Which Double Taxation Agreements Are Especially Relevant for Expats?

Expats in Switzerland are frequently subject to income or wealth tax in more than one country. To prevent double taxation, Switzerland has concluded double taxation treaties (DTTs) with over 100 states. This article explains how DTTs work, which treaties are most relevant for the most common countries of origin, and what expats need to pay particular attention to in practice.

Important note: This article is for general information purposes only (as of 2025/2026). DTT rules are complex and subject to ongoing change. We recommend professional tax advice for your individual situation.

What is a Double Taxation Treaty?

Basic Principle and Purpose

A DTT is a treaty under international law between two states. It determines which state has the right to tax specific types of income and assets when a person has tax connections in both contracting states. The aim is to prevent the same income from being fully taxed twice.

DTTs typically cover:

• Employment income: The activity-state principle (taxation where work is performed); frontier worker rules as a key exception
• Self-employment income: Depends on whether a "permanent establishment" exists in the other state
• Dividends, interest and royalties: Source-state withholding tax, but capped at a maximum rate agreed in the DTT (residual tax)
• Real estate: The right to tax always belongs to the state where the property is located
• Pensions and retirement benefits: Depending on the treaty, taxed in the state of residence or the source state; public-service pensions often follow separate rules

Methods for Eliminating Double Taxation

DTTs use two main methods:

MethodHow it worksTypical applicationExemption methodForeign income is exempt from tax in the state of residence, but used rate-determinatively (progression clause)Common for employment incomeCredit methodTax paid abroad is credited against the tax liability in the state of residenceCommon for capital income; US treatyMixed formsDifferent methods applied depending on income typeMost modern treaties

The Most Important DTTs for Expats in Switzerland

Germany

The Switzerland–Germany DTT (SR 0.672.913.62) is the most widely applied treaty and is of central importance for the approximately 65,000 German frontier workers as well as many Germans resident in Switzerland.

Key rules:

• Employment income: Taxed in the state where the work is performed (Switzerland), unless the frontier worker rule applies
• Frontier worker rule (Art. 15a DTT): If someone lives in Germany and works in Switzerland, Germany retains the right to tax – Switzerland levies only a 4.5% withholding tax on gross salary, which is credited against German income tax
• Requirements for frontier worker status: (1) Regular return to the place of residence in Germany; (2) no more than 60 non-return days per year for professional reasons; (3) submission of a certificate of residence (Form Gre-1 / Gre-2)
• Real estate in Germany: Rental income taxed in Germany; Switzerland exempts it subject to the progression clause
• Private pensions: Generally taxed in the state of residence; public-service pensions subject to separate rules

Important change – amending protocol in force from 1 January 2026:

The amending protocol to the Switzerland–Germany DTT (signed 21 August 2023) entered into force on 27 November 2025 and applies from 1 January 2026. Key changes:

• New frontier worker definition: Employees must now commute to work on at least 20% of agreed working days (relative rule, replacing a fixed minimum number of days) – better adapted to part-time workers
• Simplified mutual agreement procedure: It is now possible to file a revision request in Switzerland directly, without initiating a formal mutual agreement procedure first
• Dividends from qualifying holdings (10% or more): Remain exempt from withholding tax; holding period now precisely defined as a "period of 365 days"
• BEPS minimum standards: New anti-abuse clauses; Principal Purpose Test (PPT) introduced

France

The Switzerland–France DTT (SR 0.672.934.91) contains two separate sets of rules whose application depends on the place of work.

1. Frontier worker agreement of 11 April 1983

Applies exclusively to the eight Swiss border cantons: Berne, Solothurn, Basel-City, Basel-Country, Vaud, Valais, Neuchâtel and Jura.

• French frontier workers employed in one of these cantons who return to their place of residence in France on a daily basis are taxed in France (not in Switzerland)
• Switzerland levies no withholding tax but receives a compensation payment of 4.5% of gross remuneration from France
• For frontier workers in other cantons (e.g. Geneva, Aargau, Zurich) this special rule does not apply – they are subject to Swiss withholding tax at source

2. General DTT of 9 September 1966

• Covers all other cases (non-frontier workers, capital income, real estate)
• For employees outside the frontier worker zone: activity-state principle (taxation in Switzerland); 183-day rule for short assignments

Important changes 2025/2026:

• Telework permanently regulated (from 1 January 2026): The supplementary agreement on telework taxation entered into force on 24 July 2025 and applies from 1 January 2026. French frontier workers may perform up to 40% of their working time as telework/home office without losing their frontier worker status or changing their tax treatment. The right to tax these home-office days remains with the employer's state of domicile (Switzerland)
• New documentation obligations from 1 January 2025: Employers must provide, on request, a certificate covering telework days, travel days in third countries and non-return days
• Automatic information exchange from 2027: Wage data for the 2026 tax year will for the first time be automatically exchanged between Switzerland and France

USA

The Switzerland–USA DTT (SR 0.672.933.61; last amending protocol in force since 20 September 2019) is the most complex treaty covered here.

