Residents of France, Belgium and Germany who work for a Luxembourg employer can work up to 34 days a year outside Luxembourg, at home or in third countries, and stay fully taxable in Luxembourg. For social security, telework below 25% of working time changes nothing, and between 25% and 49% the employee can stay insured in Luxembourg under the EU framework agreement with an A1 certificate. Above the limits, the residence country taxes or insures, and the employer may need payroll there.
Two counters, two thresholds: tax days and social security time
A large share of the people who work in Luxembourg cross the border every morning from France, Belgium or Germany. Their salary is taxed in Luxembourg and they are insured in the Luxembourg social security system, as long as they actually work in Luxembourg. Every day they work from home, or on a mission in another country, chips away at that rule.
Two separate tests apply, and they count different things. For income tax, each treaty allows a tolerance of 34 days a year worked outside Luxembourg before the country of residence can tax the salary for those days. For social security, the test is a share of working time: below 25% at home, nothing changes; between 25% and 49%, the employer and employee can keep Luxembourg social security under an EU framework agreement; at 50% or more, the employee moves to the social security system of the country where they live.
Crossing either line is not illegal. It means more paperwork, sometimes more tax, and for the employer a payroll obligation in a second country. This guide explains both counters, what counts as a day, what happens when you exceed them and what employers should set up, with examples for France, Belgium and Germany and a checker for your own situation.
34 days
A year outside Luxembourg, for FR, BE and DE.
Under 25%
Normal EU rule: Luxembourg system.
Up to 49%
Telework only, with an A1 certificate.
Track every day
Payroll, A1 and permanent establishment risk.
The 34-day tolerance in the three treaties
Under the tax treaties between Luxembourg and its neighbours, a salary is taxed where the work is physically performed. A day worked at home in Metz, Arlon or Trier is, in principle, taxable in France, Belgium or Germany. Because that would make every payslip a two-country calculation, each treaty now contains a tolerance: if the days worked outside Luxembourg do not exceed 34 in a calendar year, Luxembourg keeps the right to tax the whole salary.
The figure has been the same for all three countries since 2024, but it arrived by different routes and the counting rules differ in detail.
| Residence | Tolerance | In force since | Legal basis |
|---|---|---|---|
| France | 34 days | Tax year 2023 (29 days before) | Amendment to the 2018 treaty signed on 7 November 2022, approved by the Luxembourg parliament on 3 May 2023 |
| Belgium | 34 days | Tax year 2022 (24 days before) | Amendment to the 1970 treaty signed on 31 August 2021 |
| Germany | 34 days | 1 January 2024 (19 days before) | Protocol of 6 July 2023 amending the 2012 treaty, new Article 14(1a), and a consultation agreement on its application |
The tolerance covers days worked in the country of residence and days worked in third countries together. A French resident who works 25 days from home and spends 10 days at a client in Germany has 35 days outside Luxembourg and has lost the tolerance for the year, even though only 25 of those days were in France.
Third-country days raise a second question. The third country may have its own right to tax the salary for the days worked there under its treaty with the country of residence, whatever the 34-day count says. For short missions this rarely leads to tax in practice, because most treaties exempt short stays paid by a foreign employer, but it has to be checked for longer or repeated assignments.
Law and practice: Tax treaty France–Luxembourg of 20 March 2018, Article 14, as amended on 7 November 2022, with the amicable agreement of 16 July 2020; treaty Belgium–Luxembourg of 17 September 1970, Article 15, as amended on 31 August 2021, with the amicable agreement of 16 March 2015; treaty Germany–Luxembourg of 23 April 2012, Article 14(1a), as amended by the protocol of 6 July 2023, in force since 29 December 2023 and applicable from 1 January 2024. Luxembourg circular L.G.-Conv. D.I. No. 71 of 18 March 2024 on the German rules.
