Belgium: Draft IIR top-up tax return published for public consultation
Stakeholder feedback is requested by April 3, 2026.
The Belgian tax authorities have published the draft IIR top-up tax return and explanatory notes (Dutch) for public consultation. Stakeholder feedback is requested by April 3, 2026 by e-mail to pillar2@minfin.fed.be.
Under the Belgian law on minimum taxation, an income inclusion rule (IIR) top-up tax return must be submitted to declare the IIR top-up tax. Each taxpayer subject to the IIR top-up tax must file its own tax return. Consequently, multiple IIR top-up tax returns may be filed for a single group. The IIR top-up tax return is a formal tax return and triggers an assessment notice by the Belgian tax authorities.
Filing deadline
The filing deadline for the IIR top-up tax return is aligned with that of the information return (the Belgian equivalent of the GloBE information return (GIR) / top-up tax information return (TIR)). The deadline is the last day of the 15th month following the fiscal year, but the first filing deadline is extended to the last day of the 18th month following the fiscal year that begins at the latest on December 31, 2024. When the fiscal year coincides with the calendar year, this means that for fiscal year 2024 the first filing deadline is June 30, 2026.
Read a March 2026 report prepared by the KPMG member firm in Belgium