Tax Specialists for US and UK

Tax specialists for US and UK prepare the American and British returns of one person as a single, coordinated piece of work. They decide which country has first claim on each item of income, apply the treaty, claim credits in the right order and file the account reporting both governments expect. You need one if you hold a US passport and live in Britain, if you are British with American income, or if you are about to move between the two.

That definition sounds administrative. In practice it is where most of the money is won or lost. Two competent returns prepared in isolation can each be technically defensible and still leave the same salary, dividend or gain taxed twice, because neither preparer could see the other side. At Jungle Tax we prepare both sides from one file, and this page sets out the specialist knowledge that sits underneath that work: how residence is tested, how the treaty really behaves for US citizens, which credit or exclusion to claim, what the IRS expects to see about British accounts and funds, and the specific moments when a generalist is no longer enough. If you already know you need tax specialists for US and UK, the service page explains how we take on a dual-filing household.

• The US taxes by citizenship. A US passport holder files a Form 1040 wherever they live, and reports foreign accounts separately.
• The UK taxes by residence. The Statutory Residence Test decides whether Britain taxes your worldwide income in a given 6 April to 5 April year.
• The treaty allocates, it does not exempt. For US citizens the saving clause keeps most treaty relief out of reach, so credits do the heavy lifting.
• British investments often trouble the IRS. ISAs, UK funds and some pooled products carry US reporting and punitive default rules.
• Honest lapses are fixable. The IRS offers several relief routes, and choosing the right one matters more than speed.

What do tax specialists for US and UK actually do?

The job is coordination. Every figure on a US-UK dual return has a twin on the other side, and the two must agree in amount, timing, character and source. A UK salary is employment income on the Self Assessment return and foreign earned income on the Form 1040. A dividend from a US company is foreign income for HMRC and domestic income for the IRS. A gain on the sale of a London flat is a UK chargeable gain, a US capital gain in a different currency with a different cost base, and potentially a credit calculation in two directions. The specialist's work is to map each item across, decide which country taxes it first, and then make the second country give relief for the first country's tax.

Why does a generalist struggle with a dual return?

A capable UK accountant knows the Statutory Residence Test, the personal allowance taper and Self Assessment deadlines. A capable US preparer knows Form 1116, Schedule D and the FBAR. The difficulty is not either body of law on its own; it is the interaction. Consider three problems that only appear when both systems are in view at once:

• A UK pension contribution that restores a client's personal allowance saves UK tax, but it may not reduce US taxable income in the same way, so the foreign tax credit position shifts and excess credits build up in one category.
• A newcomer who claims the UK foreign income and gains regime pays no British tax on certain foreign income, which removes the very credit the US return was expecting to use.
• A British fund held in an ISA is tax-free in London and, for the IRS, may be a passive foreign investment company with its own annual form and a harsh default tax regime.

None of these is exotic for a banker, founder or senior executive in London. Each is invisible to someone who only prepares one side.

Return preparation and compliance, not wealth planning

We should be precise about scope. A US-UK specialist in our sense prepares and files returns, reconciles the two sets of figures, prepares FBARs and FATCA statements, and brings late filers back into compliance with the IRS and HMRC. We do not sell investment products or structure family wealth. For the practical side of hiring a firm, including fee drivers, qualifications and the onboarding process, our sister guide on choosing accountants for US and UK returns covers that ground. This page stays with the technical question of how the two systems collide.

Why do Americans in the UK file in both countries?

Because the two countries use different connecting factors. The United States looks at who you are. The United Kingdom looks at where you are. A US citizen resident in London is therefore inside both systems at the same time, and nothing in the treaty changes that basic fact.

The US taxes by passport

The IRS guidance for US citizens and resident aliens living abroad is unambiguous: citizens file on worldwide income wherever they live, subject to the same filing thresholds as anyone else. Americans overseas receive an automatic two-month extension, moving the calendar-year deadline from 15 April to 15 June, although interest on unpaid tax still runs from April. Dual nationals who have never lived in America, sometimes called accidental Americans, are in exactly the same position as a New Yorker on secondment.

