US Tax Services for American Expats: London to Zurich Returns

An American who leaves London for Zurich part-way through the year prepares two departure-year returns: a final UK Self Assessment, usually with split-year treatment under the Statutory Residence Test, and a US Form 1040 covering UK and then Swiss income. Swiss filing starts from arrival, and FBAR and Form 8938 must capture accounts in both countries.

At Jungle Tax we prepare these returns for founders, senior executives and investors whose careers have taken them from the City to Zurich. Experienced US tax services for American expats treat the move year as one connected piece of work. The UK, the US and Switzerland each use a different tax year, a different currency and a different idea of when you became, or stopped being, resident, and every figure has to agree across all three. This guide sets out what has to be filed, how each return is put together, where Swiss taxes fit into the US foreign tax credit, and which records to keep. It covers return preparation and compliance only.

Which returns are due for a London-to-Zurich move year?

Take a typical case: a US citizen, resident in London for several years, starts a role in Zurich and moves there in September 2026. The returns for that move are:

• UK Self Assessment for 2026/27 (6 April 2026 to 5 April 2027), with the SA109 residence pages claiming split-year treatment. Filed online by 31 January 2028.
• US Form 1040 for calendar year 2026, reporting worldwide income: UK salary, bonus and investment income up to the move, then Swiss income from arrival. It is due 15 April 2027, with an automatic two-month extension to 15 June 2027 for taxpayers living abroad on the due date, and a further extension to 15 October on Form 4868.
• FinCEN Form 114 (FBAR) for 2026, listing every UK and Swiss account that formed part of an aggregate balance above $10,000 at any point in the year.
• Form 8938, attached to the 1040, where specified foreign financial assets exceed the higher thresholds that apply to filers living abroad.
• The first Swiss return for 2026, covering the period from arrival, with Zurich cantonal and communal tax, Swiss federal direct tax and the year-end wealth statement. Depending on permit and income level this may run through withholding at source (Quellensteuer) with a subsequent ordinary assessment.

Depending on the portfolio, the US return may also need Form 1116 (foreign tax credit), Form 2555 (foreign earned income exclusion, if chosen), Form 8621 for UK or Swiss pooled funds that are PFICs, and Form 8833 if a treaty position is being disclosed.

Why is a London-to-Zurich year harder than a normal expat year?

Most published guidance for Americans in Switzerland assumes you arrive from the United States. Arriving from London changes the work in four ways.

• Three tax years overlap. The UK year runs from 6 April. The US and Swiss years follow the calendar. One UK year spreads its income and tax over two US years, and the first Swiss year starts part-way through the US year.
• Three currencies. UK income is in sterling, Swiss income in francs, and the US return is in dollars. Each foreign tax payment has to be translated using a consistent, documented method.
• Different residence rules at each end. UK residence ends under the Statutory Residence Test. Swiss residence generally starts when you take up residence or register with the commune. The US taxes citizens on worldwide income regardless. Those dates rarely coincide exactly.
• A Swiss tax that the US does not recognise. Switzerland levies an annual wealth tax alongside income tax. Wealthy households pay a meaningful amount of it, but it does not count towards the US foreign tax credit. Most generalist guides skip this point.

Step 1: the final UK Self Assessment and split-year treatment

Are you still UK resident for the year you leave?

Almost always, yes. Someone who has lived and worked in London will normally be UK resident for the whole of 2026/27 under the Statutory Residence Test, because they spend enough days in the UK before leaving or meet one of the automatic UK tests. Without further relief that would mean UK tax on worldwide income for the full year, including Swiss salary earned from September. Split-year treatment exists to prevent that.

Which split-year case applies to a move to Zurich?

For people leaving the UK, HMRC's guidance note RDR3 on the Statutory Residence Test sets out three cases:

• Case 1: starting full-time work overseas. This is the usual case for an executive taking up a Zurich role. It requires sufficient hours of overseas work, limits on UK workdays and UK days for the rest of the tax year, and non-UK residence in the following tax year. The tests are mechanical and unforgiving. A few extra UK workdays during handover can lose the case.
• Case 2: the partner of someone starting full-time work overseas. This covers a spouse or partner who moves to Zurich to live with the person who meets Case 1.
• Case 3: ceasing to have a home in the UK. This covers a person who stops having any UK home and, within six months, becomes tax resident abroad or has a home there. It suits those who are not moving for full-time work. Keeping the London flat available can make this case fail.

