The appointment at the population office lasts twenty minutes and decides the pace of your first three months. It is the moment Luxembourg formally acknowledges that you live here, and almost every other formality waits behind it.
Who has to do it, and when
Anyone establishing their usual residence in a Luxembourg commune must declare it to the population office of that commune. Nationality does not exempt anyone, it only changes the deadline and the supporting documents.
Citizens of the EU, the EEA and Switzerland have eight days from establishing residence. Third-country nationals have a shorter window, commonly stated as three working days by the City of Luxembourg. If you move house within Luxembourg later, the same obligation applies again, at the commune you are moving into.
Because Luxembourg communes enjoy a degree of autonomy in how they run this procedure, details differ. Some accept appointments online, some operate on walk-in hours, some ask for a document another commune waves through. The rule that holds everywhere: contact the specific commune before you go, and ask them for their own list.
What to take
A valid passport or national identity card, for every member of the household, children included. Proof that you occupy the address: a signed lease is the standard document, a deed of sale if you have bought, and in the absence of either, a written authorisation from the owner or occupant of the property, or an attestation from a serviced residence.
For third-country nationals, the visa, residence permit or residence card, as applicable. For families, a family record book or the equivalent civil status documents, which is where marriage and birth certificates are checked.
Anything not issued in French, German or English needs a certified translation by a sworn translator. This is the single most common reason an appointment fails, and it is entirely avoidable. Arrange translations in your country of departure, where they are usually cheaper and faster, and bring originals as well as translations.
What you leave with
You leave with a certificate confirming the declaration. Keep it accessible and take a photograph of it. Until your social security card arrives in the post, this piece of paper is the document your employer, your bank and any administration will ask to see as proof that you are registered here.
The substantive output is the national identification number, the thirteen-digit matricule, drawn from the national register of natural persons. It is not a formality. It identifies you to the tax administration, to social security, to schools, to the health system and to a good many private institutions. You will type it more often than your own telephone number.
The second step EU citizens forget
The declaration of arrival is not the whole procedure for EU nationals staying more than three months. Within three months of arriving, you also complete a registration certificate at the same commune, with documents corresponding to your category: an employment contract or a signed commitment to hire for employees, evidence of activity for the self-employed, proof of sufficient resources and sickness cover for non-working residents, enrolment documents for students, and family relationship documents for accompanying family members.
It is easy to skip, because nothing visibly breaks when you do. The consequence appears years later, when a permanent residence application or a naturalisation file requires an unbroken record of lawful residence and there is a gap where the certificate should be. Doing it in month two costs an hour. Reconstructing it in year six costs considerably more.
Non-EU arrivals: a different track running in parallel
Third-country nationals normally arrive with an authorisation to stay obtained before travelling, then complete the arrival declaration at the commune and, within the applicable period, undergo the medical check and apply to the Immigration Directorate for the residence permit itself. The commune step does not replace the immigration step; it feeds it. Registering promptly matters here more than for EU nationals, because the immigration file relies on the communal record.
Family members of EU citizens who are themselves third-country nationals follow yet another variant, with a residence card rather than a registration certificate. If your household mixes nationalities, ask the commune to walk you through each person separately rather than assuming one procedure covers the family.
Addresses, and why the wrong one is expensive
The address on the register is not decorative. It determines your competent tax office, your commune of residence for school allocation, your waste and water contracts, your electoral rights in communal elections after the qualifying period, and the amount of communal tax on the property you occupy.
Registering at an address where you do not live, even helpfully, at a colleague's flat while you continue to look, creates a mismatch that surfaces at the worst moments: a delivery of official post you never receive, a school allocation in the wrong commune, an immigration file that does not reconcile. If your address is genuinely temporary, tell the population office that and ask how they want it recorded.
Practical notes that save an appointment
Go early in the week and early in the day; population offices in the capital are busiest at the start of the month and around the September and January arrival peaks. Bring more than you think you need, particularly civil status documents, because a document you brought and did not use costs nothing while a document you left at home costs a second appointment.
Register your household together where possible. Bring bank details if the commune collects them for waste and water. And ask, while you are there, about the practical municipal matters nobody tells arrivals: which bins are collected on which day, where the recycling centre is, whether a resident parking permit is available for your street and how long the waiting list runs.
When you leave
The obligation is symmetrical. Anyone leaving Luxembourg to settle abroad must declare their departure to the commune of their last residence, before departing. Skipping it leaves you administratively resident in a country you no longer live in, with consequences for tax residence and for the tidiness of any future return. It takes one visit.
If you are moving inside the country instead, declare at the new commune and the record transfers. That is also the natural moment to reconsider the address itself, and our district guides exist to make that comparison faster than a second year of guessing.
A stronger reading of what you leave with starts by asking what would change for the resident on an ordinary weekday.
Editorial note: Procedures at communal level vary from one commune to another and change over time, and the requirements differ by nationality and personal situation. Verify the current requirements with the commune where you will live, or on Guichet.lu, before your appointment.
Questions worth carrying into real life
For the declaration of arrival: what to bring to the commune and what you leave with, the final test is whether the advice survives contact with an ordinary week. Think about the practical sequence that makes settling into Luxembourg easier.