The UK taxes by residence

HMRC's starting point is simpler. If you are UK resident in a tax year you are normally taxed on worldwide income and gains. If you are not resident, you are taxed only on UK-source income such as British rental profits or UK employment duties. HMRC's overview of tax on foreign income confirms that the old domicile-based exemption ended on 6 April 2025 and that relief for foreign income is now limited to eligible new arrivals.

Two tax years that never line up

The UK year runs from 6 April to 5 April. The US year is the calendar year. Every UK tax year therefore straddles two US returns, and the matching of tax paid to income taxed has to be done month by month, not return by return. This is the source of many failed credit claims.

UK tax year	UK dates	US returns it touches	What the preparer must do
2025/26	6 April 2025 to 5 April 2026	2025 Form 1040 (roughly nine months) and 2026 Form 1040 (roughly three months)	Allocate UK salary, PAYE and Self Assessment tax to the correct US year
2026/27	6 April 2026 to 5 April 2027	2026 Form 1040 and 2027 Form 1040	Decide whether to claim foreign taxes on a paid or accrued basis and apply it consistently
Year of arrival or departure	Split at the date of the move if split-year treatment applies	One or two US returns, often with part-year FEIE tests	Match UK part-year figures to the US period and recheck FBAR maximum balances

Am I UK tax resident? The Statutory Residence Test explained

UK residence is decided by the Statutory Residence Test in Schedule 45 to the Finance Act 2013. It is a mechanical test applied in a fixed order, and HMRC's detailed guidance, RDR3 on the Statutory Residence Test, runs to many pages because each step contains defined terms. The order matters: you look at the automatic overseas tests first, then the automatic UK tests, and only then the sufficient ties test.

The automatic overseas tests

You are automatically non-resident for a tax year if any of these applies, according to HMRC's page on UK residence and tax:

• You spent fewer than 16 days in the UK.
• You were not UK resident in any of the three previous tax years and spent fewer than 46 days in the UK.
• You worked full-time overseas, averaging at least 35 hours a week, spent fewer than 91 days in the UK, and worked in the UK on no more than 30 of those days.

The automatic UK tests

If no overseas test is met, you are automatically resident if you spent 183 days or more in the UK, if your only home was in the UK for at least 91 consecutive days and you were present there on at least 30 days, or if you worked full-time in the UK for a period of more than 365 days. A senior hire relocating from New York to Canary Wharf usually becomes resident through the day count or the full-time work test in the first year.

The sufficient ties test

Everyone else is judged on ties: family in the UK, available accommodation, substantive UK work, days spent in earlier years and, for leavers, whether you spent more time in the UK than any other single country. The fewer days you spend, the more ties it takes to make you resident. This is where globally mobile clients most often misjudge their position, because a family home kept in Chelsea while the principal commutes from New York can be enough.

Split-year treatment when you arrive or leave

Residence is decided for a whole tax year, but split-year treatment can divide the year of arrival or departure into a UK part and an overseas part. Only certain defined cases qualify, such as starting full-time work overseas or ceasing to have a UK home, and the conditions are strict. Our guide to the statutory residence test and split-year treatment works through the cases that matter for senior movers. For leavers, the final Self Assessment return and HMRC's departure form deserve the same care, because the residence pages are where split-year treatment is claimed.

What if both countries treat you as resident?

A green-card holder or US-resident alien who is also UK resident can be resident in both countries under domestic law. Article 4 of the treaty then supplies a tie-breaker based on permanent home, centre of vital interests, habitual abode and nationality. A US citizen cannot use the tie-breaker to escape US tax because of the saving clause, but a non-citizen can, and the result must be disclosed. The mechanics are set out in our guide to the treaty tie-breaker for dual residents.

