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What should I do if MyGuichet displays an error when I submit my tax return?

Errors on MyGuichet generally fall into two categories.

"Invalid document"

The PDF file has been modified. A simple change to the name or content is enough to render the document invalid, as MyGuichet checks the integrity of the file generated by taxx.lu.

The solution:

Go back to taxx.lu and download your PDF again.
Upload it to MyGuichet without changing the data or renaming it.
If you need to correct any information, do so directly on taxx.lu, then download the new version of the document.

A "technical error"

This is usually caused by MyGuichet’s servers. If the upload takes longer than a minute, the portal may interrupt the process and return an error message, even if your file is perfectly valid.

The solution:

Wait a few minutes, then try again.
If the error persists, try again later in the day or the following day.

If the problem does not fit any of these scenarios or persists despite your attempts, our team is available via chat or email (help@taxx.lu) to help you complete the submission.

Updated on: 28/04/2026

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