Where more than one case could apply, the legislation sets an order of priority, and that order decides the exact split date. We work through each case against the client's travel diary, employment contract and housing position rather than assuming one applies.

What goes on the final UK return?

• Employment income for the UK part, from the P45, P60 or P11D, plus any post-departure payments for UK duties. Bonuses and share awards earned partly in London are apportioned. Getting that apportionment right matters for both the UK and US returns.
• UK investment income for the UK part. After departure, UK-source savings and dividend income is handled under the non-resident rules, which can limit UK tax on certain investment income.
• Capital gains realised during the UK part of the year. Gains after the split date are generally outside UK capital gains tax. The temporary non-residence rules can tax gains on assets held before departure if you become UK resident again within five years.
• The SA109 residence pages, with the split-year claim and the date of departure.

Departing employees often also file form P85 so that HMRC can review PAYE and refund any over-deduction. That does not replace the Self Assessment return where one is required. Our UK tax services team prepares the final return together with the US return so the apportionment is identical in both.

Step 2: the US Form 1040 for a year split between London and Zurich

The IRS does not recognise a split year. A US citizen reports worldwide income for the full calendar year on one Form 1040: UK income from January to the move, Swiss income after it, and investment income from both countries throughout. The US-Switzerland and US-UK treaties both contain a saving clause that generally preserves the US right to tax its citizens. Double tax relief therefore comes almost entirely from US domestic rules, chiefly the foreign tax credit and the foreign earned income exclusion. IRS Publication 54 sets out the framework for citizens living abroad.

Foreign tax credit or FEIE for the move year?

For high earners moving between London and Zurich, the Form 1116 foreign tax credit is usually the better choice. Here is why:

• The exclusion is capped. The FEIE for 2026 is expected to be about $132,900 (verify against the final IRS figure). For a senior executive's package that covers only a small part of earned income. Investment income and capital gains are never excludable.
• UK and Zurich taxes are both substantial. UK income tax on London earnings and Swiss federal, cantonal and communal income tax on Zurich earnings will often exceed the US tax on the same income. That leaves excess credits that can be carried back one year or forward ten.
• Stacking. If the FEIE is claimed, the remaining income is taxed at the rates that would apply if the excluded income had not been excluded. Any foreign tax on excluded income cannot also be credited.
• Revocation has a lock-in. If you claimed the FEIE in earlier London years, revoking it to use credits means you generally cannot elect it again for five tax years without IRS consent. That needs careful thought, but it is rarely a reason to stay with the exclusion for a high earner.

The FEIE can still work for some filers, for example a lower-paid accompanying spouse. Both tests, physical presence and bona fide residence, can be satisfied across two foreign countries, because the question is presence or residence outside the United States, not in one particular country. US workdays during the move break the physical presence count and should be logged.

Timing UK tax against a calendar-year US return

This is where London-to-Zurich returns most often go wrong. UK tax for 2026/27 relates to income earned from April 2026 to the move. Most of that falls in US year 2026, but the liability is only finally settled when the UK return is filed in January 2028. Cash-basis filers claim foreign tax in the year it is paid. Accrual-basis filers claim it in the year it relates to. Most of our clients elect the accrual basis on Form 1116. The election is binding for later years, so the choice should be made deliberately. Under it, UK PAYE and the balancing payment for the UK part of 2026/27 attach to 2026 income, and any later adjustment from the final UK figure is corrected on an amended US return.

Which Swiss taxes are creditable, and which are not?

The US credit is available only for foreign income taxes, and only for amounts you are legally liable for and cannot recover. In Zurich the categories separate cleanly:

• Swiss federal direct tax on income is an income tax and is generally creditable.
• Zurich cantonal and communal income taxes, including the communal multiplier and any church tax levied as a surcharge on income tax, are income taxes and are generally creditable. Church tax has its own creditability questions and should be reviewed on the facts.
• Swiss withholding at source (Quellensteuer) on salary is a collection method for income tax and is creditable to the extent it is your final liability after any ordinary assessment.
• The annual cantonal and communal wealth tax is not an income tax. It is charged on net worth at 31 December, or at the end of liability, not on income or gains. It cannot be claimed on Form 1116 and generally produces no US deduction for an individual either. For a family with substantial securities or property this is often a five- or six-figure Swiss bill with no US relief.
• Swiss social security contributions (AHV/IV/EO) paid under the US-Swiss totalization agreement are not creditable income taxes.