What counts as a day outside Luxembourg
The day count is where most disputes start. The rules are close but not identical, and the tax authorities of the residence country apply their own reading.
| Situation | France | Belgium | Germany |
|---|---|---|---|
| Part of a day worked outside Luxembourg | Full day | Full day | Full day if at least 30 minutes |
| Day of training or mission in a third country | Counts | Counts | Counts |
| Holidays, sick leave, weekends without work | Do not count | Do not count | Do not count |
| On-call duty performed from home | Counts if worked | Counts if worked | Counts, even without an intervention |
| Part-time or part-year work | Threshold reduced pro rata | No pro rata under the treaty commentary; Belgian practice differs | No pro rata |
A few practical points follow from the table. Answering emails for an hour at home on a Saturday is a day worked outside Luxembourg for a French or Belgian resident. A train journey on which you work counts in the country where you are when you work. A night shift that runs from 22:00 to 06:00 counts as one day under the German rules.
Claire lives in Thionville and works 80% for a Luxembourg insurer from 1 January. Her tolerance is 80% of 34 days, about 27 days. She works one day a fortnight at home, 23 days in the year, and attends a four-day training course in Brussels. Her total is 27 days: she is exactly at the limit, and one more day at home in December would move her French days into French tax.
Keep evidence. The residence country's tax office can ask for proof of where you worked, and a record kept by the employer, with dates and places, is far stronger than a reconstruction from memory at the end of the year.
Law and practice: ACD circular L.G.-Conv. D.I. No. 71 (Germany: 30-minute rule, on-call days, no pro rata); Franco-Luxembourg amicable agreement of 16 July 2020 and French administrative guidance (pro rata for part-time and part-year); Belgium–Luxembourg amicable agreement of 16 March 2015 and its commentary.
What happens when you exceed 34 days
Once the count passes 34, the tolerance is lost for the whole year, not just for the extra days. The ordinary treaty rule applies again: the salary for every day worked in the country of residence is taxable there, and the salary for days worked in Luxembourg stays taxable in Luxembourg. The split is made on the actual working days or hours.
- Taxation in the residence state. France, Belgium or Germany taxes the share of salary for the days worked there. Luxembourg exempts that share. You are not taxed twice, but the residence country also takes the Luxembourg salary into account to set the rate, so the effect on your total bill depends on your household.
- Two tax returns. You file in Luxembourg for the Luxembourg part and in your residence country for the foreign part. Luxembourg withholding does not adjust by itself; the employer can reduce it only on the basis of a certificate or a day count.
- Withholding in the other country. In Belgium and Germany the employer may need to register and withhold wage tax on the foreign share, unless the authorities accept another arrangement. In France the tax on that share is usually collected from the employee through instalments set by the French tax office.
- Permanent establishment risk. A home office used regularly can, in some cases, be a fixed place of business of the employer in the other country. Under the OECD commentary updated in 2025, a home office used for less than 50% of working time over twelve months generally does not create one. Above that, the question is whether there is a commercial reason for the work to be done there, such as serving local customers.
Marc lives in Arlon, earns EUR 120,000 a year and works 60 days from home. With about 220 working days, 60/220, or 27%, of his salary, about EUR 32,700, becomes taxable in Belgium, and Luxembourg exempts it. He files a Belgian return for that part and a Luxembourg return for the rest. His employer reduces Luxembourg withholding on the Belgian share and checks whether Belgian withholding is required.
For many households the bill changes little, because Belgian, French and German taxes on employment income are not lower than Luxembourg's. The real cost is compliance: two returns, two sets of payslip adjustments and an annual reconciliation.
Law and practice: Articles 14 or 15 of the three treaties (employment income) and the methods article of each treaty for the elimination of double taxation; OECD Model Tax Convention, Commentary on Article 5, as updated in 2025, on home offices.
What differs for French, Belgian and German residents
France. French residents declare their Luxembourg salary in France and receive a tax credit equal to the French tax on it, so it is effectively exempt but raises the rate on other French income. If the 34-day tolerance is lost, the French share is taxed in France for real. The threshold is reduced for part-time work and for a partial year. French residents insured in Luxembourg do not pay CSG and CRDS on their Luxembourg salary.
