Cross-border telework 40%: tax vs social threshold 2026

What are the two telework thresholds for cross-border workers in Switzerland?

For a cross-border worker who teleworks from their country of residence while keeping a job in Switzerland, two distinct thresholds apply simultaneously — one fiscal, one social — and they should not be confused. The 40% tax threshold comes from the amendment to the Swiss-French double taxation agreement signed on 27 June 2023, made permanent through an exchange of letters of 22 December 2023; it applies only to French cross-border workers in Switzerland. The 49.9% social security threshold (often rounded to "50%") comes from the multilateral framework agreement of 1 July 2023 on the application of Article 16 of Regulation (EC) No 883/2004; it applies to all EU/EFTA cross-border workers from signatory states.

A French cross-border worker teleworking part-time must therefore comply with both thresholds at the same time. Crossing the 40% tax threshold shifts the right to tax a fraction of the salary to the country of residence; crossing the 49.9% social security threshold shifts all social contributions to the country of residence. These are not the same effects, do not concern the same countries and do not have the same trigger points.

Calculate the net impact on your salary by canton with the Swiss net salary calculator — particularly useful if you are weighing whether to stay under the 40% tax threshold or not.

What exactly is the 40% tax threshold between France and Switzerland?

The tax threshold of 40% of annual working time allows a French-Swiss cross-border worker to telework from France without triggering a fiscal split between the two states or any change to their Swiss withholding tax regime. This threshold was set by the amendment to the Swiss-French double taxation agreement of 9 September 1966, signed in Paris on 27 June 2023 and provisionally applied since 30 June 2023. An exchange of letters of 22 December 2023 between the two administrations confirmed its permanent nature, replacing the COVID-era transitional regime that had expired on 31 December 2022.

In practical terms, the mechanism counts as "telework" all assignments performed from the employee's French home, including occasional business travel undertaken from France or to a third country. As long as the cumulative annual duration of these assignments remains at or below 40% of working time, the entire salary remains taxable in Switzerland under the regime applicable to the cross-border worker: withholding tax in cantons outside the 1983 agreement, or exclusive taxation in France for the eight cantons under the 1983 agreement (see below).

The 40% threshold is assessed over the calendar year, not on a monthly average. The French tax administration bulletin (BOFiP-Impôts INT-CVB-CHE-10-20-40, source available in French) clarifies that partial telework days count as full telework days if more than half of the day is spent at home. Conversely, sick leave and holidays are not included in the denominator.

Telework periods carried out from the State of residence, within a limit of 40% of working time, are deemed to be performed in the State where the employer is located.

— Amendment to the Swiss-French DTA, 27 June 2023 (extract from the official communiqué)

Which Swiss cantons fall under the 1983 cross-border agreement with France?

Eight Swiss cantons apply the Swiss-French agreement of 11 April 1983 on the taxation of remuneration of cross-border workers: Bern, Solothurn, Basel-Stadt, Basel-Landschaft, Vaud, Valais, Neuchâtel and Jura. In these eight cantons, the French cross-border worker's salary is taxed exclusively in France, and Switzerland receives in return a flat compensation of 4.5% of the gross payroll of the cross-border workers concerned (Art. 2 of the 1983 agreement). No withholding tax is deducted in Switzerland on the pay slip of these cross-border workers.

Geneva is not part of the 1983 agreement. The canton applies a separate regime: it withholds tax at source in Switzerland (Art. 83 et seq. DBG/LIFD and Geneva cantonal scales) and transfers 3.5% of the payroll to the French departments of Ain (01) and Haute-Savoie (74). For the Geneva cross-border worker, the salary is therefore Swiss-taxed at source; France only taxes the portion of worldwide income exceeding the threshold deduction (French annex 2047-Suisse).

The 40% threshold of the 2023 amendment applies to both regimes simultaneously: whether the cross-border worker falls under the 1983 agreement or the general DTA regime, crossing 40% triggers a transfer of taxation to France for the excess share. The practical difference lies in the withholding mechanism: workers under the 1983 agreement must notify their employer of the threshold breach to trigger a retroactive withholding, while DTA workers must declare the French share in addition to their Swiss taxation.

For the monthly withholding mechanics on a Swiss pay slip, see the detailed line-by-line breakdown of a Swiss pay slip — which covers the "Withholding tax" line and its canton-specific application.

How does the 50% EU/EFTA social security threshold differ from the tax threshold?

The 49.9% social security threshold stems from a distinct legal instrument: the multilateral framework agreement on the application of Article 16(1) of Regulation (EC) No 883/2004, concluded under the auspices of the Administrative Commission for the Coordination of Social Security Systems and entered into force on 1 July 2023. It exclusively concerns social security (AHV-IV-EO / OASI-DI-LEC, ALV / unemployment insurance, BVG / occupational pensions, UVG / accident insurance, family allowances) and has no fiscal effect whatsoever. Geographically, it covers all EU/EFTA states that have signed: Switzerland, Germany, Austria, Liechtenstein, Belgium, France, Italy, Luxembourg, the Netherlands, Poland, Czech Republic, Slovakia, Slovenia, Finland, Norway, Spain, Portugal, Croatia, Malta (consolidated list maintained by the FSIO).