Special feature – US citizenship-based taxation:

The United States and Eritrea are the only countries in the world that tax their citizens worldwide and regardless of residence ("citizenship-based taxation"). A US citizen in Switzerland is simultaneously subject to unlimited tax liability in Switzerland (based on residence) and in the USA (based on citizenship). The DTT helps reduce double taxation but cannot eliminate it entirely.

Key rules:

• Employment income: Credit method – Swiss taxes paid are credited against US tax liability; the Foreign Earned Income Exclusion (FEIE) may also be available
• Dividends: Swiss withholding tax (35%) capped at 15% under the DTT (0% for qualifying holdings of 10% or more)
• Interest: Withholding tax in the source state generally exempt for beneficial owners resident in the other state
• Pensions: Taxed in the state of residence as a rule; exception: Swiss occupational pension fund (2nd pillar / Pensionskasse) is not a qualified retirement plan for US purposes – employer contributions and earnings may be currently taxable in the USA

FATCA and reporting obligations:

• FBAR (FinCEN Form 114): US persons with foreign accounts exceeding USD 10,000 (in aggregate) must file an FBAR annually; deadline 15 April (extendable to 15 October)
• FATCA Form 8938: Additional reporting obligation for foreign financial assets exceeding USD 50,000 (singles living abroad)
• New FATCA model under preparation: In March 2025 the Federal Council launched a consultation on switching from FATCA Model 2 (one-way) to Model 1 (reciprocal automatic exchange); implementation expected around 2027
• "Accidental Americans": Persons who hold US citizenship unintentionally (e.g. born in the USA) are also subject to worldwide US tax liability; the IRS "Streamlined Foreign Offshore Procedure" allows penalty-reduced catch-up filings

US tax year and deadlines:

• Tax year = calendar year (same as Switzerland)
• US tax return filing deadline: 15 April (automatic extension to 15 June for residents abroad; further extension to 15 October available on request)

Italy

The Switzerland–Italy DTT (SR 0.672.945.41) contains a special frontier worker rule for the border zone.

Frontier worker rule Switzerland–Italy:

• Applies to persons resident in the Italian border zone working in the Swiss border cantons (Graubünden, Ticino, Valais)
• Taxation in the state of residence (Italy); Switzerland levies a withholding tax, part of which is transferred to the affected border cantons as compensation
• Ticino particularity: Given the historical ties, specific cantonal rules apply for Ticino frontier workers

Further key points:

• Dividends from Switzerland: Swiss withholding tax (35%) reduced to 15% under the DTT
• Social security: The DTT covers tax issues only; for EU citizens, social security coverage is governed by EU coordination regulations

United Kingdom (UK)

The Switzerland–UK DTT (SR 0.672.936.7) is a bilateral agreement independent of the EU and was not changed by Brexit.

Key rules:

• Employment income: Activity-state principle; 183-day rule (for short assignments with employer not based in the work state, the residence state retains taxation rights)
• Real estate in the UK: Rental income taxed in the UK; Switzerland exempts it subject to the progression clause
• Private pensions / occupational pensions from the UK: Taxed in the state of residence (Switzerland)
• UK public service pensions: Taxed in the source state (UK)
• UK dividends: Withholding tax in the UK capped at 15%

Post-Brexit: The DTT and its protections remained fully intact. Switzerland concluded new bilateral agreements with the UK for other areas (social security, freedom of movement, financial services) under its "Mind the gap" strategy, effective 1 January 2021.

Taxation of Various Income Types

Employment Income

The activity-state principle is the basic rule: employment income is taxed where the work is physically performed.

• Exceptions: Frontier worker rules (DE, FR, IT) and the 183-day rule (for short stays in the work state, the residence state may retain taxation rights if employer and salary payment are not based in the work state)
• Home office: Working days spent in the state of residence generally create a taxable nexus there – particularly relevant for frontier workers and expats with international employers

Self-Employment and Permanent Establishment

• Taxed in the state of residence, unless a fixed place of business (permanent establishment) exists in the other state
• Expats with advisory activities, international mandates or clients abroad should carefully assess whether they are inadvertently creating a permanent establishment

Capital Income

Income typeBasic ruleTypical DTT reductionDividendsSource state levies withholding taxReduced to 15% or 0%InterestOften residence state onlyWithholding tax often 0%RoyaltiesOften residence state onlyWithholding tax 0%–10%

Note: The Swiss withholding tax (35%) is capped at the applicable residual rate under the relevant DTT; the difference is refunded on request.

