US Personal Tax Services: When US Days Make You a US Filer

If you live in the UK, have never held a green card and never filed a US return, your travel diary may still have made you a US tax resident. US Personal Tax Services address this: the substantial presence test counts weighted US days across three years, and crossing it creates a worldwide filing obligation. Jungle Tax resolves the position and the catch-up.

Why does a UK resident with no green card end up filing in the US?

US tax residency is not a matter of immigration status, sentiment or where you consider home. For a non-citizen it is decided by two mechanical tests, and only one of them involves a card. The first is the lawful permanent resident test. The second, and the one that quietly catches London-based investors, investment bankers, private equity principals and founders with a US operating business, is the substantial presence test in section 7701(b)(3) of the Internal Revenue Code.

The substantial presence test does not ask about your visa. A B-1 business visitor, an ESTA traveller under the Visa Waiver Program, an L-1 commuting to a US subsidiary, an E-2 investor and a person carrying nothing but a British passport are all measured on precisely the same ruler: physical presence, counted in days, weighted across a rolling three-year window. If the arithmetic crosses the line, the US treats you as a resident alien for income tax purposes and expects a Form 1040 reporting your worldwide income — your UK salary, your carried interest, your UK company dividends, your investment portfolio, your rental income and your gains, wherever they arise.

The people most exposed are rarely the ones who feel exposed. They are the ones who never moved to the United States at all. They are simply in New York eleven days a month for a live deal, in San Francisco for a fortnight each quarter with a portfolio company, or spending long stretches at a Manhattan apartment they treat as a convenience rather than a residence. No single trip looks meaningful. The aggregate does.

How does the three-year day count actually work?

Per the IRS, you meet the substantial presence test for a calendar year if you satisfy both of the following. First, you were physically present in the United States on at least 31 days during the current year. Second, you were present for 183 days or more over the three-year period comprising the current year and the two immediately preceding years, counting:

• All of the days you were present in the current year;
• One third of the days you were present in the first preceding year;
• One sixth of the days you were present in the second preceding year.

Two features of that formula do the damage. The first is that the 31-day condition is trivially easy for anyone with a US business interest — a single month of travel clears it. The second is that the weighted 183 is not 183 actual days. Because the prior years are discounted rather than ignored, a genuinely repeatable pattern of travel crosses the threshold long before any single year looks like relocation. A steady rhythm of roughly 122 days a year — around ten days a month — produces 122 + 40.67 + 20.33, which equals 183 exactly. Ten days a month, indefinitely, is the tipping point. Most people who cross it were not trying to move anywhere.

The count is of days, not hours. Any part of a day on US soil is a day, including the day you land and the day you depart, so a Monday-morning arrival and a Thursday-evening departure is four days, not three. There is no annual reset and no forgiveness for a light year in isolation: a heavy year continues to contribute at one third and then one sixth for two further years. Someone who has just finished a punishing transaction year can meet the test in the following year on far fewer days than they expect. You can verify the formula and its terms directly on the IRS substantial presence test page.

A worked example: the London deal principal

Consider a UK-resident, UK-domiciled partner at a London investment firm with a US portfolio company. She has never held a green card and has never filed anything in the United States.

Year	Actual US days	Weighting	Days counted
Current year	96	x 1	96.00
First preceding year	180	x 1/3	60.00
Second preceding year	168	x 1/6	28.00
Three-year total	—	—	184.00

In the current year she spent barely a quarter of it in the United States. She was present in the UK for the clear majority of the year, paid UK tax on everything, and would describe herself without hesitation as a British taxpayer. She has nonetheless met the substantial presence test, is a US resident alien for that year, and owes a Form 1040 reporting worldwide income unless she can establish and correctly file one of the two exits described below. Note also the residency starting date: where residency arises through the substantial presence test, it generally begins on the first day of US presence in that calendar year, not the day the counter tipped over 183.

Which US days do not count?

Not every day on American soil is a counted day. The statutory exclusions are narrow, specific and — importantly for our clients — mostly irrelevant to commercial travellers. The IRS excludes:

• Days you commute to work in the US from a residence in Canada or Mexico, if you regularly commute;
• Days you are in the US for less than 24 hours while in transit between two points outside the United States;
• Days you are in the US as a crew member of a foreign vessel;
• Days you are unable to leave the US because of a medical condition that arose while you were in the United States;
• Days you are an exempt individual.