Under the ordinary rule (Art. 13 of Regulation 883/2004), an employee performing at least 25% of their activity in their state of residence is fully subject to the social security system of that state — a rule that would have heavily penalised cross-border telework after the end of the COVID exception. The framework agreement of 1.7.2023 introduces a derogation under Art. 16 of Regulation 883/2004: as long as telework in the state of residence remains strictly below 50% of total working time, the worker remains fully subject to social security in the employer's state. The application is filed by the employer through the ALPS portal in Switzerland (Anwendbare Sozialversicherungsgesetzgebung – Plattform Schweiz) and leads to the issuance of an A1 certificate valid for up to 3 years.

Two crucial points to understand. First, the social security threshold does not trigger at 40% like the tax threshold: a French cross-border worker teleworking 45% of the time from France remains socially Swiss (under the framework agreement) but switches fiscally to France for the share beyond 40%. Second, the framework agreement requires an active step: without an explicit A1 certificate, the default rule kicks in automatically as soon as 25% of activity in the state of residence is exceeded — whereas in practice many cross-border teleworkers are unaware that the application must be filed.

Which rules apply to German, Italian and Austrian cross-border workers?

Three other cross-border profiles operate under specific rules that differ from the French case. For all of them, the 49.9% social security threshold from the framework agreement applies, provided the state of residence has signed the framework agreement of 1.7.2023 (which is the case for Germany, Italy, Austria and Liechtenstein, among others). On the tax side, however, each bilateral relationship has its own architecture.

German cross-border worker (DE-CH): the Swiss-German double taxation agreement of 11 August 1971, Art. 15a, defines a "Grenzgänger" status conditional on daily return home. A Grenzgänger who fails to return home on more than 60 days per calendar year loses this status and falls back into the general DTA regime. On the telework front, a consultation agreement (Konsultationsvereinbarung) of 6 April 2023 between Germany and Switzerland specifies that telework days from Germany count as non-return days, except under temporary arrangements; the practical telework margin is therefore much narrower than with France (≤ 60 days/year ≈ 23% of full-time work, instead of 40%).

Italian cross-border worker (IT-CH): a new agreement signed on 23 December 2020 and entered into force on 17 July 2023 (SR 0.642.945.41) redefines the tax regime for Italian cross-border workers. A new category distinguishes between "new cross-border workers" (first Swiss job from 17.7.2023, taxed 80% in Switzerland + 20% in Italy after credit) and "old cross-border workers" (before that date, transitional regime of exclusive Swiss taxation until 31.12.2033). A specific protocol on telework signed on 6 May 2024 allows up to 25% telework from Italy without losing cross-border worker status — a more restrictive threshold than the French 40%.

Austrian cross-border worker (AT-CH): the Swiss-Austrian DTA of 30 January 1974 also provides for a cross-border worker status with daily return and a 45-days-of-non-return rule. No dedicated telework amendment has been signed to date, leaving AT-CH cross-border workers in a less favourable regime than their French counterparts: regular telework from Austria can cause loss of cross-border worker status beyond 45 days per year.

Non-signatory special case: not all EU states have joined the framework agreement of 1.7.2023. As of 1 January 2026, non-signatory states include in particular Bulgaria, Greece, Romania, Cyprus, Ireland, Denmark and Estonia (list to be verified). For a cross-border worker residing in one of these states, the 25% social threshold of the default rule (Art. 13 Reg. 883/2004) is the only one applicable: 5 telework days per month are enough to shift the full social security liability to the country of residence.

What happens if I exceed 40% telework (tax threshold)?

Crossing the 40% tax threshold does not cause loss of cross-border worker status or the G permit, but it splits the taxation of the salary between the two states pro rata to the days worked in France versus Switzerland. Mechanically, the salary share corresponding to telework days in France above the threshold becomes taxable in France, while the "Swiss days" share remains taxable in Switzerland under the applicable regime (withholding tax under the general DTA regime, or exclusive French taxation under the 1983 agreement).

Practical consequences by canton:

• Geneva cross-border worker (DTA regime) exceeding 40%: the employer continues to withhold the Swiss withholding tax on 100% of the salary (they cannot know in real time which days are telework days), but the employee must declare the excess fraction in France and use a French tax credit to neutralise double taxation. Risk: under-declaration in France and reassessment by the DGFIP. The French tax administration has published a Form 2047-Suisse (source available in French) for declaring this fraction.
• 1983 agreement cross-border worker (Vaud, Bern, etc.) exceeding 40%: the excess share remains taxable in France (where it already is at 100%), but the attribution becomes more complex when the employee occasionally works in a third country — the agreement then provides for a sharing mechanism.

On the social security side, exceeding the 40% tax threshold has no effect as long as the 49.9% threshold is not crossed: AHV/OASI, ALV/UI, UVG/accident and BVG/pension contributions continue to be deducted normally on the Swiss pay slip, and the A1 certificate retains its validity.

