The 34-day rule: what the June 2026 circular clarifies

On 24 June 2026, Luxembourg's direct tax administration published a circular on how the 34-day tolerance threshold applies to cross-border workers. It replaces a 2020 text that had become obsolete, and it lands at the moment telework has become the norm rather than the exception.

The number itself has not changed. But the circular settles several questions cross-border workers had been asking for years — and most of the answers point towards the strictest possible count.

What the circular changes — and what it does not

The circular creates no new right. The 34-day threshold comes from the tax treaties and their amendments: on the French side, the amendment in force since 1 January 2023; on the Belgian side, the protocol that raised the tolerance from 24 to 34 days with effect from 1 January 2022. What the circular does is state how the Luxembourg administration reads that threshold in practice.

In other words: it does not give you extra days. It removes the grey areas many cross-border workers had settled into — "half a day only counts as half", "training isn't telework", "I'll reconstruct it if anyone asks".

The threshold stayed at 34. It is the definition of a "day" that just got tighter.

The test: physical presence

The circular applies a single, deliberately simple test: where were you physically located while working? Neither the nature of the task, nor the employer's location, nor whether you were "reachable" changes the answer.

That choice has one direct and widely underestimated consequence: any fraction of a day worked outside Luxembourg counts as a full day. Two hours of telework from home in the morning, then the drive to the office in Luxembourg City for the afternoon — the counter still moves by one whole day.

What uses up a day, and what does not

The table below summarises the reading applied. It states the general principle; a specific situation can always require its own analysis.

Training and business trips: the clarification that surprises

This is the point most often discovered too late. A two-day seminar in Paris, an industry conference in Antwerp, a trip to a Dutch client: under a physical-presence test, none of these are "days in Luxembourg". They consume quota exactly like telework does.

For a salesperson or a travelling consultant, the threshold can therefore be reached without a single telework day. That is why a log that does not distinguish day types eventually lies: the trip has to be recorded alongside telework, even though the employee does not experience it as "working from home".

Proration: your ceiling may not be 34

The circular confirms that the threshold is reduced proportionally for part-time contracts and incomplete years. An employee at 75% hired on 1 October does not get 34 days but only a handful — the cited example lands on 6 days.

The full calculation — part-time, mid-year start, early leaver — is covered in a dedicated article: working out your personal prorated threshold.

The burden of proof sits with you

This is probably the paragraph with the heaviest consequences. It is not for the administration to show that you went over: it is for you to show where you were. The evidence listed as acceptable is concrete and verifiable:

• Employment contract and any telework addendum.
• Timesheets or the employer's clocking system.
• Travel documents — tickets, expense claims.
• Hotel invoices for assignments with an overnight stay.
• Attendance lists for meetings or training sessions.

A spreadsheet reconstructed the following spring, from memory and an incomplete Outlook calendar, is not proof. A log kept day by day, timestamped, exportable and consistent with the other documents is a far better one.

What about Belgian cross-border workers?

The 24 June 2026 circular was written in the context of the France–Luxembourg treaty, but it expresses how the Luxembourg administration reads the tolerance threshold in general. Belgian cross-border workers are subject to an identical threshold — 34 days — under the protocol ratified on 22 December 2022, with retroactive effect from 1 January 2022.

Two nuances are worth keeping in mind:

• Each bilateral treaty is a separate text; the Belgian and Luxembourg administrations may differ on a point of detail.
• The Belgium–Luxembourg treaty does not cover every status the same way — public-sector staff, in particular, follow their own rules.

The practical consequence is identical on both sides of the border: precise counting has become a matter of documentation, not intuition.

Frequently asked questions

This article sets out the general framework applicable to cross-border workers. It is not tax advice and does not replace an analysis of your situation by your employer, your adviser or the competent authority. Rules change: check the update date above.