Luxembourg Cross-Border Worker Tax-Day Tolerance Calculator

What is the 34-day tolerance for Luxembourg cross-border workers?

Under each of Luxembourg's double-tax agreements with its neighbours, the starting rule is the same: salary for a day worked outside Luxembourg is taxable where you live, not where the employer is. The tolerance is a carve-out from that rule. If the total number of days you were physically present in your own country, or in some third country, in order to work stays at or below the threshold, the whole year is treated as if you had exercised the job in Luxembourg, and the whole salary stays taxable in Luxembourg through withholding tax. The threshold is 34 days per year for residents of France, Belgium and Germany. It is one number in 2026, but it arrived by three different routes and it is counted in three different ways, which is where most people get it wrong.

The Luxembourg tax administration (Administration des contributions directes) publishes the treaty table that fixes each of these dates and the circulars that explain how the days are counted. The Luxembourg government portal states the combined position plainly: the bilateral agreements "set tolerance thresholds (currently 34 days per year)", and a cross-border worker who stays below the threshold keeps their salary taxed in Luxembourg, while one who exceeds it is taxed in the country of residence on the share of income relating to the days worked outside Luxembourg. What the portal summary does not spell out is that the arithmetic behind the threshold is not identical in the three agreements, and the calculator above applies each country's own arithmetic.

Where the number comes from: three agreements, three dates

The 34 days are not a Luxembourg domestic rule that the treaties then adopt. They sit inside each treaty, or in a protocol or mutual agreement attached to it, and each one has its own effective date. That matters if you are checking an older year, because the same cross-border worker who is comfortably inside the tolerance for 2026 may have been over it under the threshold that applied in 2021.

Two of those dates carry a trap. The Belgian avenant applies from 1 January 2022, but the transition year was not a full 34 days: the published guidance grants the 34 days for 2022 only for the period from 1 July to 31 December 2022. And the German rule is drafted as a negative: article 14(1a) keeps the salary taxable in Luxembourg where the work is carried out in the residence state or a third state on fewer than 35 working days in the calendar year. Thirty-four days is inside; the thirty-fifth day is the trigger. The Luxembourg circular of 18 March 2024 explains both the increase and the counting rules that go with it.

How each country counts a day against the threshold

France: any fraction counts, but the threshold shrinks with your hours

The French side is governed by an accord amiable on the application of point 3 of the protocol, published by the French tax administration. The text still refers to 29 days because it was signed on 16 July 2020, and the note at the top of the published version states that the modalities are identical and that the 29-day figure must be read as 34 days. The counting rules are the part that matters. Days on which you are physically present in France, or in a third state, in order to exercise your employment are counted. Any fraction of a day counts as a whole day, so a morning at home and an afternoon in Luxembourg is one day, not half. Days spent in France on professional training count. Days of leave, weekly rest, public holidays when you are not required to work, sick leave and force majeure do not count, because your presence at home on those days is not explained by the job.

France is also the only one of the three where the threshold itself moves. The accord states that for part-time work, or for work during only part of the year, the threshold is reduced proportionally according to the contractual working time and the duration of the contract, and that where the proportion does not come to a whole number of days the lower whole number is used. A three-day-a-week contract for the full year therefore does not get 34 days, and neither does a full-time contract that ran for six months. The threshold is assessed annually and globally, including where you held several separate contracts in the same year, and overtime pay is taxed where the overtime was actually worked.

Belgium: any fraction counts, and the threshold never shrinks

The Belgian guidance published by the Luxembourg tax administration is short and unusually explicit on three points. First, the days to count are the days on which the employee is physically present in Belgium, or in a third state, in order to exercise the employment. Second, any fraction of a day counts as a whole day, so partial days at home are fully counted against the 34. Third, and this is the contrast with France, the threshold is not reduced proportionally either for a part-time contract or for work during only part of the year. A Belgian resident on a half-time contract gets the same 34 days as a full-time colleague. The same guidance sets an outer limit on the whole mechanism: the frontier-worker paragraph applies where the salaried activity is exercised partly outside Luxembourg for a period not exceeding 341 days in the tax year, and beyond that the ordinary rules of article 15 take over.

