Filing an income tax return for natural persons via the electronic assistant on MyGuichet.lu
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Summary:
If you fill in your income tax return using the electronic assistant on MyGuichet.lu, it will be processed automatically. This means that no intervention by an agent of the Luxembourg Inland Revenue (ACD) is required. The main objective is to speed up and streamline the taxation procedure. Despite automated processing, these declarations may be subject to subsequent checks by an ACD agent for a period of 5 years.
Resident and non-resident taxpayers who are subject to taxation (taxation by assessment) in Luxembourg are required to report their income by filing an income tax return (form 100). Should they not be liable for tax, they may nevertheless file a tax return to be taxed by means of an assessment upon request.
If you are part of the target audience, you can, as of the 2021 tax year, file your income tax return online via an electronic assistant on the secure MyGuichet.lu platform. Some of the advantages of using the assistant are:
- you can fill in and submit your tax return directly online on MyGuichet.lu, without having to fill in a PDF form;
- the assistant guides you step by step and adapts according to your answers;
- you can benefit from automatic data insertion, explanatory tooltips and improved ergonomics.
- the tax return is processed automatically without direct intervention by an ACD agent, which allows for faster feedback.
Who is concerned
Taxpayers concerned
All resident or non-resident persons who:
- are subject to a tax return obligation following a request from the Luxembourg Inland Revenue (ACD); or
- wish to file a tax return upon request.
Types of income to be reported
As of the 2024 tax year, all income categories can be declared using the electronic assistant.
Cases in which the electronic assistant may not be used
You may not use the electronic assistant if you:
- have been married more than once during the tax year;
- have changed country of residence during the tax year;
- do not have the same country of residence as your spouse/partner in the case of joint taxation;
- request a tax regularisation by annual adjustment;
- revoke joint taxation by assimilating the non-resident to the resident.
If the 'withholding tax forms' of a non-resident couple show a tax rate, then this couple can use the electronic assistant because the assimilation mode has already been requested in advance as the rate has been entered on the withholding tax form.
Furthermore, you cannot use the electronic assistant to request or after having previously requested:
- joint taxation upon joint request made by a resident taxpayer and a non-resident taxpayer, who do not live de facto separated, provided that the resident taxpayer earns at least 90 % of the household's professional income during the tax year in Luxembourg;
- purely individual taxation or taxation with reallocation of adjusted joint taxable income.
Beginning with the 2024 tax year, you will have to answer a series of questions to determine whether you can file your income tax return using the online assistant. If you cannot use the online assistant, you can file your income tax return by sending in 'form 100' (to be downloaded under 'Online services and forms' below or from the ACD website):
- electronically via the MyGuichet.lu procedure dedicated to PDF submissions; or
- by post to the relevant tax office.
Prerequisites
MyGuichet.lu account
If you wish to complete your tax return using the electronic assistant, you will need:
- a 13-digit national identification number (matricule); and
- a LuxTrust product or a Luxembourg electronic identity card (eID) in order to:
- create a MyGuichet.lu account; and
- sign your tax return electronically.
If the declarant is the taxpayer or if they are acting as a private proxy (for example, they are completing the tax return for their parents), they must have a private eSpace.
If the taxpayer's proxy is a professional (e.g. a fiduciary or a lawyer), they must have a business eSpace.
Power of attorney
If the tax return is submitted by an authorised proxy, the latter must have a power of attorney from the taxpayer. In the case of the tax return, they must attach a power of attorney - form 101 (see 'Online services and forms') to the tax return.
This power of attorney is not required if the proxy is a lawyer.
Deadlines
Regardless of how you file your tax return (electronically or by post), you must submit it by 31 December of the year following the tax year in question at the latest.
Example: for tax year N, the tax return is due by 31 December of year N+1 at the latest.
For the 2024 tax year, the tax return submission period therefore runs from 7 April 2025 to 31 December 2025.
You must always respect the specific deadlines for correspondence sent by the various ACD departments. In the event of failure to comply with the stated deadlines, the tax office may apply:
- supplementary taxes;
- late payment interest; or
- a penalty payment.
Taxpayers who refuse to file their tax return will force the tax office to determine the tax liability using the estimated assessment procedure (taxation d'office par voie d'estimation).
How to proceed
Submitting the application
Taxpayers or their proxies (e.g. a fiduciary), must submit the income tax return for natural persons electronically through their private or business eSpace on the MyGuichet.lu platform.
The ACD has created a series of tutorials as part of its 123easy campaign, which provide more information on how to fill in your tax return using the electronic assistant on MyGuichet.lu.
To speed up the declaration process, it can be initiated by uploading an XML file to MyGuichet.lu.
After initiating the procedure, the declarant is invited to follow the instructions provided by the assistant in order to complete the tax return.
Electronic signature
Tax returns submitted via the electronic assistant on MyGuichet.lu require a signature with an electronic authentication and signature certificate stored in:
- a LuxTrust product; or
- a Luxembourg electronic identity card (eID).