Read that transit exclusion carefully, because it is the one most often misapplied by frequent flyers. It requires that you are travelling between two places outside the United States and that you are in the country for under 24 hours. A Heathrow to JFK flight where you clear immigration and attend a meeting is not transit — it is arrival. A connection through Miami between London and São Paulo, made within the day and without leaving the transit area for other purposes, may qualify. Anyone relying on this exclusion should be able to evidence it with boarding passes, not assertion.

The medical condition exclusion and Form 8843

The medical exclusion applies to a condition that develops while you are in the United States and prevents you from leaving. It does not cover travelling to the US for elective treatment, and it does not cover a pre-existing condition you knew about before you boarded. Where it applies, it must be claimed on Form 8843 with a physician's statement; it is not self-executing.

Who is an "exempt individual"?

The exempt-individual categories are status-based rather than merit-based: foreign government-related individuals on A or G visas (other than A-3 and G-5), teachers and trainees on J or Q visas, students on F, J, M or Q visas, and professional athletes temporarily present to compete in a charitable sports event — each subject to substantial compliance with the visa's requirements and, for teachers and students, to look-back limits on how many years the exemption can be used. There is no category for the business visitor, the director attending board meetings, or the founder overseeing a US subsidiary. If you are travelling on business, your days count.

What actually happens the moment you meet the test?

This is where the exposure stops being theoretical. A resident alien is taxed in essentially the same way as a US citizen. The obligations that switch on include:

• Form 1040 on worldwide income, including UK employment income, self-employment profits, partnership allocations, dividends, interest, capital gains and rental income;
• FinCEN Form 114 (the FBAR), where the aggregate value of your foreign financial accounts exceeded the reporting threshold at any point in the year — for most of our clients, the current account, the savings accounts, the ISAs, the brokerage accounts and any account over which they hold signature authority;
• Form 8938 under FATCA, reporting specified foreign financial assets above the applicable thresholds;
• Form 5471 where you hold a qualifying interest in a UK or other non-US company — the position of almost every founder and many investors;
• Forms 3520 and 3520-A where a foreign trust is involved, which in a UK context can reach certain settlements and, in some analyses, particular pension and savings arrangements;
• PFIC reporting on Form 8621 for UK-domiciled funds, investment trusts and most non-US collective vehicles — including holdings inside a Stocks and Shares ISA, which the US does not recognise as tax-exempt.

That last point deserves emphasis because it is where UK-resident portfolios take the most damage. An ISA is a UK tax wrapper with no US counterpart. The underlying funds are typically passive foreign investment companies, taxed under a punitive default regime with an interest charge on deferred distributions, and each holding is separately reportable. A perfectly sensible, tax-efficient British portfolio can generate a mound of reporting and a materially worse effective rate the moment its owner becomes a US filer. Our cross-border tax team reviews these holdings as a standard part of any presence-test engagement, and the FBAR penalty calculator gives a first indication of the reporting exposure attached to unreported accounts.

Route one out: the closer connection exception and Form 8840

The first exit is a domestic US statutory exception. If you meet the substantial presence test but can show a closer connection to a foreign country, you may be treated as a nonresident. The IRS conditions are cumulative — all must be satisfied:

• You were present in the United States on fewer than 183 actual days during the current year;
• You maintained a tax home in a foreign country during the entire year;
• You had a closer connection to that foreign country (or, in limited cases, to two foreign countries) than to the United States;
• You had not applied for, and did not have pending, an application for lawful permanent residence.

The claim is made on Form 8840, Closer Connection Exception Statement for Aliens, described on the IRS Form 8840 page. If you are filing a US return, it is attached to it; if you are not otherwise required to file, it is sent to the IRS service centre by the return due date. The critical operational point, and the one most often missed: the exception is not a state of affairs you occupy, it is a claim you file. The IRS position is that if you do not timely file Form 8840 you cannot claim the exception, unless you can show by clear and convincing evidence that you took reasonable steps to become aware of the requirement and significant steps to comply. Believing you had a closer connection, and being correct about it, is not a substitute for having filed.