Belgium. Belgian residents are taxed in Luxembourg as non-residents, by default in class 1 even if married. They can ask to be treated as residents, and to use class 2, if more than 50% of the household's professional income is taxable in Luxembourg. That threshold is lower than the 90% test that applies to French and German residents, because the Belgium–Luxembourg treaty contains a specific rule. Belgium exempts the Luxembourg salary with progression; Belgian politicians have argued for 48 days instead of 34 for years, without result.
Sophie lives in Bastogne and earns EUR 70,000 in Luxembourg. Her husband earns EUR 40,000 in Belgium. 64% of household professional income is taxable in Luxembourg, so she can ask for assimilation and be taxed in class 2 on her Luxembourg salary, at the rate that the household's total income would bear. On these figures that lowers her Luxembourg tax compared with class 1. She makes the request in her Luxembourg tax return.
Germany. German residents are taxed in Luxembourg on their Luxembourg days and Germany exempts that income with progression. Since 2024 the treaty contains the 34-day rule in its text, together with the 30-minute rule and no pro rata for part-time work. A German resident who loses the tolerance files a German return with the German share of salary and claims the exemption for the rest.
Jonas lives in Trier and works full-time for a Luxembourg manufacturer. He works 30 days from home and spends 8 days at a supplier in Italy. His count is 38 days, four above the limit. Germany, as his state of residence, taxes the salary for the 30 home days and the 8 Italian days; Luxembourg taxes the rest. Italy is unlikely to claim the 8 days because the stay is short and the employer is not Italian. If he had spent only 4 days in Italy, Luxembourg would have taxed everything.
Law and practice: LIR Article 157ter and Article 24(4a) of the Belgium–Luxembourg treaty (assimilation of Belgian residents at 50%); ACD guidance on the assimilation of non-residents (90% test, EUR 13,000 test, 50-day rule for salaries taxable abroad); French Tax Code and the Franco-Luxembourg treaty on the tax credit method.
What a Luxembourg employer should set up, and 2026 news
For an employer, the risk is concentrated in a few employees: managers who travel, people who negotiate extra home days and those who stay at home in December to use up leave and then work a day. A written policy and a simple record solve most of it.
- Write a telework policySet a maximum number of home days per country of residence, with a buffer below 34, and say that third-country missions count.
- Record every dayUse the time system or an expense tool to capture the place of work each day. Ask employees to confirm it monthly.
- Check the social security shareCalculate the share of working time at home each quarter. Between 25% and 49%, file the framework agreement request and keep the A1.
- Plan for exceptionsFor employees who will exceed 34 days, agree the tax split in advance, adjust withholding and, where needed, register for payroll in the other country.
- Review the permanent establishment positionFor senior staff working mostly from home and dealing with local customers, document why the home office is not a place of business of the company.
- Issue annual statementsGive each employee a statement of days worked in Luxembourg, at home and in third countries for their tax returns.
2026 news. The figures have not moved. At the intergovernmental conference between France and Luxembourg in December 2025, Luxembourg proposed about one telework day a week, around 45 days a year; France asked for about two days a week, around 90 days, and compensation for its lost tax revenue. In an interview published in October 2026, the French ambassador described 45 days as possibly a step, but the financial terms remain open. On the social security side, the framework agreement continues and gained Estonia as a new member in February 2026. Employers should plan on 34 days and 49% for the rest of 2026 and for 2027 unless a signed amendment says otherwise.
Law and practice: Paperjam, interview with the French ambassador to Luxembourg, 16 October 2026; Belgian Federal Public Service Social Security, list of signatories to the framework agreement; OECD Model Tax Convention, 2025 update.
Check your telework days
Enter your situation. The checker counts home and third-country days against the tolerance for your country and reads your telework share against the social security thresholds. It assumes about 220 working days for a full-time year.