Your position	US filing	UK filing	Main relief mechanism
US citizen, UK resident	Form 1040 on worldwide income, FBAR and Form 8938 if thresholds met	Self Assessment on worldwide income (FIG relief if eligible)	US foreign tax credit for UK tax; UK credit for US tax on US-source income under treaty rules
US citizen, not UK resident but with UK income	Form 1040 on worldwide income	Self Assessment on UK-source income only, if required	US foreign tax credit for UK tax on UK-source income
British citizen with US income, UK resident	Non-resident US return only if US-source income requires it	Self Assessment on worldwide income	UK foreign tax credit relief for US tax, limited by treaty rates
Green-card holder, UK resident	Form 1040 unless the status is formally surrendered or a treaty position is taken and disclosed	Self Assessment on worldwide income	Tie-breaker under Article 4, disclosed on Form 8833

How does the UK foreign income and gains regime affect US citizens?

From 6 April 2025 the remittance basis was replaced by a four-year foreign income and gains regime. HMRC's guidance on checking whether you can claim the 4-year FIG regime explains that a qualifying resident is someone within their first four years of UK residence after at least ten consecutive years of non-residence. Eligible foreign income and gains can be exempted from UK tax by claim on the Self Assessment return.

For most people that is a straightforward saving. For a US citizen it can be a trap. The US foreign tax credit only works where foreign tax has actually been paid. If a newly arrived American claims FIG relief on, say, dividends from a European company or interest on an offshore account, no UK tax is paid on that income and there is nothing to credit. The IRS then taxes it in full. Worse, the claim costs the UK personal allowance and the capital gains annual exempt amount for that year, which increases UK tax on the client's London salary. That extra UK tax lands in the general category of the foreign tax credit, where US citizens with UK earnings usually have surplus credit already. The net result can be more tax overall, not less.

Foreign employment income is outside the regime altogether; HMRC points to overseas workday relief for that. Whether a claim makes sense depends on the whole two-country calculation, not the UK line alone. Our UK FIG regime calculator gives a first indication, and the guide to a first FIG claim on the 2025/26 return for Americans shows how we test it on both returns before anything is filed.

How much UK tax will you pay in 2026/27?

No serious comparison of the two systems is possible without the British numbers. The figures below come from HMRC's page on income tax rates and personal allowances for the tax year 6 April 2026 to 5 April 2027, and apply in England, Wales and Northern Ireland. Scotland sets its own bands for non-savings income; see the Scottish income tax rates if you live north of the border.

Income tax bands and the personal allowance

Band	Taxable income	Rate
Personal allowance	Up to £12,570	0%
Basic rate	£12,571 to £50,270	20%
Higher rate	£50,271 to £125,140	40%
Additional rate	Over £125,140	45%

National Insurance for employees

Employees on category A pay Class 1 contributions of 8% on weekly earnings between £242.01 and £967, and 2% above £967, with nothing due below £242, according to HMRC's table of National Insurance rates and category letters. National Insurance is not an income tax for US purposes and is not creditable against US tax; the relationship between the two social security systems is handled by a separate agreement, discussed below.

What is the 60% band between £100,000 and £125,140?

Once adjusted net income passes £100,000, the personal allowance falls by £1 for every £2 of income above that level, and it disappears entirely at £125,140. HMRC explains the rule on its page about income over £100,000, and the statutory basis is section 35 of the Income Tax Act 2007.

The arithmetic is worth seeing. On £100,000 of employment income, UK income tax is £27,432: £7,540 in the basic band plus £19,892 in the higher band. On £125,140 it is £42,516. The extra £25,140 of income therefore costs £15,084 in income tax, an effective 60%. An employee also pays 2% National Insurance on that slice, which takes the marginal cost to 62%.

Adjusted net income is reduced by certain statutory reliefs, principally personal pension contributions and donations under Gift Aid, and HMRC's guidance lists them. The cross-border point is that these reliefs do not translate automatically to the US return. The UK saving reduces UK tax, which reduces the foreign tax available to credit in the US; whether the payment reduces US income is a separate question under US law and the treaty. We calculate both sides whenever a client's income sits in this band, because the answer is rarely what a UK-only calculation suggests.

Worked example: UK tax on $10,000 and $100,000

Readers often ask what a dollar figure means in British tax. The example below uses an illustrative exchange rate of $1.35 to £1, rounded, so $10,000 is treated as about £7,400 and $100,000 as about £74,000. For a real return you would use the rate for the relevant date or the IRS yearly average currency exchange rates on the US side. It assumes employment income only, a UK resident outside Scotland, the full personal allowance and category A National Insurance, with annual thresholds approximated from the weekly figures.