Form 8840 itself asks pointed questions: where your permanent home is, where your family lives, where your personal belongings are, where you are registered to vote, which country's driving licence you hold, where your business activities are conducted, which jurisdiction's forms you sign as a resident, and where your bank accounts and social, political, cultural and religious affiliations sit. For a UK-based principal these answers are usually strong. But note the hard ceiling: fewer than 183 actual days in the current year. Cross that and this route closes entirely, whatever your connections.

Route two out: the US-UK treaty tie-breaker and Form 8833

Where the closer connection route is unavailable — most commonly because actual days reached 183 or more, or because a green card application is pending — the second exit is Article 4 of the US-UK income tax treaty. Where an individual is a resident of both states under each state's domestic law, Article 4 assigns residence to one state through a cascade applied in strict order: permanent home available; then centre of vital interests, meaning where personal and economic relations are closer; then habitual abode; then citizenship; and finally resolution by the competent authorities.

A UK-resident British citizen with a London family home, UK schooling, a UK employer or firm and a UK-centred financial life will normally win that cascade comfortably. But again, the position must be filed. A treaty-based return position is disclosed on Form 8833, Treaty-Based Return Position Disclosure, attached to a Form 1040-NR filed as a dual-resident taxpayer. Silence is not a position. See the IRS Form 8833 page for the disclosure requirement and the penalty for omitting it.

The point almost every generalist page misses

The two exits are not equivalent, and the difference is the single most important thing a UK-resident client should understand. A successful closer connection claim means you are not a resident under section 7701(b) at all. A successful treaty tie-breaker means you remain a resident under US domestic law and are merely treated as a resident of the UK for purposes of the treaty's substantive articles.

The consequence is that the treaty tie-breaker relieves income tax residency; it does not, by itself, switch off the US information-reporting architecture. The FBAR obligation is grounded in a domestic definition of "United States person" that looks to section 7701(b), and the prevailing position is that a treaty tie-breaker does not remove it. Form 8938 has its own rule permitting a dual-resident taxpayer who properly claims treaty nonresident status to be treated as a nonresident for that form. Forms 5471, 3520 and 8621 require their own analysis. Filing an 8833 and assuming the rest disappears is one of the most expensive misconceptions we correct.

Feature	Closer connection (Form 8840)	Treaty tie-breaker (Form 8833)
Source of relief	US domestic statute	US-UK income tax treaty, Article 4
Day ceiling	Must be under 183 actual US days in the year	No day ceiling
Green card applicant	Ineligible if applied or pending	Available; green card holders may use it (with expatriation consequences to consider)
Resulting US status	Nonresident alien for the year	US resident under domestic law, treaty-resident of the UK
Return filed	Form 8840 alone, or with Form 1040-NR if US-source income exists	Form 1040-NR with Form 8833 as a dual-resident taxpayer
Effect on FBAR	Generally removes the obligation	Generally does not remove it
Effect on Form 8938	Generally removes the obligation	May be switched off where the treaty claim is properly disclosed
Risk if unfiled	Exception denied; full resident taxation	Position undisclosed; penalty exposure and resident taxation

How does the UK see the same days?

The UK reaches its answer through an entirely different mechanism, which is why the two systems can both claim you at once. HMRC applies the Statutory Residence Test: automatic overseas tests, automatic UK tests, and then the sufficient ties test, which combines UK days with connecting factors such as family, accommodation, work and prior-year residence. Guidance sits in HMRC's RDR3 note on the Statutory Residence Test.

Question	United States	United Kingdom
Test applied	Substantial presence test, s.7701(b)(3)	Statutory Residence Test
Period measured	Calendar year, weighted over three years	UK tax year, 6 April to 5 April
Prior years	Weighted at 1/3 and 1/6	Relevant through ties and prior residence, not weighted days
Day definition	Any part of a day of presence	Broadly, presence at midnight, with anti-avoidance rules
Non-day-count factors	None in the test itself; relevant only to the exceptions	Central, through the sufficient ties test
Scope once resident	Worldwide income and gains	Worldwide, subject to the UK's current regime for non-domiciled and newly arrived individuals
Exit route	Form 8840, or treaty tie-breaker on Form 8833	Treaty tie-breaker; split-year treatment where applicable

The practical effect is that a mid-Atlantic year can produce genuine dual residence, plus a mismatch of tax years — the US calendar year against the UK's April-to-April year — that makes foreign tax credit relief a matter of careful apportionment rather than arithmetic. Our US tax and UK tax teams work the two sides of the same year together, because relieving double taxation across mismatched years is where unrepresented filers most often overpay.