Germany: 30 minutes, and only paid working days

The German agreement counts differently again. The protocol of 6 July 2023 introduced article 14(1a), and the Konsultationsvereinbarung agreed by the two competent authorities on 11 January 2024 fills in the detail, with the Luxembourg circular of 18 March 2024 explaining how the administration reads it. The threshold is not prorated for a contract that starts or ends during the year, nor for part-time work: the circular gives worked examples of a 75% contract, a contract starting on 1 July and a 75% contract starting on 1 October, and in each case the full 34 days is available. A day with shortened hours is a full working day for the count. The distinctive rule is the 30-minute tolerance: activity is treated as exercised in Germany or a third state only if it lasted at least 30 minutes, so answering work emails at home before driving to Luxembourg does not consume a day. Only effective working days for which remuneration is received are counted, which means days without any activity, such as holidays or bad-weather days, drop out. Paid on-call duty from home does count, even where you were never called out, and a rotating shift that starts on one calendar day and ends on the next counts as a single day.

Worked examples: at the limit, one day over, and the part-time case

The examples below use the same inputs as the calculator and can be reproduced in it. They are there to show how much the answer changes when the country changes, because the same set of facts does not produce the same result in Paris, in Arlon and in Trier.

What happens when you exceed the tolerance

The single most expensive misunderstanding about this rule is that only the excess is taxed. That is not how any of the three agreements works. Once the tolerance is exceeded, you lose the benefit of the provision for the whole year, and the country where you live recovers the right to tax the remuneration for the days you were physically present there, or in a third state, in order to work. The French accord amiable says it in one sentence: the residence state recovers its right to tax "à compter du premier jour". The Belgian guidance uses the same formula, and the German circular simply says that where the 34-day threshold is exceeded, only the general rules of article 14(1) and (2) apply again.

What that means in practice is a reallocation, not a penalty. Luxembourg keeps taxing the salary attributable to the days you actually worked in Luxembourg. Your country of residence taxes the portion attributable to the days you worked at home or elsewhere, and then relieves the double taxation under the treaty, which in France takes the form of a credit against French tax. The cost of getting it wrong is therefore not a fine but a second tax bill with a credit attached, plus interest and rework if the position is corrected years later. Because the counting rules differ, the same calendar can be inside the Belgian threshold and over the French one in the same month.

Who qualifies as a frontier worker in the first place

Before any of this matters, you have to be within the personal scope of the treaty rule. The agreements apply to a resident of one state who exercises an employment in the other state and who is physically present in the residence state or a third state for a limited number of days while doing so. Nationality is irrelevant for the tax rule; residence is what counts. You are not eligible for the tolerance if you are not tax resident in France, Belgium or Germany under that country's own domestic rules, if your work outside Luxembourg is not employment income at all, or if you work for an employer that is not Luxembourg-resident and the treaty's other conditions are not met. Company directors, partners and self-employed consultants fall outside the employment article and are not covered by the calculator. If your situation is one of those, the number above will not describe your position and you should not rely on it.

What this calculator does not decide

Four things sit outside the 34-day count, and each of them can move your final bill by more than the tolerance itself. Tax residence is the first. The tolerance allocates employment income; it does not decide where you live for tax purposes. Each country decides residence under its own domestic law and, where two states both claim you, under the tie-breaker in the treaty. Staying under 34 days does not stop France from treating you as resident, and going over 34 days does not make you resident anywhere. The second is social security, which follows a separate European framework rather than the tax agreements. The Luxembourg government portal explains that the multinational framework agreement in force since 1 July 2023 lets cross-border workers work from home for between 25% and 50% of their total working hours without changing their social security system, and that above that band the system usually switches to the country of residence. That percentage is not the 34-day test and the two can point in different directions.