Item (2026/27, illustrative)	$10,000 (about £7,400)	$100,000 (about £74,000)	£100,000 (for comparison)
Personal allowance used	£7,400 of £12,570	£12,570	£12,570
Basic-rate tax at 20%	£0	£7,540	£7,540
Higher-rate tax at 40%	£0	£9,492	£19,892
Total UK income tax	£0	£17,032	£27,432
Employee National Insurance (approx.)	£0	about £3,491	about £4,011
Take-home before other deductions	about £7,400	about £53,477	about £68,557
Typical US position for a US citizen	No US tax; filing depends on the gross-income threshold	UK income tax exceeds the US liability, so the foreign tax credit removes US federal tax and leaves excess credit	As for $100,000, with a larger excess credit

The US column is deliberately qualitative. US federal tax depends on filing status, the standard deduction for the year and any other income, so we compute it on the return rather than quote it here. For a single filer with only UK wages at these levels, the UK income tax is the larger of the two, which is why the foreign tax credit normally leaves nothing to pay in Washington.

Does the US-UK tax treaty stop double taxation?

It prevents most of it, but not in the way people assume. The income tax treaty, published by HMRC among the USA tax treaties and by the IRS with its UK tax treaty documents, allocates taxing rights between the two countries and requires the country of residence to relieve tax paid in the source country. It does not make income disappear. For US citizens the practical relief comes mostly through Article 24 and the foreign tax credit, rather than through exemptions.

The saving clause: why US citizens cannot rely on the treaty

Article 1(4) lets the United States tax its citizens as if the treaty did not exist, subject to a list of exceptions in Article 1(5). The Treasury Technical Explanation of the treaty confirms the intent. So an American in London cannot point to a treaty article that gives the UK exclusive taxing rights over, say, UK bank interest and expect the IRS to stop taxing it. What the American can do is claim a credit for UK tax paid. Our guide on the saving clause for dual nationals walks through the exceptions line by line.

Where the treaty still helps

Treaty feature	Helps a US citizen in the UK?	Why
Article 24 relief from double taxation, including re-sourcing	Yes	Lets UK tax on certain US-source income be credited and prevents a circular credit problem
Saving clause exceptions in Article 1(5)	Yes, for listed articles	Certain provisions, such as those on social security benefits and relief from double taxation, apply despite citizenship
Reduced withholding on dividends and interest	Mostly no	The US still taxes its citizen in full; the rates matter more to British non-citizens with US investments
Article 4 residence tie-breaker	No for citizens, yes for green-card holders	The saving clause overrides it for citizens
Capital gains article	Rarely	The US taxes its citizens on gains regardless; relief is by credit where UK tax is paid

Form 8833 treaty disclosure

Where a return takes a position that relies on the treaty to override US law, it usually has to be disclosed on Form 8833. The IRS page on claiming tax treaty benefits explains the requirement. Failing to disclose carries its own penalty even if the position is correct, which is why we treat the form as part of the return, not an afterthought.

Totalization: the separate social security agreement

National Insurance and US Social Security tax are coordinated by a separate social security agreement, not by the income tax treaty. The IRS summary of totalization agreements explains the principle: you generally pay into one system, not both, based on where you work, with certificates of coverage for temporary postings. The same agreement is the reason UK National Insurance is not a creditable foreign tax on the US return.

Foreign tax credit or foreign earned income exclusion: which works in the UK?

A US citizen in Britain has two main tools against double taxation of earnings. The exclusion removes a slice of foreign earnings from US tax altogether. The credit taxes everything in the US and then subtracts foreign income tax already paid. In a country with rates as high as Britain's, the credit usually wins, but not always, and the choice has consequences for later years. Our FEIE versus foreign tax credit calculator shows the comparison for a given salary before the return is prepared.

