What happened?
The Belgian tax authorities have announced an extension of the filing deadline for the Qualified Domestic Minimum Top-up Tax (“QDMTT”) return and the Income Inclusion Rule (“IIR”) Top-up Tax Return. For returns for which the statutory filing deadline falls before 30 September 2026, the deadline has been extended to 30 September 2026.
The due date for the Belgian QDMTT return is extended until 30 September 2026 for taxpayers with a financial year which:
- started at the earliest on 31 December 2023, and
- ended at the earliest on 1 January 2024 and at the latest on 30 September 2025.
The final QDMTT return has not yet been published by the Belgian tax authorities. A draft version is available online. As a reminder, the deadline for filing the Belgian QDMTT return had already been extended. For more details, we refer to our newsflash.
In addition, the Belgian tax authorities have extended the due date for the IIR Top-up Tax return to 30 September 2026 for taxpayers with a financial year which:
- started at the earliest on 31 December 2023, and at the latest on 31 December 2024; and ended at the latest on 28 February 2025; or
- started at the earliest on 1 January 2025, and ended at the latest on 31 May 2025
The final version of the IIR Top-up Tax return has not yet been published by the Belgian tax authorities. A draft IIR Top-up Tax Return was published on 19 March 2026 for public consultation (comments were due by 3 April 2026).
You can find the official announcement and further details from the Belgian tax authorities here. Note that practical guidance and technical details on the filing process will follow later.
How can PwC help?
We recommend revisiting your current compliance planning and adjusting your internal timelines accordingly. While the filing deadlines for the Belgian QDMTT return and IIR Top-up Tax return have been extended, it is important to note that the GloBE Information Return (“GIR”) and the GIR notification remain due by their original deadline.
In addition, the revised timing coincides with the peak period for many corporate income tax filings, which may put additional pressure on internal resources. We would be pleased to support you with the preparation, review and/or filing of the Belgian QDMTT return and the IIR Top‑up Tax return.
Following the extension, we recommend using the additional time to align on responsibilities within your group and to start gathering the required data early, in order to ensure a timely and well‑coordinated filing process.
For more insights or advice, please reach out to your regular PwC contact, or contact Pieter Deré, Koen De Grave or Maxim Allart.
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