How do you declare tax when one partner works for an EU institution and the other in Luxembourg?

The possibility of filing a joint tax return in Luxembourg depends on the type of union (marriage or PACS), but above all on the tax residence of the partner employed by a European institution.

In other words: marriage or PACS alone is not sufficient; it is first necessary to determine where the partner is a tax resident.

The salary of European Union officials and staff is exempt from tax in the country where they are posted. However, their other income (e.g., rental income, investment income) may be taxable depending on their tax situation (resident or non-resident).

Married couples

A married couple can only be taxed jointly in Luxembourg if both spouses are considered Luxembourg tax residents.

In this case, the salary of the EU employee is exempt from Luxembourg tax (based on a certificate from the institution), and the couple can benefit from joint deductions (e.g., mortgage interest, insurance, etc.).

If the European employee is not a Luxembourg tax resident, then joint filing is not possible: the spouse taxed in Luxembourg files alone.

PACS partners

For PACS partners, the logic is the same:

Joint filing is only allowed if both partners are Luxembourg tax residents.

If the EU institution employee is not considered a Luxembourg tax resident, PACS does not entitle the couple to file jointly; only the partner taxed in Luxembourg files an individual return.

How to determine the tax residence of the European official?

1. The partner came to Luxembourg solely to take up a position in a European institution:

In this case, the tax residence remains in the country of origin, even if the couple lives in Luxembourg.

No joint taxation, whether in marriage or PACS.

2. The partner already lived in Luxembourg or arrived for a reason other than joining a European institution:

Here, the tax residence is considered Luxembourgish.

Joint taxation is possible (for marriage in the usual way, and for PACS provided the PACS existed throughout the year and the partners lived together in Luxembourg).

Can joint taxation be requested if one spouse is non-resident?

Yes, upon request, under conditions (Article 3, lettre d) L.I.R.):

The couple can be taxed jointly if:

• the resident spouse earns at least 90% of the household’s professional income in Luxembourg, or
• the household’s net taxable income abroad is < 13.000€.

In this case, both spouses are taxed as residents, and all worldwide income is taken into account.

Updated on: 07/11/2025