-employment tax purposes.

Crucially, that rule applies only to services performed in the United States and its territories. The IRS's self-employment tax guidance for international taxpayers confirms that where the services are performed elsewhere, the earnings are exempt from self-employment tax. For a US citizen working in London, salary for work done in London does not attract US self-employment tax, and the foreign earned income exclusion (which does not reduce self-employment tax in any case) is not needed for that purpose.

Two refinements matter. First, days worked in the United States, for example on mission travel or at a Washington or New York office, produce US-source earnings that are subject to self-employment tax and cannot be excluded under Form 2555. Anyone who spends meaningful time in the US on official business needs a day-by-day workday allocation. Second, the US-UK totalization agreement exists to prevent double social security contributions, but it only becomes relevant where both systems would otherwise apply. Many international organisations sit outside UK National Insurance and run their own staff social security or savings arrangements, so whether a certificate of coverage is available or needed depends on the organisation's arrangements and the individual's history, and should be checked rather than assumed.

Quarterly estimated tax: the ongoing obligation nobody mentions

Because nothing is withheld, any US liability above the exclusion must be paid through quarterly estimated tax on Form 1040-ES. Payments fall due in April, June, September and January. A taxpayer generally owes an underpayment penalty if they expect to owe $1,000 or more when they file and have not paid enough through estimates.

Once the back years are cleaned up, the forward plan should include a safe-harbour estimate. For higher earners with adjusted gross income above $150,000, the safe harbour is 110% of the prior year's total tax, or 90% of the current year's tax. Setting this up as a standing instruction from a UK bank account avoids the underpayment penalty that otherwise recurs every year even after the individual is fully compliant.

Internal tax reimbursement arrangements for US staff

Some international organisations recognise that their American staff are the only nationals who pay home-country income tax on an otherwise exempt salary. To preserve equality of pay between nationalities, they operate an internal reimbursement arrangement under which the organisation refunds the US federal (and sometimes state) income tax attributable to the organisational salary. Others make no such provision, and the cost falls on the employee.

Where a reimbursement scheme exists, several points follow:

• The reimbursement is itself taxable income in the year received, which usually lags the year to which the tax relates. That creates a rolling cycle that must be modelled correctly across years, particularly in a catch-up filing.
• Schemes typically require evidence: filed returns, computations and sometimes a prescribed calculation method. Staff who never filed may have forgone reimbursements they were entitled to, and should check whether late claims are accepted.
• Schemes often assume the exclusion is or is not claimed. Some require the employee to maximise available reliefs; others calculate the refund on a basis that ignores them. The filing position should be chosen with the reimbursement rules in view, not independently of them.
• Advances and repayment obligations can arise where the organisation pays an estimate up front, and they should be reconciled on the return.

We do not name or comment on individual organisations' schemes, and the terms differ markedly. The organisation's staff rules or human resources team are the source for the precise mechanics.

The UK side: what the exemption does and does not cover

The UK exemption covers the official salary and emoluments within the scope of the relevant order. It does not make the individual exempt from UK tax generally. An American official who is UK resident under the statutory residence test remains within UK tax on:

• UK rental income, bank interest, dividends and investment income;
• capital gains on UK and, depending on the regime that applies, overseas assets, including the sale of a London property that is not fully covered by private residence relief;
• a spouse's own earnings and investment income, which are taxed separately;
• any consultancy, board or teaching income earned outside the official role.

HMRC's guidance notes that, although some international agreements allow an exempt salary to be taken into account when setting the rate of tax on other income, the UK does not do so. Other income is taxed at the rates that would apply without the exempt salary. That frequently means low UK tax on modest investment income, which in turn means little UK tax to credit against the US tax on that same income.

From April 2025 the UK moved from the remittance basis to a residence-based regime, with a four-year foreign income and gains relief for new arrivals. Officials who arrived recently or plan to leave should consider how that regime interacts with their US position. Our UK tax services team handles the Self Assessment side where it is required.

