Cross-border remote work: the two 2026 thresholds

Direct answer

There are two thresholds, they are independent, and confusing them is the costliest error. The tax threshold is 34 days per year for residents of Belgium, France and Germany. The social security threshold is 49.9 % of working time.

The decisive condition: beyond 34 days, it is not only the excess that becomes taxable in the country of residence. All days worked outside Luxembourg become taxable there, including the first 34.

The framework: amendments to the bilateral tax treaties. Belgium since the agreement ratified in late 2022, with effect from 1 January 2022. Germany raised from 19 to 34 days in 2024. France, the amendment of 7 November 2022 to the treaty of 20 March 2018, ratified by France in February 2025. On the social security side, the European framework agreement on cross-border teleworking, with the derogation formalised through the A1 form.

The nuance: an employee can remain affiliated to Luxembourg social security while having crossed the tax threshold. The two regimes do not speak to each other.

The count in practice

An employee working remotely two days a week across a full year reaches roughly 96 days outside Luxembourg.

On the social security side they stay below 49.9 % and keep Luxembourg affiliation, subject to A1 formalisation. On the tax side they crossed the 34-day threshold months earlier, and all their remote days become taxable in their country of residence.

This is exactly the configuration that produces the year-end adjustments we see. The employer handled social security correctly. Nobody tracked the tax side.

What the 34-day threshold counts

The threshold does not cover home working alone. It captures all days worked outside Luxembourg territory on behalf of the Luxembourg employer: remote work, business travel, training abroad, assignments.

The count is assessed annually and pro-rated for part-time or partial years. Business travel days are the ones companies most often forget. A salesperson working remotely one day a week believes they are at 48 days, already beyond the threshold, and discovers at year-end that visits to Belgian and German clients counted too.

The circular of the Director of Taxation dated 24 June 2026 clarifies the counting method for French cross-border workers under the treaty of 20 March 2018. It does not change the threshold. It clarifies the method, which removes an area of uncertainty employers had been managing cautiously. See our payroll page for the full reporting framework.

The cliff effect, and why it is abrupt

The rule deserves to be stated without softening: crossing by a single day beyond 34 moves all days worked outside Luxembourg into the taxing rights of the country of residence. There is no gradation.

For a French cross-border worker, the treaty applied since 2025 replaced the effective rate method with a tax credit, which brings Luxembourg income into the calculation of the French household's tax rate. Some households lose, others do not.

We state it honestly: crossing the threshold is not mechanically unfavourable. Depending on household composition and income level, residence-country taxation can prove neutral or even more favourable. What we advise against is crossing it without having quantified it. The decision should be taken, not suffered.

The social security threshold and the A1 form

Social security follows a different logic. A cross-border worker can work up to 49.9 % of their time from their country of residence while remaining affiliated to Luxembourg social security, provided the derogation is formalised.

That formalisation is not optional. Without an A1, affiliation can be challenged by the institution of the country of residence, with retroactive effect touching employer and employee alike.

Any structured remote work policy beyond one day a week should be accompanied by a systematic A1 review on hiring and at every change of rhythm.

Where negotiations stand

Luxembourg and France are discussing an increase in the number of days. In June 2025 France proposed an annual financial compensation in exchange. The Luxembourg Finance Minister recalled the amounts already paid towards transport infrastructure. In February 2026 both sides declared themselves favourable in principle, without agreement.

No change is announced on the Belgian or German side.

Do not build an HR policy on an expected increase. Until an amendment is signed and ratified, the enforceable threshold remains 34 days.

What we put in place

A monthly count per employee, separating remote work from business travel. An alert at 25 days, leaving time to decide before the cliff. An A1 review at every change of rhythm. And for employees who deliberately exceed it, a quantified simulation beforehand, so that crossing is a documented choice.

None of this is sophisticated. It is a matter of discipline.

This article sets out the rules as they stand at the publication date. Thresholds, treaties and agreements change, and ongoing negotiations may alter the applicable framework. Any individual decision should be simulated taking household composition into account.