Cross-border

Cross-border worker calendar 2027: all the key dates

October 2026·9 min read

Updated 23 October 2026.

When you live in France and work in Switzerland, deadlines come from both sides of the border: French income tax, Swiss tax at source, health insurance, URSSAF… and no authority sends you the full calendar. Here it is, month by month, for 2027.

Not all 2027 dates have been published yet. Where a date is missing, you'll find the usual period ("usually") and, as a guide, the 2026 date. Check the exact date with the organisation concerned every year: the official links are at the end of the article.

Before you start: which dates apply to you?

Not every date applies to everyone. Two questions are enough to sort them out:

Which canton do you work in? In the 8 cantons of the 1983 Franco-Swiss agreement (Bern, Solothurn, Basel-Stadt, Basel-Landschaft, Vaud, Valais, Neuchâtel, Jura), a cross-border worker who in principle returns to France every day is taxed in France, thanks to the 2041-AS certificate. In Geneva and the other cantons, tax is withheld at source in Switzerland. Either way, you declare your income in France.
Which health insurance did you choose? With LAMal (Swiss health insurance), watch the premiums in the autumn and the 30 November deadline. With French health insurance (often called "CMU frontalier"), the yearly declaration to URSSAF is what matters.

January

1 January — new LAMal premiums. The 2027 premiums apply. If you switched insurer in November, the new one covers you from this date.
Early January — URSSAF payment schedule (French health insurance). The schedule for the year's contribution appears in your online account on urssaf.fr, or arrives by post. You pay quarterly by default, or monthly if you choose monthly direct debit; each instalment is due on the last working day of the quarter or month.
Early 2027 — your employer reports your 2026 remote-work rate. This is new: every year, Swiss employers must send their canton's tax office a certificate showing the salary and remote-work rate of their employees who live in France. The first one covers 2026 and is due in early 2027; the data is then exchanged with France. No exact date is set at federal level ("at the beginning of the year"); Geneva says January 2027. Compare the reported rate with your own record: above 40% remote work over the calendar year (temporary assignments included, up to 10 days), the tax rules change.

March

31 March — last day to correct your 2026 Swiss tax at source. If you are taxed at source in Switzerland (in Geneva, in a canton outside the agreement, or in the 8 cantons without a 2041-AS certificate) and the amount withheld looks wrong, or if you are a "quasi-resident" (at least 90% of your household's worldwide gross income taxable in Switzerland) and want a subsequent ordinary assessment (TOU), your request must be sent by 31 March. In Geneva, this is the DRIS/TOU form (a TOU request must be renewed every year); without a request, the tax withheld becomes final. The 31 March deadline is set by federal law and applies in every canton; only the form differs from one canton to another.

April to June: your French tax return

April — online filing opens. The official 2027 dates will be announced in April (in 2026, the online service opened on 9 April). You declare your 2026 income, including your Swiss salary, on the 2047-SUISSE schedule: tick "CAS 1" if you are a cross-border worker under the 1983 agreement, otherwise "CAS 2A" or "CAS 2B".
8 cantons, from your second year — your salary certificate. Attach the "certificat de salaire pour la déclaration d'impôt" (salary certificate for the tax return) issued by your Swiss employer; if you file online, send it through the secure messaging of your tax account. This is what gets you the pre-filled 2041-ASK certificate in the autumn.
Late May to early June — filing deadline, usually staggered by département. As a guide, in 2026 (online filing): 21 May for départements 01 to 19 (including Ain), 28 May for départements 20 to 54 (including Doubs and Jura), 4 June for départements 55 to 976 (including Haut-Rhin and Haute-Savoie). Paper returns: 19 May.
With your return — your Swiss accounts. Every bank account held abroad must be declared every year on form 3916, at the same time as your income. An undeclared account means a €1,500 fine.

August

Mid-August — correct your return if needed. Once you have received your tax notice, you can still correct your return with the "Corriger ma déclaration en ligne" online service. In 2026, it was open from mid-August to mid-December.

September

September — new rate, new instalments. Your spring return sets a new withholding rate, applied from September. If you are taxed in France (8 cantons), your Swiss employer does not withhold French tax: you pay it in instalments debited on the 15th of each month, and the amount changes at this point. If you still owe tax for 2026, it is debited in one go in September (under €300) or in four instalments from September to December.
Late September — 2028 LAMal premiums announced. The Federal Office of Public Health (FOPH) announces the following year's premiums; those for insured people living in the European Union are published on priminfo.admin.ch (in 2026: announced on 29 September). Insurers set a different premium for each country: you pay the rate for France, not the one for the canton where you work.

October

Mid-October (usually) — yearly declaration to URSSAF, if you chose French health insurance. You declare online your income from the previous year, which is used to calculate the following year's contribution: in 2026, 2025 income for the 2027 contribution, by 14 October. Each person concerned files their own declaration. Without a declaration, the contribution is calculated on five times the French social security ceiling (€240,300 in 2026); a late declaration adds 10% to the basis of calculation.
Before 31 October — your new LAMal premium. Your insurer must tell you your 2028 premium before this date. This is the time to compare it with the other insurers that cover people living in France.
Autumn — the 2041-ASK arrives (8 cantons). If you ticked "CAS 1" on the 2047-SUISSE when filing online, a pre-filled 2041-ASK certificate is sent to your home, valid for the following year.

November

30 November — switching LAMal insurer. To switch insurer on 1 January, your cancellation must reach your current insurer by 30 November at the latest; the FOPH recommends sending it by registered post before 15 November. Sign up with the new insurer at the same time. Note: switching insurer does not mean switching system. The choice between LAMal and French health insurance remains final. All the details: LAMal 2027 premiums and switching insurer.

December

Before 1 January — the 2041-AS certificate (8 cantons). Every year, give your Swiss employer your tax residence certificate (a 2041-AS stamped by your French tax office, or the pre-filled 2041-ASK) before 1 January. Without it, your employer has to withhold tax at source. If the 2041-ASK no longer matches your situation (new employer, new address) or hasn't arrived, fill in a 2041-AS and have it stamped; don't leave it until the last minute.
Mid-December — last day for online corrections to your tax return (in 2026: mid-December).

All year round: deadlines triggered by an event

First job in Switzerland — 3 months to choose your health insurance. You have 3 months from your first day of work to choose between LAMal and French health insurance (the "Choix du système d'assurance maladie" form, completed by the CPAM and then handed to the canton where you work). If you don't choose, you are automatically enrolled in LAMal, and the choice is final. All the steps: what to do in your first 3 months.
New job in one of the 8 cantons — the 2041-AS before your first day. In the first year, the stamped certificate must be given to your employer before you start work.
Joining French health insurance — 20 days. If you have just been registered as a cross-border worker, declare your income to URSSAF within 20 days of registration.
Losing your job — register with France Travail straight away. France, your country of residence, pays your unemployment benefit. You have 12 months after the end of your contract to register, but benefit cannot start before you register, and a 7-day waiting period then applies: register as soon as your contract ends. The details: job loss in Switzerland when you live in France.

Official sources

Getting support

A calendar is useful — but you still need to know which dates apply to you, and to have the right documents ready at the right time.

I'm not a tax specialist or a lawyer, but as an administrative assistant specialising in supporting cross-border workers, I can help you identify the deadlines that apply to you, prepare your documents and make sure nothing slips through from one year to the next.

Want to review your deadlines? Book a free initial consultation — we'll plan your year together.

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