To anticipate the net impact on your take-home pay if you adjust your telework ratio, the Nsix Talent Swiss net salary calculator compares the regimes by canton at equivalent gross salary.

What happens if I exceed 50% telework (social security threshold)?

Crossing the 49.9% social security threshold triggers the complete transfer of social security liability to the country of residence, in strict application of Art. 13 of Regulation 883/2004. The A1 certificate issued under the framework agreement becomes void, and the Swiss employer must stop deducting AHV, ALV, UVG and BVG contributions on the pay slip. The employer instead becomes liable for the social contributions of the country of residence on the full salary — for example, for an employer of a French cross-border worker, registration with the Centre national des firmes étrangères (CNFE) in Strasbourg and application of the URSSAF rates (approximately 42% employer contributions on gross salary).

The impact on net pay is substantial and asymmetric:

1. Swiss employer side: additional French social contributions (approximately 42% versus approximately 12% on the Swiss side), which erode the margin or force a salary renegotiation. Many companies impose a contractual non-crossing clause on the 49.9% threshold to avoid this administrative shift.
2. Employee side: loss of the Swiss BVG pension regime, switch to the French pay-as-you-go retirement system plus mandatory complementary schemes (Agirc-Arrco), loss of Swiss OASI accrual — except under coordination arrangements. The retirement coverage deteriorates as a result.

Good practice: where telework levels may fluctuate during the year, some employers activate a 51% minimum physical presence rule in Switzerland in the employment contract, to absorb high-telework weeks (holidays, business trips). This contractual buffer is the conservative approach recommended by cantonal practice in Geneva and Vaud.

What happens if I exceed BOTH thresholds at the same time?

Crossing both thresholds simultaneously — 40% fiscal and 49.9% social — triggers both consequences cumulatively: (a) salary split between Switzerland and France pro rata to working days, (b) full social security transfer to France. The employee becomes both taxable in France for the share above 40% and fully affiliated with the French social security system. The Swiss employer must then run in parallel a split tax calculation and a full French social registration.

Practically, as soon as the 50% telework mark is approached, the administrative jump is not linear: moving from 49% to 50% has a far more radical effect than moving from 30% to 40%, because the all-or-nothing social threshold neutralises the fiscal advantage of telework beyond.

Practical recommendation: for those who want to maximise telework while securing their regime, aiming at a firm 40% (which respects both thresholds, fiscal and social) is the optimum in the vast majority of cases. Beyond that, the trade-off becomes a wider HR matter (company policy, comparative taxation, retirement coverage) which goes beyond the informational scope of this guide and warrants advice from a cross-border specialised fiduciary.

How does the employer trigger the A1 certificate for cross-border telework?

The A1 certificate is the official document that evidences the framework agreement derogation to both social security authorities (Swiss and foreign). The application must be filed by the employer — the employee cannot file it alone. On the Swiss side, the procedure goes through the ALPS platform of the Federal Social Insurance Office, which forwards the application to the relevant AHV compensation fund and issues the certificate within 2 to 6 weeks depending on the canton.

The "framework agreement" A1 certificate has three specifics compared to the classic "secondment" A1:

• Validity up to 3 years renewable (secondment A1 is capped at 24 months)
• Specific reference on the document: "Derogation under Article 16 Regulation 883/2004 — multilateral framework agreement on telework"
• Joint application by employee and employer required: the form (A1 application) must be signed by both parties
• Signatory states only: if the employee's country of residence has not signed the framework agreement, the classic A1 derogation remains theoretically available but subject to a discretionary bilateral agreement by the FSIO, which is slower and more uncertain

Without an A1 certificate, the legal risk does not lie only with the employee: the Swiss employer faces, in the event of a URSSAF audit (for a French teleworker), a reassessment of contributions on the entire concerned payroll, plus interest and penalties. For this reason, some companies require, at the onboarding of a cross-border worker, the prior production of the A1 certificate or the signature of a telework policy that explicitly caps the share at 40%.

Frequently asked questions

Do business trips count towards the 40% telework calculation?

Yes. Under the mechanism set by the amendment to the Swiss-French DTA of 27 June 2023, assignments performed from the French home or business travel undertaken from France (and to a third country) are treated as telework for the tax threshold. Business travel to Switzerland from the French home is not counted (Swiss working days).

If I telework 40% from France, can my employer still withhold tax on 100% of my salary?

Is the 40% threshold calculated on the calendar year or on a rolling year?

Can my employer refuse to apply for an A1 telework certificate for me?

What about a French cross-border worker teleworking 30% from France and 15% from a third country during holidays?

Does the 40% threshold also apply to Geneva cross-border workers under Swiss withholding tax?

If I have been an Italian cross-border worker since 2020, does the new 25% telework threshold apply to me?

Do I need an A1 certificate if I telework less than 25%?

What if my employer accidentally exceeds the 50% social threshold without realising it?

Will the 40% threshold continue to apply after 2026?