Posted on 26 February 2024

What are the differences between Form 100 and Form 163?

When it comes to fulfilling your tax obligations in Luxembourg, choosing the right form is essential to ensure an accurate and complete declaration of your income and expenses. 

The system is there to guide you through this process by telling you, after payment, which form to send depending on your tax situation!

Form 163 and Form 100: Understanding the differences

Forms 163 and 100 are tax return documents that allow you to declare your deductible income and expenses, as well as claim refunds or settle outstanding tax debts. Despite their differences in format and complexity, choosing between form 163 and form 100 in no way affects the final tax result.

It is crucial to note that only one of the two forms, Form 163 or Form 100, needs to be sent.

  • Form 163: This is a concise 6-page version, also known as the "annual statement".
  • Form 100: A more detailed 20-page document known as a "tax return".

How do I choose between form 163 and form 100?

Choosing the right form depends on the complexity of your tax situation.

You should complete form 100 in the following cases:

  • When the household's taxable income exceeds 100 000 € per year.
  • If you earn more than 36 000 € for taxpayers in tax classes 1 and 2, and 30 000 € for taxpayers in tax class 1a.
  • For Luxembourg non-residents taxed at a flat rate.
  • If your taxable income in Luxembourg is not subject to withholding tax, for example, income from the exercise of a liberal profession, property rental, salary income paid by a foreign employer, etc.

If none of the above conditions are met and the tax authorities do not specifically ask you to submit form 100, choose form 163.

Using Form 163

Form 163, or "Annual Statement", is a simplified tax return option. It is recommended in the following situations:

  • When a student starts their professional career during the year.
  • If the taxpayer, employee or pensioner, has periods of variable or zero monthly remuneration during the year.
  • If a non-resident employee works in Luxembourg for less than 9 consecutive months during the tax year.
  • In the event of a change in family circumstances resulting in a tax change, such as the birth of a child.

Form 163 must be sent to the RTS office. To find out which RTS office you belong to, use the simulator available here:


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Create an account, complete your return and simulate your tax refund!

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