US and UK treatment compared

Item	United States (US citizen)	United Kingdom (UK-resident official)
Official salary	Fully reportable as wages; section 893 unavailable to citizens	Exempt under the organisation's Order in Council
Main relief	Foreign earned income and housing exclusions (Form 2555)	Not applicable; salary outside UK tax
Tax credit for the other country	No UK tax on salary, so no credit available against it	Not relevant to the salary
Social security on salary	No self-employment tax on work done outside the US; US workdays are subject to it	Depends on the organisation's arrangements; many sit outside UK National Insurance
Withholding	None; quarterly estimates required on any balance	None on the exempt salary
Other income	Worldwide income taxable; foreign tax credit for UK tax paid on it	Taxable at normal rates; exempt salary not taken into account
Account reporting	FBAR and Form 8938 on UK accounts and certain staff funds	No equivalent disclosure regime for residents

Catching up on missed US tax returns

Most officials in this position did not set out to avoid anything. They were told by colleagues or human resources that the salary was exempt, they had no withholding and no correspondence from the IRS, and they reasonably believed nothing was required. That is exactly the non-wilful profile the IRS's catch-up procedures were designed for.

Streamlined Foreign Offshore Procedures

The Streamlined Foreign Offshore Procedures, described on the IRS page for US taxpayers residing outside the United States, are the usual route. The submission comprises:

• the three most recent years of US income tax returns for which the due date (including extensions) has passed, with all international information returns;
• the six most recent years of FBARs;
• Form 14653, a signed certification that the failures resulted from non-wilful conduct, with a narrative explaining the facts;
• payment of any tax and interest due for the three years.

Eligibility requires meeting the non-residency test: for a US citizen or green card holder, having no US abode and being physically outside the United States for at least 330 full days in at least one of the three most recent years covered. A London-based official almost always meets this. Where the procedures apply, there is no failure-to-file, failure-to-pay or accuracy penalty, and no FBAR penalty. Our IRS streamlined filing specialists prepare these submissions end to end.

Late foreign earned income exclusion elections

The exclusion is an election. It is normally made on a timely return, but the regulations allow it to be made on a late return where the IRS has not discovered the failure to elect, with a statement at the top of Form 2555. Filing before the IRS makes contact therefore preserves the exclusion, which for this group is usually the single most valuable relief. That is a strong reason to act before any correspondence arrives rather than after.

What if there is tax to pay?

Where salary exceeds the exclusion, the three streamlined years will show tax due. Interest runs from the original due dates, and the amount should be calculated precisely and paid with the submission. Where an organisational reimbursement scheme exists, the timing of any refund claim should be coordinated with the filing.

FBAR, Form 8938 and staff savings or provident funds

UK current accounts, savings accounts, investment accounts and ISAs are foreign financial accounts. An FBAR is required where the aggregate maximum value of all foreign accounts exceeded $10,000 at any time in the year. Form 8938 applies separately at higher thresholds; for a US person living abroad, the threshold starts at $200,000 at year end or $300,000 at any time for a single filer, doubled for joint filers. Our FBAR penalty calculator illustrates the exposure the streamlined route removes.

Many international organisations operate a staff savings or provident fund in which part of the salary, often with an employer contribution, is accumulated on the employee's behalf. The US treatment of these funds is genuinely technical. Depending on how the fund is constituted, who controls withdrawals and how assets are held, it may be a reportable foreign financial account for FBAR, a specified foreign financial asset for Form 8938, and it may give rise to current-year income inclusions on contributions or growth. Some funds invest through pooled vehicles with their own US reporting consequences. There is no single answer across organisations, and the analysis should be done from the fund's rules before any return is filed. A conservative disclosure position is usually preferable to omission in a streamlined submission.

A practical sequence for the catch-up

1. Gather the facts: employment dates, the organisation's certificate of official status, payslips or annual salary statements, allowance breakdowns, travel records showing US workdays, UK bank and investment statements, and the rules of any staff savings or provident fund.
2. Confirm status: citizenship, dual nationality, or green card and whether Form I-508 was signed.
3. Model all open years with and without the exclusion and housing exclusion, including any reimbursement income, to decide the filing positions.
4. Prepare the streamlined package: three years of returns, six years of FBARs, Form 14653 with a precise narrative, and payment.
5. Review the UK position: confirm the exemption certificate is in place and that other UK income has been reported under Self Assessment where required.
6. Set up the future: annual filing calendar, quarterly estimated tax, and reimbursement claims where the organisation offers them.

For officials with material investment portfolios, UK property or a spouse with separate income, our high-net-worth practice coordinates the full picture so that the US and UK returns are prepared consistently.

Speak to a US-UK specialist

An exempt salary and a clean UK position can conceal several years of US non-compliance, but for most officials the solution is orderly, penalty-free and often less costly than expected. If you are an American working for an international organisation in London and have not filed, contact our cross-border team for a confidential consultation. We will review your status, model the liability and prepare every return and FBAR needed to bring you fully up to date.