Cross-border telework check, 2026
Choose where you live and enter your days. You see whether Luxembourg keeps the right to tax your whole salary, which social security applies and what your employer has to do.
For tax, home and third-country days together.
Social security: normal rule, then the framework agreement.
A partial day is a full day in France and Belgium.
Policy, records, A1 and payroll abroad if needed.
Cross-border workers and telework: frequent questions
How many days can a cross-border worker telework from home in 2026?
For tax, 34 days a year for residents of France, Belgium and Germany who work for a Luxembourg employer. Days in the home country and in third countries count together. For social security, telework of up to 49% of working time keeps you in the Luxembourg system if your employer and you apply under the EU framework agreement.
Does a half day at home count as a full day?
Yes, for France and Belgium any part of a day worked outside Luxembourg counts as a full day. Under the German treaty a day counts if you work at least 30 minutes outside Luxembourg. Holidays, sick days and weekends without work do not count.
What happens if I exceed 34 days?
The tolerance is lost for the year. Your country of residence taxes the salary for all days worked there, from the first day, and Luxembourg taxes the rest. You file in both countries, and your employer must split the withholding. You are not taxed twice: each country taxes only its share.
Is the 34-day limit reduced for part-time workers?
For French residents, yes: the French–Luxembourg practice reduces the threshold in proportion to working time and the months worked. For German residents, no. For Belgian residents the treaty commentary says no pro rata, but the Belgian tax administration has taken a different view, so a cautious count is advisable.
Will the 34 days be raised?
Not yet. At the intergovernmental conference in December 2025 Luxembourg offered about one day a week, roughly 45 days, and France asked for about two days a week, around 90 days, with financial compensation. As of October 2026 there is no agreement with France, Belgium or Germany.
What is the 25% rule for social security?
Under EU Regulation 883/2004, someone who works 25% or more of their time in their country of residence and also works in another state is insured in the country of residence. The framework agreement on cross-border telework lets the employer and employee keep Luxembourg social security for telework below 50%, if they apply for an A1 certificate.
Can my home office create a permanent establishment for my employer?
It can in principle. Under the OECD commentary updated in 2025, a home office used for less than 50% of working time over twelve months generally is not a permanent establishment. Above that, it depends on whether there is a commercial reason for the work to be done in that country, such as meeting local customers.
The 25% rule and the framework agreement on telework
Social security follows EU law, not the tax treaties. Regulation 883/2004 makes an employee subject to the legislation of one country only. A cross-border worker who works only in Luxembourg is insured there. Someone who habitually works in two or more states is insured in their country of residence if they do a substantial part of their work there, defined as 25% or more of working time or pay.
Telework at home counts as work in the country of residence. Without any special arrangement, a French resident who works two days a week from home (40%) would therefore be insured in France, and the Luxembourg employer would have to register with the French social security system and pay French contributions, which are far higher.
The framework agreement on habitual cross-border telework fixes that. Since 1 July 2023, employers and employees can ask for the employee to stay under the social security of the employer's state if telework in the country of residence is less than 50% of total working time. France, Belgium, Germany and Luxembourg all signed from the start. 23 states take part, including the Netherlands, Austria, Spain and Switzerland; Estonia joined on 1 February 2026.
The framework agreement has conditions. It covers telework only, from the home country, using the employer's IT systems. It does not cover employees who also work in their home country in another way, such as visiting customers, people with several employers, or people who also work in a third state on a regular basis. The employer and employee must both agree, and the request can be backdated by no more than three months.
Law and practice: Regulation (EC) No 883/2004, Articles 11 to 16; Regulation (EC) No 987/2009, Article 14(8) on substantial activity; Framework agreement on the application of Article 16(1) of Regulation 883/2004 in cases of habitual cross-border telework, in force since 1 July 2023, list of signatories kept by Belgium as depositary; CCSS guidance on applications.