The 2026 guide to filing your tax return in Luxembourg

Filing a tax return is an important annual step for every taxpayers, whether they are Luxembourg residents or cross-border workers. In many cases, it is not mandatory (due to withholding tax) but is often beneficial. In 2026, several changes and tax relief measures come into effect, simplifying the process for many taxpayers. Here is a comprehensive guide to help you complete your tax return with ease.

Steps and deadlines for filing your tax return

1. Receiving the form: forms and online services will be available from 7 April 2026 on MyGuichet.lu. If you do not receive a paper form or an online filing invitation, you can still submit your tax return.
2. Gathering necessary documents: ensure you have all supporting documents related to your income and deductible expenses (for example, the "Wage Statement" provided by the employer in the first quarter of the current year).
3. Completing the Model form 100: this form is essential for declaring your income and benefiting from possible tax deductions.
4. Submitting your tax return: it is essential to ensure that the declaration is submitted before 31 December 2026.
5. Tax calculation: the tax administration will determine the amount of tax you owe based on your income, deductible expenses, and family situation.

Filing methods

• Paper version: fill in the form provided by the tax authorities and submit it to your tax office or send it by post;
• Online: use the MyGuichet.lu portal for a faster and easier process (log in using LuxTrust or GouvID or eIDAS).

Penalties

• Late submissions will result in penalties and interest charges (fine of up to €25,000, a tax surcharge of 10% to 20% depending on the delay);
• Extensions may be requested if necessary;
• Online filing allows for faster processing, with tax calculations available within 15 days.

Key tax changes in Luxembourg for 2026

1. Tax allowance for maintaining employment (abattement pour maintien dans la vie professionnelle, AMVP): A tax allowance of up to €9,000 per year for taxpayers who satisfy the statutory conditions, intended in particular to encourage continued participation in the labour market instead of early retirement.
2. Alternating residence of children: Introduction of a tax advantage of up to €922.50 per child for taxpayers with alternating residence of their children. For parents who aren't part of the 1A tax class.
3. Pension savings scheme (article 111bis): Increase of the maximum deductible amount from €3,200 to €4,500 per taxpayer as from the 2026 tax year (an increase of 41%), thereby potentially enhancing the tax relief available to taxpayers who pay into a private pension savings product qualifying under article 111bis of the Income Tax Law.

Discover what's new in the job market in 2026.

By following these guidelines, whether you are a Luxembourg resident or a cross-border worker, you can ensure an optimal tax declaration process and avoid any fiscal inconveniences.

Want to easily generate your tax return? Taxx.lu is an online platform designed to simplify tax filing for individuals in Luxembourg. Paid service: €59.

For more details or any specific questions, please refer to the Frontaliers.lu tax guide (only available in French).

Learn more about labour laws and working conditions in Luxembourg.