What does a catch-up look like for someone in this position?

Most people discover this retrospectively: a bank asks for a W-8BEN and the answers no longer fit, a US fund's tax team raises a question, a transaction diligence exercise surfaces the travel record, or an adviser finally adds up the calendar. If several years have already gone unfiled, the sequence matters more than the speed.

Step one: build the day record before you build the position

Reconstruct actual US days for at least the last six calendar years from passport stamps, airline records, expense claims, calendar entries and card statements. Every subsequent decision — whether you crossed the threshold, whether Form 8840 was ever available, which years are open — rests on this schedule. Do not estimate it. In an examination the day count is the first thing the IRS tests, and an unevidenced count is a weak position.

Step two: determine the status year by year

Residency is decided annually. It is entirely normal for a client to be a nonresident in one year, a resident in the next two, and back to nonresident thereafter. Each year is separately analysed and separately remediated.

Step three: choose the disclosure route

For most UK-resident non-citizens with unfiled years and unreported UK accounts, the destination is the Streamlined Foreign Offshore Procedures — but eligibility contains a trap that is specific to exactly this profile. The non-residency requirement for someone who is not a US citizen or lawful permanent resident is that, in one or more of the most recent three years for which the US return due date has passed, the individual did not meet the substantial presence test. A person whose travel pattern has been consistently heavy for years may fail that requirement precisely because they were caught every year. Confirm the position against the IRS streamlined foreign offshore procedures page before proceeding, and see our IRS streamlined filing service for how we run these.

Where streamlined is available, the programme requires returns for the most recent three years for which the due date has passed and FBARs for the most recent six, together with a non-willfulness certification that must be written as a factual narrative, not a form-filling exercise. Where streamlined is not available, alternatives include delinquent international information return procedures, delinquent FBAR submission procedures, or, in willful fact patterns, a voluntary disclosure. What is never advisable is the "quiet disclosure" — filing back years in the post and hoping — which forfeits penalty protection and is specifically identified by the IRS as an unacceptable approach.

Step four: fix the forward position

Remediation without a change of behaviour simply schedules the next problem. Going forward this means an actively managed day budget with a margin of safety rather than a target of exactly 182; timely annual filing of Form 8840 where the closer connection route is genuinely available, filed defensively even in years you expect to be under the threshold; treaty positions properly disclosed where they are not; and a portfolio review to deal with the PFIC and ISA problem before it compounds. Where US days are structurally unavoidable, the planning question becomes how the year is shaped, not whether the forms are filed late.

What do people get wrong most often?

• Counting only the current year. The weighted three-year window is the whole point of the test, and it is what turns a stable travel pattern into residency.
• Assuming 183 means 183. The threshold is a weighted figure. The real-world tipping point for a steady traveller is nearer 122 days a year.
• Treating a position as self-executing. Both exits require a filing. An unfiled closer connection claim is not a claim.
• Miscounting travel days. Arrival and departure days both count. Four calendar dates is four days.
• Believing a treaty claim removes everything. It generally does not remove the FBAR obligation, and it is not a substitute for analysing 5471, 3520 and 8621.
• Ignoring the states. New York and California apply their own residency and allocation rules, and a federal treaty position does not bind a state.
• Filing quietly. Back-filing without a programme forfeits the penalty protection the programmes exist to give.

Speak to us in confidence

If your travel to the United States has become a pattern rather than an exception, the day count deserves a proper answer before someone else asks the question. We will reconstruct the record, determine your status year by year, tell you honestly which exit is available and which is closed, and if the historic position needs correcting, run the catch-up through the right programme with the right narrative. Every conversation is confidential and privileged in the ordinary professional sense, and nothing is filed until you have seen the whole picture. Contact our cross-border team for a discreet, confidential consultation.