March 22, 2023

Completing your Luxembourg tax return: hints and tips

Most Luxembourg citizens and cross-border workers must complete a tax declaration in Luxembourg every year. The declaration gives you the opportunity to deduct various expenses and so  reduce the amount of tax.

Although Luxembourg has the reputation of being less complicated than its neighbours, there are always some queries. In this article, we’ll take a look at the main rules to follow.

man working on calculator and computer to prepare his tax return

Luxembourg tax return: dates and timescales

In Luxembourg, you make your tax return before the 31 March, for income for the preceding year. This is the recommended date, but not the final one. The real deadline, after which you risk a penalty or additional tax, is 31 December.

Note, however, that you must comply scrupulously with the 31 March date if and only if you are married taxpayers and want to change the tax regime applied to your 2023 income (for instance, change from collective to individual taxation or vice versa)!

The tax authorities send out a withholding tax card (fiche de retenue d’impôt) during January or early February. This document is sent to your employer and allows it to deduct tax at source from your salary.

The formats and how to fill in the form

The paper version (form 100F for French speakers) is still used, but is gradually being replaced by electronic exchanges.

If you go online , you have two options: you can

  • Download and fill in a PDF version of the 100 form, then send it back via
  • Fill in your form directly at the portal

In both cases, you need to login using a LuxTrust certificate, to guarantee maximum security.

Points to watch

You can claim a certain number of deductible expenses. Some examples are:

  • Necessary costs (expenses related to carrying out a salaried activity) 
  • Pensions paid to a divorced spouse, maintenance payments and other standing payments 
  • Compulsory social-security contributions and deductions 
  • Insurance contributions and premiums 
  • Premiums paid into a protect4life personal protection insurance (deduct up to €672 a year)
  • Contributions into an additional pension plan (deduct up to €3,200 a year), gifts and largesse, etc.
  • Mortgage insurance premium (deduct up to €672 a year)
  • Premiums paid into a homebuyer savings plan
  • Costs of domestic services and child care

The tax advantages of insurance products

For many taxpayers, life-assurance and pension products remain the best ways of benefitting from a series of ceilings for deductible expenses.

Insurance products in fact offer two tax advantages 

  • The premiums are deductible
  • The capital value on maturity is exempt from income tax, except for pension products

Which banking and insurance products are tax deductible?

* To benefit from the tax advantages provided in Luxembourg law, life insurance policies with a savings element must have a minimum term of 10 years.

** 2 conditions: minimum contract term of 10 years and retirement age between at least 60 and 75.

Cross-border worker

If you are a French or Belgian cross-border worker and want specific information about your obligations or possible deductions, please refer to the tax guide. (

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