Combined Swiss income tax in the city of Zurich, federal plus cantonal and communal, typically reaches the high thirties to around forty percent at the top margin. Rates and communal multipliers change each year and should be checked against current tables. Zurich wealth tax rates are a fraction of one percent per year on taxable net assets. They are low as a percentage but significant in amount for a wealthy household.

Swiss withholding tax on dividends and interest

Switzerland levies a 35% federal withholding tax (Verrechnungssteuer) on Swiss-source dividends and certain bank interest. How it interacts with the US return depends on where you lived when the dividend was paid:

• While resident in London, Swiss dividends suffer 35% withholding, and the excess over the treaty rate (generally 15% for portfolio holders) is reclaimed from the Swiss Federal Tax Administration under the applicable treaty. Only the tax you finally bear after the reclaim counts as creditable. Crediting the full 35% overstates the credit.
• Once resident in Zurich, a Swiss resident who declares the income on the Swiss return generally recovers the withholding in full, by refund or offset against Swiss tax. A fully recoverable tax is not a creditable foreign tax for US purposes. The creditable amount is the cantonal and federal income tax actually charged on the dividend through the ordinary assessment.

Undeclared Swiss-source income forfeits the Swiss refund. It is also a US reporting problem, because the income still belongs on the 1040.

Capital gains: the Swiss gap

Switzerland generally does not tax private capital gains on movable assets held by individuals who are not classed as professional securities dealers. The US taxes them in full. A US citizen who sells shares after arriving in Zurich will usually pay US tax with no Swiss tax to credit. Gains realised during the London part of the year, by contrast, may carry UK capital gains tax that can be credited. Recording the date of each disposal against the split date is therefore essential.

UK vs US vs Switzerland: the move year at a glance

Issue	UK (HMRC)	US (IRS)	Switzerland (Zurich)
Tax year	6 April to 5 April	Calendar year	Calendar year, liability from arrival
Basis of tax	Residence (SRT), split year on departure	Citizenship, worldwide, full year	Residence from arrival; earned income often taxed at an annualised rate
Main return	SA100 with SA109, due 31 January after year end	Form 1040, due 15 April (15 June if abroad), extendable to 15 October	Cantonal return, or Quellensteuer with ordinary assessment
Double tax relief	Split year removes overseas part	Form 1116 credit (or Form 2555 exclusion)	Treaty relief on foreign-source items
Wealth tax	None	None; foreign wealth tax not creditable	Annual cantonal and communal tax on net assets
Private capital gains	CGT while resident	Taxable	Generally exempt for private investors
Account reporting	Via return and CRS exchange	FBAR and Form 8938	Securities and assets list on the return

Step 3: FBAR and Form 8938 for UK and Swiss accounts

The move year usually produces the longest account list a client has ever reported. The UK current account, savings, ISA and brokerage accounts are often still open while the new Swiss bank, custody and brokerage relationships begin. All of them belong on the information returns.

FBAR

An FBAR is required if the combined maximum balances of all foreign financial accounts exceed $10,000 at any time in the year. That threshold is crossed almost immediately in a move year. Each account is reported at its maximum value, including accounts closed during the year and accounts with signature authority only (such as a company account in either country). The FBAR is filed separately with FinCEN, is due 15 April and is automatically extended to 15 October.

Form 8938

Form 8938 uses higher thresholds for taxpayers living abroad: for a single filer, more than $200,000 at year end or $300,000 at any time; for married couples filing jointly, $400,000 and $600,000. To use these thresholds you must meet the bona fide residence or physical presence test, which a London-to-Zurich mover usually does. Form 8938 also covers assets the FBAR does not, such as directly held foreign securities and certain interests in foreign entities. Overlap between the two forms is expected. Omission from either is not. Penalties for non-wilful FBAR failures can be significant per year. Our FBAR penalty calculator shows the exposure if earlier years were missed.

PFICs in both countries

UK unit trusts and OEICs, investment trusts held through an ISA, and Swiss collective investment funds are usually passive foreign investment companies for US purposes. Each needs Form 8621 every year, and the default PFIC regime can be punitive. The UK ISA wrapper gives no US shelter, and Swiss fund distributions do not change the PFIC analysis. Where a client has not filed Form 8621 for past London years, the departure year is a natural point to catch up.