The electronic signature cannot be performed with an eIDAS means of identification from another country.
Our tutorial uses screenshots to explain step by step how to sign and submit a procedure with authentication.
Specificities in the event of joint taxation
If the tax return is not submitted by an authorised proxy, a double electronic signature is required in the case of joint taxation. Two situations may arise:
- both taxpayers have their own certificate;
- one of the 2 taxpayers does not have their own certificate.
- Scenario 1
- Scenario 2
If both taxpayers have their own certificate, a double signature with transfer to another eSpace will be required as from the 2024 tax year. This means that the taxpayer who is the first to sign the tax return in their private eSpace must send it to the private eSpace of their spouse/partner so that they can also add their signature using their own certificate.
Unlike previous years, the spouse/partner will therefore also need a private eSpace on MyGuichet.lu as from the 2024 tax year.
To send the declaration to your spouse's/partner's private eSpace, you will need their eSpace identifier. To find out where to find this identifier, see our help article on this subject.
Our tutorial uses screenshots to explain step by step how the double signature with transfer works.
If one of the taxpayers does not have their own certificate, it is possible to use the declarant taxpayer's certificate for both signatures. In order to do this, when entering the information in the electronic assistant, you must first indicate under 'Indications générales - Mandataire contribuable conjoint/partenaire' (general information - proxy for the taxable spouse/partner) that the joint taxpayer/partner has a representative.
Next, under 'Indications générales - Mandataire contribuable conjoint/partenaire – Détail' (general information - proxy for the taxable spouse/partner - details), you must indicate that the declarant taxpayer acts as the representative of the joint taxpayer/partner.
In this case, the taxpayer making the declaration (i.e. the holder of the certificate) must attach the power of attorney - form 101 (see 'Online services and forms') for their spouse/partner to the tax return.
In our tutorial we explain in more detail how the double signature works if one of you does not have a certificate.
If it has not been explicitly stated that the taxpayer is the authorised proxy for their spouse/partner, signing twice with same certificate twice is not authorised and an error message will appear on MyGuichet.lu.
Attachments
If you use the electronic assistant, the documents that must be attached to your tax return are selected based on your answers.
In our tutorial, we use screenshots to explain, step-by-step, the different ways of adding attachments to a procedure with authentication.
Obligations
You must:
- declare the income of all persons who are jointly taxable (all amounts must be declared in EUR);
- give your consent to the exclusively automated processing of the electronic income tax return.
You may withdraw your consent at any time. Withdrawal of consent can be made by letter to the competent tax office until the tax has been accounted for.
In the case of joint taxation, the withdrawal of consent by one of the spouses is sufficient to ensure that taxation cannot be carried out exclusively by automated means.
Taxpayers who do not wish to give their consent to exclusively automated processing can file their income tax return using 'Form 100' (which can be downloaded from 'Online services and forms' or the ACD's website):
- electronically via the MyGuichet.lu procedure for PDF submissions; or
- by post to the relevant tax office.
Tutorials
Key features of MyGuichet.lu
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Registering on MyGuichet.lu and setting up a private eSpace
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Setting up a business eSpace
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Adding attachments to a procedure with authentication
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Signing and sending a procedure with authentication
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Signing and submitting our tax return electronically (without a private mandate)
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Signing and submitting our tax return electronically (with a private mandate)
Tax year 2024
Online services and forms
Who to contact
Tax questions
-
Contact Centre - Luxembourg Inland Revenue (ACD)
- Address:
- 33, rue de Gasperich L-5826 Hesperange Luxembourg
Technical questions concerning the electronic assistant on MyGuichet.lu
-
Guichet.lu Helpdesk
- Address:
- 11, rue Notre-Dame L-2240 Luxembourg
- Phone:
-
(+352) 247 82 000
Our Helpdesk can be reached by telephone on working days from 8.00 to 18.00.
You can also book an appointment for a video call via MyGuichet.lu.
Please note that the Guichet.lu Helpdesk provides general information on administrative procedures. It does not have access to the files you have submitted to a public body in Luxembourg. If you have specific questions, the Helpdesk will direct you to the appropriate administration.
Related procedures and links
Procedures
Links
Further information
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123easy!
Official website of the Luxembourg Inland Revenue (ACD) on the electronic assistant
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Calculatrice fiscale
sur le site du ministère des Finances
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Délais
sur le site de l'Administration des contributions directes (ACD)
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Dépôt/Remise
sur le site de l'Administration des contributions directes (ACD)
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Formulaires pour les personnes physiques
sur le site de l’Administration des contributions directes (ACD)
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Imposition par voie d'assiette (impôt sur le revenu)
sur le site de l'Administration des contributions directes
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Service d’imposition - Section des personnes physiques
sur le site de l’Administration des contributions directes (ACD)
Legal references
concernant l'impôt sur le revenu