The foreign earned income exclusion

According to the IRS page on figuring the foreign earned income exclusion, the maximum is $130,000 for 2025 and $132,900 for 2026, per qualifying person. To qualify you need a tax home abroad and either bona fide residence for an entire tax year or, as the IRS overview of the exclusion puts it, physical presence abroad for at least 330 full days in a 12-month period. The exclusion covers earned income only, not dividends, interest or gains.

The foreign tax credit

The foreign tax credit allows UK income tax to be set against US tax on the same foreign income, claimed on Form 1116. Because UK higher and additional rates exceed most US federal rates on the same income, a London earner claiming the credit usually owes no US federal tax on UK salary and builds up unused credit. Those excess credits can be carried to other years within statutory limits, which becomes valuable in a year with lower UK tax or higher US-only income.

Baskets, carryovers and the tax the credit cannot touch

Credits are calculated separately for categories of income, principally general income such as salary and passive income such as interest and dividends. Surplus credit in one category cannot shelter tax in another. A client with a large UK salary and a US brokerage account can therefore have unusable general-category credits and still owe US tax on passive income. Our guide on foreign tax credit baskets and carryovers covers the allocation rules. A second gap is the net investment income tax, which in the IRS's view is not reduced by foreign tax credits for most taxpayers, so a UK resident with substantial US investment income can owe it even when every other line is covered by credits.

Question	Foreign earned income exclusion (Form 2555)	Foreign tax credit (Form 1116)
What it covers	Foreign earned income up to the annual limit	Any foreign-source income on which foreign income tax was paid
2026 limit	$132,900 per qualifying person	Limited by the US tax on the foreign income in each category
Investment income	Not covered	Covered, in the passive category
Effect on other income	Remaining income is taxed at the rates that would apply without the exclusion	No stacking effect
Unused relief	Lost	Excess credit can be carried to other years within limits
Typical fit for a UK higher-rate taxpayer	Occasionally useful at modest salaries	Usually the better choice

Once the exclusion has been claimed and then revoked, it cannot be claimed again for a period without IRS consent. We model both routes over several years before recommending a first election on a return.

What US reporting applies to UK accounts, ISAs and funds?

Income tax is only half the US compliance picture. The IRS and the Treasury also want to see what you own abroad, and the penalties for missing a form can exceed the tax at stake. Our US tax return services treat these disclosures as part of the core return.

FBAR: the $10,000 aggregate test

A US person must file FinCEN Form 114 if the combined maximum value of their foreign financial accounts exceeded $10,000 at any time in the calendar year, as FinCEN explains on its page about reporting foreign bank and financial accounts. The test is aggregate, so three modest UK accounts can trigger it together, and it includes accounts over which you have signature authority. The FBAR is filed with FinCEN, not with the tax return. If you have missed years, our FBAR penalty calculator gives an indication of exposure before you decide on a route.

FATCA and Form 8938

Form 8938 is a separate IRS disclosure of specified foreign financial assets, filed with the Form 1040 when higher thresholds are met. The two regimes overlap but are not identical; the IRS publishes a comparison of Form 8938 and FBAR requirements that we recommend to anyone who assumes one covers the other.

Why are ISAs not tax-free for the IRS?

An individual savings account is a UK statutory wrapper. The US has no equivalent recognition, so interest, dividends and gains inside an ISA are taxable on the Form 1040 in the year they arise, and there is no UK tax to credit against them. A cash ISA is simply a taxable account for US purposes. A stocks and shares ISA holding UK funds adds a further problem.

PFICs explained, not just named

A passive foreign investment company is, broadly, a non-US company whose income or assets are mainly passive. Most UK-domiciled pooled funds, including unit-linked funds, OEICs and exchange-traded funds, and many UK-listed closed-ended investment companies, fall within the definition. The IRS default regime taxes excess distributions and gains at the highest ordinary rate, spread back over the holding period, with an interest charge. Two elections soften this. A qualified electing fund election taxes your share of the fund's income each year, but requires an annual information statement that most UK funds do not produce. A mark-to-market election taxes the annual increase in value as ordinary income.

