You live in France and work for a Luxembourg employer? Every day you work from home counts. Beyond a certain number of days, part of your salary becomes taxable in France, and your social security cover may change. Here is how the 34-day rule works, and the traps to avoid.
In short
- Tax: up to 34 days worked outside Luxembourg per year, your salary remains fully taxable in Luxembourg.
- On day 35: all days worked outside Luxembourg become taxable in France, from the very first one.
- Social security: a separate counter, expressed as a share of working time (25%, and up to under 50% under conditions).
- Tip: keep an accurate month-by-month record of your remote-working days.
Where does the 34-day rule come from?
As a principle, salary is taxed in the country where the work is physically performed. A cross-border worker working from home in France should therefore, in theory, be taxed in France for each day at home. To avoid this complexity, France and Luxembourg agreed a tolerance threshold in their tax treaty.
This threshold, long set at 29 days, was raised to 34 days per year by the amendment to the treaty signed on 7 November 2022, applicable to tax periods from 2023. As long as you stay below it, your salary is fully taxed in Luxembourg, as if you had worked every day on site.
Which days count towards the 34 days?
The counter covers working days spent outside Luxembourg: remote working from your home in France and, depending on the case, mission or training days spent in another country. A few practical rules:
- a half day of remote work counts as a full day;
- holidays, weekends, public holidays and sick leave do not count, since you are not working;
- for part-time work or if you start during the year, the threshold is reduced pro rata;
- the counter resets on 1 January: days are not carried over from one year to the next.
What happens if you exceed 34 days?
This is the most misunderstood point. Exceeding the threshold does not only affect the extra days: from day 35, all days worked outside Luxembourg become taxable in France, including the first 34.
In practice, the share of salary for those days is taxed in France and the rest in Luxembourg. This means two returns to adjust, tax instalments to pay in France and, often, a higher total tax bill. It may also cost you certain options in Luxembourg, such as being treated as a resident taxpayer, which requires at least 90% of your professional income to be taxable in Luxembourg.
Social security: a different counter
Do not confuse the tax rule with the social security rule. For social security, what matters is not a number of days but the share of your working time spent in your country of residence:
- under 25% remote work: you remain covered in Luxembourg;
- 25% to under 50%: you can remain covered in Luxembourg under the European framework agreement on cross-border telework, in force since 1 July 2023, provided an A1 certificate is requested;
- 50% or more: cover normally switches to France.
Example: two remote days a week represent 40% of working time. That is acceptable for social security under the framework agreement, but far beyond the 34 tax days over a year. Part of the salary will then be taxed in France.
Our practical tips
- Count from January: record every remote, mission and training day outside Luxembourg.
- Keep a margin: aim for 30 days rather than 34 to absorb the unexpected.
- Keep evidence: schedule approved by your employer, certificates, badge records, expense claims.
- Tell your employer if you are likely to exceed the threshold, so payroll and filings can be adjusted.
- Have your return checked: splitting taxable income between both countries and choosing the right options in Luxembourg can be worth several hundred euros.
Frequently asked questions
Does the 34-day rule also apply to Belgian and German cross-border workers?
No, each tax treaty sets its own threshold. The rules described here apply to French residents working for a Luxembourg employer.
Does a half day of remote work count?
Yes, a half day worked outside Luxembourg counts as a full day towards the 34 days.
If I exceed by a few days, are only those days taxed in France?
No. Beyond 34 days, all days worked outside Luxembourg become taxable in France, including the first 34.
Is the 34-day threshold the same for social security?
No. Social security looks at the share of working time: under 25%, or under 50% with the framework agreement and an A1 certificate.
Who can prepare my Luxembourg tax return?
A chartered accountant can calculate the split between France and Luxembourg, choose the most favourable options and file your return. At INFID Advisory, an individual return starts at €100 excl. VAT.
Have your situation checked
Getting close to 34 days, already over, or simply want to be sure nothing is missed? We prepare your Luxembourg tax return, for residents and cross-border workers, from €100 excl. VAT. Also check the 6 deductions people often forget. Any question? Contact us: the first conversation is free.
Updated on 8 November 2026. General information, not personal advice. Sources: amendment of 7 November 2022 to the France–Luxembourg tax treaty (impotsdirects.public.lu), European framework agreement on cross-border telework, Frontaliers Grand Est.