What usually goes wrong on London-to-Zurich returns?

• Crediting wealth tax. Swiss wealth tax is put on Form 1116 as though it were income tax, which overstates the credit and invites an IRS adjustment.
• Crediting refundable withholding. The full 35% Swiss Verrechnungssteuer is claimed when most or all of it was recovered.
• Mismatched bonus apportionment. A London-earned bonus paid after the move is treated as UK income on one return and Swiss or unapportioned income on another.
• Ignoring the Swiss assessment lag. Swiss ordinary assessments can arrive well after the US return is filed. When the final Swiss figure differs from the provisional one, the US foreign tax credit must be redetermined and, where it falls, the IRS notified on an amended return.
• Losing split-year treatment. Too many UK workdays after departure, or keeping a London home available, makes the expected case fail and leaves Swiss salary taxable in the UK.
• Forgetting UK accounts. UK accounts left open after the move drop off the FBAR because the client now thinks of themselves as Swiss.
• Currency inconsistency. Different exchange-rate methods are used for income and for tax paid, which distorts the Form 1116 limitation.

Records to keep for the move year

A well-documented move year makes the UK, US and Swiss returns quicker to prepare and much easier to defend. We ask clients to keep:

• A day-count and workday diary for the full UK tax year and US calendar year, with flight records, showing UK, Swiss, US and other days.
• The UK employment contract, termination or transfer letter, P45, P60, P11D and the Swiss employment contract with the start date.
• Evidence of the London home's status after departure: lease end, sale completion or letting agreement.
• The Zurich commune registration (Anmeldung) confirmation and residence permit, which fix the Swiss start date.
• Swiss salary certificates (Lohnausweis), Quellensteuer statements, provisional and final cantonal and federal assessments, and wealth tax assessments.
• UK and Swiss bank and broker statements showing the maximum balance of every account in the year, and year-end valuations.
• Dividend vouchers showing Swiss withholding, plus any treaty reclaim filings and refund confirmations.
• Bonus and equity award documents showing grant, vesting and the service period, for apportionment between London and Zurich.
• Exchange-rate workings used for GBP and CHF conversions.

Keep these for at least as long as the relevant tax authority can open an enquiry or assessment. For US purposes that period is extended where foreign tax credits are carried forward or information returns are incomplete.

What if earlier years were missed?

A move often brings old gaps to light. A Swiss bank's onboarding questions about US status, or a first conversation with a cross-border preparer, can reveal unfiled FBARs, missing Forms 8938 or 8621, or UK income that never reached a US return. Where the failure was non-wilful, the IRS Streamlined Foreign Offshore Procedures generally allow three years of amended or late returns and six years of FBARs with no Title 26 miscellaneous offshore penalty for those who meet the non-residency test. Our streamlined filing specialists prepare the catch-up together with the move-year returns, so the history and the current year are consistent.

Our preparation sequence for a London-to-Zurich year

1. Fix the dates. Establish the UK split date, the Swiss arrival date and the US day-count before any figures are entered.
2. Apportion earnings. Divide salary, bonus and equity income between the London and Zurich periods on a basis that both the UK and US returns can use.
3. Prepare the UK final return with the split-year claim, so the UK liability is known.
4. Classify Swiss taxes as creditable income tax, recoverable withholding or non-creditable wealth tax.
5. Build Form 1116 by category, applying the accrual election and consistent exchange rates, and decide FTC against FEIE with the five-year revocation rule in view.
6. Compile FBAR, Form 8938 and Form 8621 from statements in both countries.
7. Diary the follow-ups: the Swiss final assessment, any treaty reclaim and any US amendment they trigger.

Our high-net-worth clients usually have equity compensation, pooled funds and accounts in more than one Swiss bank. For them, that sequence keeps a three-country year under control.

Getting the departure year right

A London-to-Zurich move is the point where two mature tax systems, and one that taxes wealth as well as income, all apply to the same twelve months. Done carefully, the UK return closes cleanly with split-year treatment, Swiss income taxes offset the US liability on Zurich earnings, and the information returns give a complete, consistent picture of both countries' accounts. Done casually, it leaves overstated credits, missing accounts and a UK claim that cannot be supported. If you have moved, or are about to move, from London to Zurich, contact our cross-border team for a confidential consultation. We will review your dates, accounts and earnings and prepare the UK, US and supporting filings as one coordinated set.