British "reporting fund" status, which matters for UK capital gains treatment, has no bearing on the US analysis. Each PFIC holding generally requires Form 8621 every year. The practical answer for most clients is to identify the holdings early and choose the least damaging treatment for each; our guide to the PFIC trap in UK funds and ISAs sets out the options with examples.

What happens if you leave the UK and come back within five years?

The UK temporary non-residence rule catches people who leave, realise gains or certain income while abroad, and return too soon. HMRC's manual at RFIG21510 sets out the conditions: the rule applies if you had sole UK residence in at least four of the seven tax years before departure and your period of non-residence lasts five years or less. To be outside it, the absence has to exceed five years, so five years and a day.

If the rule applies, gains on assets you held when you left, and certain other income, are taxed in the UK in the year you return. The capital gains mechanics are in HMRC's HS278 helpsheet on temporary non-residents.

The US dimension is what makes this a specialist matter. Suppose a US citizen founder leaves London for New York in year one, sells shares in year two while non-resident, and returns to London in year four. The US taxes the gain in year two, and the US return is filed on that basis with no UK tax to credit. The UK then taxes the same gain in year four. Relief for the second tax has to be engineered across returns filed years apart, in different currencies and different tax years. Our guide to the five-year clock for returners explains how we document the position at departure so the credit is available later.

What changed in US tax for 2025 and 2026 that affects UK residents?

The 2025 US tax law, which the IRS now refers to under the heading of new deductions for working Americans and seniors, introduced several changes. Two matter most for Americans in Britain.

The $6,000 senior deduction

For 2025 to 2028, an individual who reaches age 65 by the last day of the tax year can claim an additional deduction of $6,000, or $12,000 for a married couple where both qualify. It is available whether or not you itemise, requires a valid Social Security number, requires married couples to file jointly, and is claimed on Schedule 1-A. It is in addition to the existing additional standard deduction for older taxpayers. The deduction phases out for modified adjusted gross income above $75,000, or $150,000 for joint filers. The IRS sets out the conditions on its page to check eligibility for the enhanced senior deduction.

Nothing in the rules excludes a UK resident. The practical value, however, is often nil for the clients we act for. Many are above the phase-out range, and for those who are not, the foreign tax credit may already reduce US tax on their UK income to nothing. A deduction that lowers US taxable income can still matter where there is US-source income with no UK credit behind it, so we test it rather than assume.

Form 1099 thresholds for freelancers with US clients

British-resident Americans who invoice US clients should know that the Form 1099-NEC reporting threshold rises from $600 to $2,000 for payments made in 2026, according to the IRS page on Form 1099 filing requirements. Separately, the Form 1099-K threshold reverted to gross payments above $20,000 and more than 200 transactions. Fewer information returns does not mean less taxable income: the income is still reportable in both countries.

Behind on US filings? A decision tree for IRS relief

Many of the Americans we meet in London have filed UK returns faithfully for years and never filed a US one, often because nobody told them they had to. The IRS has several routes back, and they are not interchangeable. The wrong choice can cost the protection a better route would have given. Our IRS Streamlined filing specialists handle this work, and the guide on missed US tax returns for Americans in the UK describes the early steps.

Streamlined Foreign Offshore Procedures

For non-residents whose failure was non-wilful, the Streamlined filing compliance procedures are usually the right route. Under the version for US taxpayers residing outside the United States, you file the most recent three years of returns and the most recent six years of FBARs, pay any tax and interest due, and sign Form 14653 certifying that the failure was not wilful. The non-residency test includes being physically outside the US for at least 330 full days in one of the three years. Eligible taxpayers pay no failure-to-file, failure-to-pay or FBAR penalties. For a UK resident, the tax due is often small or nil because UK tax already paid generates credits. Our Streamlined filing calculator and US back tax calculator for expats give a first estimate.

Administrative relief: first-time abatement and its successor

Where a single year was filed or paid late after a clean record, administrative relief may remove the penalty. The IRS page on first-time abate and administrative waivers explains that first-time abatement is transitioning to an Automatic Exemption from Penalty from summer 2026, starting with 2025 tax year returns. It applies where the prior three years were compliant, and it covers failure-to-file and failure-to-pay penalties on the income tax return. It does not reach the separate international information return penalties. Those penalties need a different route.