The third is withholding mechanics. Your Luxembourg employer withholds Luxembourg tax on the salary it pays, and that withholding does not settle your residence-country position. The fourth is the rest of your income: rental income, a spouse's salary in the residence state, investment income and pension contributions all sit under different articles of the same treaty, and a change in your day count does not change them. This tool models the day tolerance only, because that is the part that can be calculated from a calendar without knowing your tax rate.

What to do next, in order

1. Step 1 — Reconstruct the year day by day. Start from your employer's time records and your own travel history, and mark each day as Luxembourg, residence state, or third country. Do this before you look at the threshold, because the answer depends on the calendar and not on the story.
2. Step 2 — Apply your country's counting rule. France and Belgium count any fraction of a day in full and exclude leave, rest days and sick days; Germany ignores activity under 30 minutes and counts paid on-call days. Do not mix the three rules.
3. Step 3 — Check whether your threshold is prorated. If you live in France and worked part-time or only part of the year, scale 34 days by your contractual hours and by the months you worked, then round down. If you live in Belgium or Germany, leave the 34 days alone.
4. Step 4 — Compare, and act on the margin. A handful of days of headroom in October is a warning, not a comfort: one extra week at home in December can take you over, and the consequence is a residence-country tax bill on every home day of the year.
5. Step 5 — Fix the record with your employer. Ask payroll to align the days recorded in the payroll system with the days you actually worked, and to keep the supporting documents. Under all three agreements the burden of proving physical presence falls on the taxpayer.
6. Step 6 — Get the residence-country side reviewed before you file. If you are over the threshold, take the day count and the withholding statements to an adviser in your own country. The reallocation and the credit are mechanical once the day count is right, and expensive to fix afterwards if it is wrong.

Documents to keep for the day count

The French accord amiable lists the evidence it expects, and the Belgian guidance follows the same logic: the proof has to show physical presence in the state where you say you were. A contract and an employer letter are enough only for jobs that cannot be done anywhere else, such as a shop cashier or a hospital nurse. For anyone whose work can travel, the administration expects dated records.

1. The employment contract, or an employer attestation stating the functions and the place where they are performed.
2. Nominative time sheets, clocking records or the payroll system's day-by-day export for the tax year.
3. Nominative transport documents: train tickets, flight tickets, motorway toll statements, fuel receipts for the commute.
4. Meeting and training attendance lists, mission orders, and dated client visit records for travelling roles.
5. Nominative hotel and car-hire invoices for third-country travel, and mobile phone roaming statements for the days abroad.
6. Luxembourg payslips with withholding, and the annual tax certificate, so the days and the pay can be reconciled.

What changed, and what to watch in 2026

All three thresholds have moved in the last five years, which is why older guidance on the internet is actively misleading. Germany moved from 19 to 34 days for calendar years from 2024, with the protocol signed on 6 July 2023 and the joint interpretation agreed on 11 January 2024, and it is the first time the tolerance was written into article 14 rather than left to a mutual agreement. Belgium moved from 24 to 34 days with effect from 1 January 2022, though the amending avenant only entered into force on 10 February 2023. France moved from 29 to 34 days for tax periods from 1 January 2023, with the avenant signed on 7 November 2022 and the French administration's published note confirming that the older 29-day wording is to be read as 34. Any page still quoting 19, 24 or 29 days is describing a year that has closed.

Two things are worth watching rather than assuming. The French avenant carries its own review clause: article 3 required the two states to meet before 31 December 2024 to settle the conditions applying from 1 January 2025 and, where appropriate, to conclude a new avenant, and article 4(3) keeps the instrument in force until the end of the year following its entry into force and renews it automatically if no new avenant is signed. So the 34 days is a figure with an expiry mechanism rather than a permanent settlement, and the number published by both administrations today is the number that applies. The day-counting rules are also administrative rather than legislative in Germany and France: they live in a Konsultationsvereinbarung and an accord amiable, which can be revised without a new treaty. Check the effective date of any figure before you rely on it for a year that has already been assessed, and check the current circular before you plan the next one. Our guides index and the country pages carry the surrounding context on living and working in Europe, and the full tool library has the other calculators.