When do I have to file my tax return?

Whether you are a cross-border worker or a resident, an employee, self-employed, or retired, the income you earn in Luxembourg makes you a taxpayer. But when do you have to send your tax return? Here’s a reminder of the rules on this matter.*

A reminder

First of all, please note that in certain cases, you are not required to submit an annual tax return (assessment by declaration, form 100), whether you are a resident or non-resident. No, this does not mean that you pay nothing to the State, but rather that the tax withheld at source from your income is sufficient and you consider that you have no extraordinary expenses or other deductible costs to declare in order to reduce your tax amount. Is this your situation?

Simply put, since the 2018 tax year, only taxpayers classified in category 1 and 1A (residents and non-residents) who receive only one type of income subject to withholding tax and whose taxable income is less than €100,000 are exempt from filing a tax return. As Article 157bis has been amended, non-resident taxpayers classified in category 2 must submit a tax return in Luxembourg to maintain tax class 2, otherwise they will be reclassified to class 1. For more details, consult the website of the Direct Tax Administration (ACD).

For all other taxpayers, the question is not so much whether you need to file a return, but rather when? The basic principle is that you always declare the income of the previous year. This year, therefore, you declare last year’s income, while your income for the current year will be declared next year.

In practice

Every year, in principle at the beginning of the 2nd quarter of the current year, you will receive either:

• • an invitation to download and complete the declaration forms on the ACD website
  • a paper form (model 100) by post
  • a simple and pre-filled declaration (only for eligible persons)

The deadlines for submitting tax returns have changed since the 2022 tax year. Resident and non-resident taxpayers now have until December 31 at the latest to complete and submit their declaration. You must therefore submit your 2025 declaration for 2024 income before December 31, 2025.

To submit your completed and signed tax return, you have three options:

• • by post, sending it to the competent tax office
  • electronically in PDF format via MyGuichet.lu
  • via the electronic assistant on MyGuichet.lu (if you meet the eligibility requirements)

Attention: If you send your form by mail, do not wait until the last minute. It is the date of receipt of the form by the ACD that is taken into account.

More information about the electronic assistant and simplified declarations can be found on the ACD website.

Do not try to save time without reason. As the ACD mentions on its website, the deadline for submitting the income tax return must be respected, otherwise a late filing or non-filing penalty, a financial fine, or even both sanctions may apply. In case of late submission, be aware that, in addition to a possible penalty, the processing time for your declaration will be longer. Not ideal if you are expecting to get a refund on some of the taxes paid.

Good to know: The taxpayer who is not required to complete a tax return or who is not subject to assessment taxation has the possibility to regularize the tax withheld at source by completing an annual statement (form 163).

In a nutshell:

Attention, if you are a company director, you have other tax obligations and therefore different additional deadlines to keep in mind.

* Content translated from French by the BIL GPT AI tool