Reasonable cause

Where administrative relief is unavailable, penalty relief for reasonable cause requires a written explanation showing that you exercised ordinary business care and prudence and still could not comply. Ignorance of the law is rarely enough on its own, but reliance on professional advice, serious illness or events outside your control can be. Reasonable cause is fact-heavy, and the statement has to be written for a human reviewer.

Delinquent submission procedures

Where all income was reported and tax paid, but an information return such as Form 8938 or Form 5471 was missed, the delinquent international information return submission procedures may allow the forms to be filed with a reasonable cause statement. A similar approach has been used for late FBARs where no income was omitted. The comparison of routes is in our guide on delinquent FBAR, Streamlined or voluntary disclosure.

Relief for certain former citizens

People who renounced US citizenship without filing, often dual nationals who left the system years ago, may be able to use the IRS relief procedures for certain former citizens. The procedures carry net worth and tax liability conditions set by the IRS, and many wealthy households will not meet them, so eligibility must be checked before anything is filed.

Your situation	Likely route	What is filed	Penalty outcome
Several years unfiled, living in the UK, not wilful	Streamlined Foreign Offshore	3 years of returns, 6 years of FBARs, Form 14653	Penalties waived if eligible; tax and interest paid
One late return after three clean years	Automatic Exemption from Penalty or first-time abatement	The late return	Failure-to-file and failure-to-pay penalties removed
Income reported, information forms missed	Delinquent submission procedures	Late forms with a reasonable cause statement	Penalties may not be imposed if the statement is accepted
Specific events prevented filing	Reasonable cause request	Returns plus written explanation	Decided on the facts
Renounced without filing	Relief for certain former citizens, if eligible	Returns and expatriation statement as required	Depends on meeting the IRS conditions
Wilful conduct or doubt about it	Specialist legal advice before any filing	Not a return preparation decision	Outside the Streamlined route

When do you need a US-UK tax specialist? A trigger checklist

Many dual-filing households can be served by a careful preparer for years without incident. The picture changes when one of the following events occurs. Each is a point where the two systems interact in a way a single-country preparer is unlikely to catch.

• You are moving from the US to the UK, or the other way, in the current or next tax year.
• You are leaving the UK and may return within five years.
• You are newly resident in the UK and considering a FIG claim.
• Your income crosses £100,000 and enters the tapered band.
• You receive restricted stock units, share options or carried interest with vesting across both countries.
• You hold ISAs, UK funds or UK-listed investment companies as a US citizen.
• You own a UK limited company or a US LLC and live on the other side of the Atlantic.
• You are selling UK or US property or a significant shareholding.
• You have US-source dividends, interest or rental income while resident in the UK.
• You are a green-card holder living in the UK.
• You have years of unfiled US returns or missing FBARs.
• You are turning 65 and want to know whether the US senior deduction is worth claiming.
• You have received an IRS or HMRC letter you do not understand.
• Your two sets of returns are prepared by different firms that do not speak to each other.

If two or more of these apply, the saving from a coordinated return is usually larger than the cost of preparing it properly. The same logic applies to our high-net-worth client work and our wider private client tax services, where several of these triggers tend to arrive at once.

How we prepare a coordinated US-UK return

Our method is consistent, whatever the size of the file. We start with residence: the SRT position for each UK year and the US filing status for each calendar year. We then build a single income map that records every item once, with its UK and US treatment side by side. The UK return is usually prepared first because UK tax on UK income is the credit the US return depends on; where US-source income is involved, the order reverses for that item. Credits are claimed by category and by period, the treaty positions are disclosed, and the FBAR and Form 8938 are reconciled to the same balances. Our UK tax return services and US team work from that shared file, which is why the two returns agree. The broader principle is set out in our guide to avoiding US-UK double taxation for Americans in London.

For questions about engagement terms and what a first year typically involves, the companion page on US and UK accountants and their fees is the right place to start. When you are ready to discuss your own returns, contact our US-UK team with a short outline of your residence history and income sources, and we will tell you plainly what needs to be filed.