Real Estate

• Properties are always taxed in the state where they are located – for rental income, wealth tax and capital gains
• The other state takes these into account rate-determinatively (progression clause) only

Pensions and Retirement Benefits

Pension typeTypical taxation rulePrivate pension / occupational pensionState of residence (Switzerland)Public-service pensionSource state (country of origin)AHV/IV (Swiss state pension)State of residenceUS Social SecurityWhen resident in Switzerland: Switzerland taxesOccupational pension (2nd pillar) for US personsComplex US-specific rules; ongoing tax liability possible

Practical Examples

Example 1: German Frontier Worker in Zurich

Mr Müller lives in Constance (Germany) and works in Zurich. He returns home daily and spent 25 nights in Switzerland during 2025 for professional reasons.

• Status: Frontier worker under Art. 15a DTT CH–DE (fewer than 60 non-return days; Gre-1 in place)
• Taxation: Germany taxes all employment income; Switzerland retains 4.5% withholding tax, credited against German income tax
• Obligations: Obtain Form Gre-1 from the tax office and submit to Swiss employer; annual German tax return with Annex N-Gre; deadline 31 July of the following year
• From 2026: New frontier worker definition (20% rule instead of absolute number of days) applies

Example 2: American Expat in Geneva

Ms Johnson is a US citizen working for an international company in Geneva. She also receives dividends from US equities (USD 15,000 p.a.).

• Swiss tax liability: Unlimited (resident); entire worldwide income must be declared
• US tax liability: Unlimited (citizenship); annual IRS tax return required
• Employment income: Taxed in Switzerland; credited against US tax liability; FEIE may be applicable
• Dividends: USA levies 15% withholding tax on US dividends; Switzerland takes into account and credits
• FBAR: Swiss accounts exceeding USD 10,000 must be reported by 15 April

Example 3: British Retiree in Zug

Mr Thompson retires from London and moves to Canton Zug. He receives: (a) a private occupational pension (CHF 40,000 p.a.) and (b) the UK State Pension (CHF 15,000 p.a.).

• Private occupational pension: Taxed in Switzerland (state of residence); UK waives taxation
• UK State Pension: Taxed in Switzerland (state of residence)
• Dividends from UK shares: Max. 15% withholding tax in the UK, remainder refunded; taxed in Switzerland
• UK property rented out: Rental income taxed in the UK; Switzerland takes into account rate-determinatively

Common Mistakes and Tips

Common Mistakes

• DTT not actively claimed: DTT benefits do not arise automatically – forms must be submitted, applications filed, deadlines observed
• Missing certificate of residence: Without Form Gre-1 / Gre-2, the Swiss employer applies the full withholding tax rate instead of 4.5%
• Home-office days not documented: Unreported home-office days can trigger unexpected tax liability in the state of residence – keep a daily calendar
• US tax liability overlooked: "Accidental Americans" and green-card holders are often surprised to find they remain US-taxable without ever having lived there
• 2nd pillar pension treated incorrectly for US persons: Employer contributions and earnings may be currently taxable in the USA – consult a specialist US tax advisor early
• Different tax year deadlines ignored: Switzerland and the USA both use the calendar year, but filing deadlines and submission procedures differ significantly

Tips

• Clarify before moving: Check at an early stage whether a DTT exists, which method it applies, and which documents are required
• Obtain certificate of residence in good time: Apply at the competent tax authority in your state of residence
• Keep a home-office calendar: Daily records of work location are essential for cross-border employment
• Use the mutual agreement procedure: If double taxation persists despite the DTT, a Mutual Agreement Procedure can be requested from the Swiss State Secretariat for International Finance SIF (dba@sif.admin.ch)
• Claim withholding tax refunds: Overpaid foreign withholding taxes can be reclaimed using ESTV forms – observe deadlines
• Use official sources: estv.admin.ch and sif.admin.ch are the most reliable sources for current DTT texts and forms
• Seek professional advice: For multiple tax liabilities, shareholdings, foreign pensions or real estate, consult a specialist in international tax law

Conclusion

Double taxation treaties are an indispensable tool for expats in Switzerland. They determine which state may tax which income and prevent double burdens. Switzerland has DTTs with over 100 countries – particularly relevant for expats are those with Germany (frontier workers; changes from 1.1.2026), France (frontier worker zone; home-office rules from 1.1.2026), the USA (citizenship-based taxation; FATCA), Italy (Ticino frontier zone) and the United Kingdom (unchanged after Brexit). DTTs must be actively claimed, require the right documents, and are subject to ongoing change. Those who are well-informed, declare income correctly, and seek expert advice where needed benefit from significant tax advantages and avoid costly mistakes.