2026 Income Tax Return: How to Correct an Error

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Have you noticed a mistake in your 2026 income tax return? Perhaps you forgot to declare certain income or entered incorrect information. Whether you submitted your tax return online or by paper form, you can request a correction. Here is what you need to know.

If You Filed Your Tax Return Online

Correcting Your Return After Receiving Your Tax Notice

Your tax notice will be available in your personal tax account between July 24 and July 31, 2026.

If you discover an error after receiving your notice, you can use the online correction service available in your Public Finances account through the “Access Online Correction” feature. This service will be open from July 29, 2026, until the end of November 2026.

During this period, you can:

  • Review your submitted tax return.
  • Correct declared amounts.
  • Modify boxes that were incorrectly checked.

Once your correction request is submitted, you will receive a confirmation email. After the tax administration processes the amended return, a new tax notice will be issued, and your withholding tax rate will be updated accordingly.

After the Online Correction Period Ends

Once the online correction service closes, any modification request must be made through a formal claim submitted from your personal tax account.

These claims are subject to specific deadlines. Taxpayers should review the applicable time limits for tax-related complaints and appeals before filing a request.

Important Information

Some details cannot be modified through the online correction service, including:

  • Changes in family status such as marriage, civil partnership (PACS), separation, divorce, or death.
  • Updates to civil status information.
  • Changes concerning the designation of a trusted third party.
  • Address modifications.
  • Adding or updating a student’s address.

If You Filed a Paper Tax Return

If you submitted a paper declaration, you can request a correction after receiving your tax notice.

Online Procedure

You may submit your claim through the secure messaging service in your Public Finances account by selecting:

Write → Complaint/Dispute → Income Tax

By Mail

You may also send a written request to your local Public Finance Center. Your letter should include the following information:

  • Full name and address.
  • Tax identification number.
  • Handwritten signature.
  • The tax concerned by the claim.
  • A detailed explanation of the issue, along with supporting documents.

Reminder: The Right to Make Mistakes

Taxpayers who make an error in a declaration submitted to the administration may benefit from the right to make mistakes.

This principle allows individuals to correct an unintentional error and regularize their situation without automatically facing a penalty, provided the correction is made in accordance with the applicable rules and procedures.