Belgium has extended the supplementary national tax return filing deadline from the 11th to the 15th month following the fiscal year close, with an 18th month extension for fiscal years beginning by 31 December 2024. The Finance and Budget Committee approved the amendment on 2 October 2026, modifying the Law of 19 December 2023 and transposing Council Directive (EU) 2025/872.
Belgium’s tax authority (FPS Finance) announced that it adopted a legislative amendment that postpones the deadline for filing supplementary national tax returns. The Finance and Budget Committee approved the change on 2 October 2026, under document reference DOC 56 1719/003.
The Belgian authorities previously announced a postponement of these filing deadlines on 28 September 2026. The current legislative amendment formalises this extension through a draft law designed to transpose Council Directive (EU) 2025/872 of 14 April 2025 into Belgian law.
The amendment modifies the Law of 19 December 2023, which introduced the minimum tax framework for multinational enterprise groups and large national groups.
New filing deadlines established
The Law of 19 December 2023 currently mandates that the supplementary national tax return be filed by the last day of the 11th month following the close of the fiscal year. The new amendment extends this timeline significantly.
Filing deadlines now operate as follows: the standard deadline moves to the last day of the 15th month following the fiscal year close. For fiscal years beginning no later than 31 December 2024, a temporary extension applies, extending the deadline to the last day of the 18th month following the fiscal year close.
Alignment with EU directive requirements
The amendment fulfils Belgium’s obligation to align domestic tax law with Council Directive 2011/16/EU on administrative cooperation in taxation. Council Directive (EU) 2025/872 of 14 April 2025 amended the 2011/16/EU directive, requiring Member States to adjust their procedures accordingly.
Entry into force
The legislative amendment will take effect on the date of its publication in the Belgian Official Gazette. The Finance and Budget Committee’s approval on 2 October 2026 represents the final step before this publication occurs.
