How Luxembourg and France Count the 34-Day Teleworking Limit

A French resident employed in Luxembourg can work up to 34 days a year outside Luxembourg — from home, at a client's premises, or in a third country — before France takes the right to tax that part of the salary. A circular issued by Luxembourg's tax administration on 24 June 2026 sets out how those days are counted, and the method is stricter than most people assume: any fraction of a day worked in France counts as a whole day, and crossing the threshold moves every one of those days into French taxation, not only the ones above 34.

The tolerance itself sits in point 3 of the protocol to the Luxembourg–France double taxation convention of 20 March 2018, as amended by the avenant of 7 November 2022. The practical method comes from a mutual agreement between the two administrations signed on 16 July 2020, and the threshold has stood at 34 days since the 2023 tax year. Circular L.G. – Conv. D.I. n. 61 of 24 June 2026 is the current reference. It replaces the circular of 21 October 2020, which predated the 2022 amendment, so older summaries built on that version no longer describe the current position. The new text runs to eleven pages in French and is published as a photocopier scan rather than as searchable type.

What counts as one of the 34 days

The test is physical presence: the employment is treated as exercised wherever the employee physically is while doing the work that earns the salary. On that basis the circular sets a deliberately blunt counting rule, translated here from the French.

Any day or fraction of a day on which the employee is physically present in their State of residence and/or in a third State to exercise their employment, and any day or fraction of a day on which the employee attends professional training in their State of residence and/or in a third State, is counted as a whole day for the purposes of the 34 days.

Two consequences follow. A morning spent answering email at home in Thionville before driving to the office after lunch consumes a full day of the allowance, not half of one. And training days abroad count, even though the employee is not working for the employer that day.

The circular works the arithmetic through. An employee with 220 working days in a year spends 181 in Luxembourg, 25 in France, 6 on training in a third country, and 8 days working the morning in France and the afternoon in Luxembourg. The count is 25 + 8 + 6 = 39 days, and the threshold is breached.

What follows is where the rule bites. Exceeding 34 days does not cost the employee only the excess; it removes the tolerance altogether and the ordinary treaty rule returns. France then taxes the salary relating to all the days worked on its territory and in third countries — 39 days in that example, not the five by which the limit was passed. Days worked in a third country are taxable in France too, unless a treaty between France and that country assigns them elsewhere.

One refinement is easy to miss. Split days count as whole days for the threshold test, but only as halves when the taxable share is worked out afterwards. The eight mornings in the example each consume a full day of the 34, yet only four days' worth of salary (8 × 50%) follows France, because the afternoons worked in Luxembourg remain Luxembourg's. The two calculations are not the same one, and treating them as identical gets the answer wrong twice over.

The days that do not count

Days spent in France for reasons other than working fall outside the count entirely. The mutual agreement gives a non-exhaustive list:

• days of paid leave;
• weekly rest days and public holidays, but only where the employee is not obliged to work them;
• days of incapacity for work through illness;
• cases of force majeure beyond the control of both employer and employee.

A Luxembourg public holiday spent at home in France is therefore not a teleworking day. A Luxembourg public holiday the employee is rostered to work from home is one.

Part-time and mid-year contracts get a smaller allowance

The 34 days assume a full year on a full-time contract. Otherwise the threshold is cut in proportion, and rounded down. The circular gives three worked cases:

• a 75% part-time contract: 34 × 75% = 25.5, rounded to 25 days;
• a full-time contract starting on 1 July: 34 × 6/12 = 17 days;
• a 75% contract starting on 1 October: (34 × 75%) × 3/12 = 6.4, rounded to 6 days.

The resulting figure is a ceiling for the calendar year, and it holds for the year as a whole even where the employee has worked under several separate contracts.

Social security runs on a different clock

The most common error is to assume a single number governs both tax and social security. It does not. Affiliation turns on a percentage of working time, not on a count of days.

Under the European framework agreement on cross-border telework, an employee who teleworks between 25% and less than 50% of total working time can stay affiliated to Luxembourg social security. The figure is a monthly average, and its definition of working time is not the tax one: sick days count as working time, while paid holidays do not. Telework below 25%, or at 50% and above, falls outside the agreement and is handled as multistate work under the European social security regulation.

The relief is not automatic. The employer must declare the telework to the Centre commun de la sécurité sociale, electronically through SECUline or on the paper pluriactivity form, and an A1 certificate is then issued for up to three years. Since 1 July 2024 a declaration can be backdated by only three months, so late filing leaves a gap that cannot be repaired afterwards.

Proof, finally, is the employee's responsibility rather than the employer's. The circular expects the taxpayer to evidence physical presence: the employment contract or an employer attestation naming the duties and where they are performed, timesheets, named transport tickets, hotel and car-hire invoices, signed attendance lists from meetings and training, canteen or card receipts from the country of activity, and mission orders. Keeping that record as the year goes along is considerably easier than reconstructing it two years later under assessment.