Pillar Two Alert: Belgium extends first QDMTT and IIR deadlines to 30 September 2026

On 3 April 2026, the Belgian tax authorities have announced a further extension of the filing deadlines for the Qualified Domestic Minimum Top-up Tax (QDMTT) and the Income Inclusion Rule (IIR) returns until 30 September 2026.

Deadlines

Article 52 of the Belgian Pillar Two law prescribes that a QDMTT return must be submitted at the latest on the last day of the 11th month following the end of the fiscal period.

Article 57/1 of the Belgian Pillar Two law prescribes that a IIR return must be submitted at the latest on the last day of the 15th month following the end of the fiscal period beginning no earlier than 1 January 2025 and on the last day of the 18th month following the end of the fiscal period which begins no later than 31 December 2024.

For multinational enterprise groups (MNEs) with Belgian operations, the extension announced on 3 April 2026 modifies the standard deadlines based on fiscal year-end dates:

Implications for Taxpayers

The extension of the QDMTT and IIR deadlines provides for additional time for taxpayers to prepare. As of today, the Belgian Pillar Two filing platform is not yet open, and the final forms and technical instructions have not been published. The Belgian tax authorities will provide further guidance regarding the filing procedures at a later date.

Taxpayers should remain focused on their Pillar Two compliance requirements:

• GIR and GIR notification deadlines unchanged: While QDMTT and IIR returns deadlines have been extended, the GIR and GIR notification deadlines remain 30 June 2026 (for calendar year MNEs; fiscal year MNEs: 18 months after fiscal year-end). 
• International Pillar Two deadlines unaffected: This extension applies to Belgian requirements only. Other jurisdictions' Pillar Two deadlines and requirements remain unchanged. MNEs should continue to monitor and comply with all applicable deadlines in their respective jurisdictions.

How Deloitte can help

Deloitte can assist MNEs with all aspects of Pillar Two compliance in Belgium and globally.  Deloitte’s Pillar Two Agent technology is engineered to support MNEs with end-to-end compliance solution. From data collection and validation to tax return preparation and submission, the Pillar Two Agent provides transparency and efficiency through a single, cloud-based compliance and reporting technology platform.  Visit our website for more detailed information.