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The ACD will propose to eligible taxpayers a tax return based on known information. This simple tax return proposal includes the identification data and tax data known to the ACD, which are the salaries and/or pensions of each taxpayer.

As its name suggests, the purpose of the simple tax return is to simplify the procedures for taxpayers, allowing them to save time, because they no longer need to complete a tax return. Taxpayers need only to check the information already pre-filled.

If the information provided in the simple pre-filled tax return is inaccurate or incomplete, simply disregard the letter and file your income tax return using one of the available alternative methods, such as: ​

• electronic submission via the MyGuichet platform (using the “ACD (Form 100)” or “ACD (Form 100) – (PDF submission)” option) or​
• paper submission using Form 100. ​

Who is affected by this procedure? This year: taxpayers who are required to file an income tax return (Form 100) and whose income consists solely of  “salary and pension” income, with:​​

A - Flat-rate minimum or ceiling for special expenses covered by the flat-rate minimum related to: ​

• Interest expense (related to consumer loans for financing cars, personal property, etc.)​
• Insurance premiums and contributions:​

1. Premiums paid for life, death, accident, disability, health, or liability insurance to licensed insurance companies headquartered in a European Union member state (premiums related to the following risks are not deductible: property damage, theft, fire, glass breakage, comprehensive coverage, etc.)​
2. Contributions paid to recognized mutual aid societies whose purpose is to insure against the risks of illness, accident, inability to work, disability, unemployment, old age, or death​

• Arrears of annuities and permanent expenses (paid to a divorced spouse)​

​B - Extraordinary expenses related to:

• Flat-rate deductions: Disability and infirmity ​

The profile of eligible taxpayers will be gradually expanded over the coming years. This selection will be reassessed annually based on changes in tax situations.​

On March 30, eligible taxpayers receive by post a simple pre-filled tax return for the 2025 tax year. This letter was generated using the information available to the tax authorities at the time of mailing.

After receiving the simple pre-filled tax return, the taxpayer is asked to:
1. review the information on the return and, when applicable,
2. sign the return, and
3. return the simple pre-filled tax return by post to the relevant tax office. The relevant tax office is indicated at the end of the cover letter.

If the information provided in the simple pre-filled tax return is inaccurate or incomplete, simply disregard the letter and file your income tax return using one of the available alternative methods, such as submitting it electronically via the MyGuichet platform (using the “ACD (Form 100)” or “ACD (Form 100) – (PDF submission)” or on paper using Form 100.

The electronic assistant is a tool that allows you to complete your tax return directly online on MyGuichet.lu.

The benefits of the electronic assistant are numerous:

• it guides you step by step and adapts to your anwers;
• it pre-fills your salary and/or pension details;
• it offers automatic deferrals, explanatory tooltips and improved ergonomics;
• you no longer need an additional software such as Adobe Acrobat Reader

Filing an income tax return for natural persons via the electronic assistant on MyGuichet.lu

Every tax return is unique, but a little preparation can help you complete it more quickly. It is advisable to gather and organize all relevant documents in advance, such as your annual salary or pension statements, insurance statements, interest records, and other relevant documents, so you have them readily available.

The electronic assistant will guide you step by step in filling out the correct fields. A tax return with salaries or pensions can typically be completed in less than an hour. Depending on your income sources, it may take longer, but once you have completed it once, the process becomes will become quicker in the future.

Additionally, certain fields for previous year (N-1) will be automatically pre-filled in the future.  In many cases, you will only need to update specific amounts. For example, for third-party liability insurance, the line for N-1 is automatically saved for year N, so you only need to update the amount.

You need access to a personal space MyGuichet on the site guichet.lu.
To register on MyGuichet.lu, you must have:

• a 13-digit Luxembourg national identification number (Matricule); and
• an email address; and
• your own authentication device, i.e.:
  • a LuxTrust product; or
  • a Luxembourg electronic identity card (eID); or
  • an eIDAS device from another European country.

Pre-filling is only done in cases where the ACD has sufficient individual data and in compliance with the rules relating to the protection of personal and sensitive data.

For the moment, pre-filling is offered individually to each person in his or her MyGuichet space, and not to spouses/partners.

The ACD and the CTIE are working on expanding the functionalities to offer the possibility of mandates between spouses/partners.

Upon receipt, please kindly sign and return it if everything is correct.

The deadline for its return is December 31, 2026.

Please find below a summary table of the key dates.

Only eligible taxpayers receive an invitation for a simple pre-filled tax return.

If you have not received a letter, you are not eligible for the simple pre-filled tax return and you must file your tax return by December 31, 2026 at the latest using the existing alternative channels, that are via the electronic assistant MyGuichet: ACD procedure (Model 100) or MyGuichet: ACD procedure (Model 100) – (PDF submission) or using the paper form.

The eligibility criteria are determined from the year N-1.

Starting from the tax return 2024, you need to answer a series of questions to verify your eligibility for the online electronic tax assistant. If you do not meet the criteria, you will be redirected to a PDF or a paper declaration.

Here is a list of cases where you are not eligible:

• If you have no LuxTrust product
• If you have no national registration number
• For non-residents, if you want to revoke a previously filed request for collective taxation via assimilation
• For couples, if you request individual taxation
• If you have been married more than one during a year
• If you and your spouse live in different countries
• If you changed your country of residence during the year

We have a helpline dedicated exclusively to questions about filing tax returns using the MyGuichet electronic assistant.

We will guide you through the process live. Our staff are there to:

• explain each field, even the most technical ones;
• help you avoid common errors;
• answer any other questions you may have about filling an income tax return via the electronic assistant on MyGuichet.lu.

Please note that the ACD does not act as an independent tax advisor.

If you have any other questions, please do not hesitate to contact us using the contact form: Contact form