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

Tax filing depends on whether the couple is married or in a registered partnership (PACS), and on the tax residency status of the EU institution employee.

For married couples:

Married couples file a joint tax return by default in Luxembourg. The EU institution employee’s income is exempt from Luxembourg taxation and does not need to be declared as taxable income. A certificate of employment from the EU institution must be provided. The couple can claim joint deductions such as mortgage interest or insurance premiums.

For PACS couples:

PACS couples may only file a joint tax return if both partners are Luxembourg tax residents — this is a legal condition for joint taxation of PACS partners. If filing jointly, the EU institution employee must submit a certificate of employment that explicitly indicates their Luxembourg tax residency. If the EU institution employee is not a Luxembourg tax resident, only the Luxembourg-employed partner declares their salary and claims deductions individually.

Disclaimer: Tax residency is a legal status for taxation purposes and does not necessarily correspond to where the person physically lives. For example, an EU institution employee might live in Luxembourg but have their tax residency in another country. Because of this distinction, the eligibility for joint taxation for PACS couples depends strictly on the tax residency status, not on physical residence.

Updated on: 27/06/2025

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