ALEBA’s Success: A significant improvement for cross-border workers regarding Luxembourg tax declaration

This clarification is a tangible success resulting from ALEBA’s commitment. We identified this harmful administrative practice, challenged it with the Luxembourg Direct Tax Administration (ACD) on behalf of the affected cross-border workers, and demanded a clear ruling. The ACD’s response demonstrates just how important it is to be able to rely on a strong union capable of addressing everyday problems and defending the interests of its members and employees before the relevant authorities.

In its ruling of April 16, 2026, the Luxembourg Administrative Court ruled that a box on Form 100 that was inadvertently left unchecked should no longer automatically result in the rejection of tax equivalence under Article 157ter of the Income Tax Law (L.I.R.). The ACD confirmed to ALEBA that it would take this case law into account in its administrative practices going forward.

A set of consistent information included in the tax return may now be considered a request for tax treatment under Article 157ter. This includes, in particular, information regarding special expenses, foreign income, personal and family circumstances, as well as the spouse’s signature. In case of doubt, the ACD must, in principle, clarify the facts before issuing the annual tax assessment and, if necessary, request further details.

This represents a significant simplification and better protects cross-border workers from the consequences of a simple clerical error. Nevertheless, we recommend that all cross-border workers continue to explicitly check the corresponding box on Form 100 and review their annual tax statement as soon as they receive it.

If the tax treatment has not been applied despite the information provided, the taxpayer must take action within the applicable appeal period and, if necessary, seek tax advice. Once the annual tax statement has been issued, it is no longer possible to submit a new request for tax treatment. However, it is possible to argue that the request existed from the outset based on the information already provided.

Taxation can be complex—fortunately, ALEBA understands it clearly and helps you check the right box. This process perfectly illustrates the concrete added value that ALEBA’s advocacy for individual interests can bring to all employees, and in particular to cross-border workers.