Pillar Two in Belgium: Filing Deadlines Extended to 30 September 2026

The EU transposed these rules through Council Directive (EU) 2022/2523 of 14 December 2022. Belgium implemented the Directive by way of the Law of 19 December 2023 (the “Belgian Pillar Two Law”), as amended by the Law of 12 May 2024. The rules apply to MNE groups and large-scale domestic groups with consolidated annual revenues of at least EUR 750 million in at least two of the four preceding fiscal years.

How does it work?

The effective tax rate (ETR) is calculated on a jurisdictional basis : for each country where the group has constituent entities, the covered taxes are divided by the qualifying income (GloBE income). Where the ETR in a given jurisdiction falls below 15%, the difference generates a top-up tax.

The central question is then: which jurisdiction collects this top-up tax? The GloBE rules address this through three mechanisms, which apply in a specific order of priority:

• The Qualified Domestic Minimum Top-up Tax (QDMTT) has priority. It allows the jurisdiction where the low-taxed entities are located to collect the top-up tax itself, before any other jurisdiction can do so. Belgium has adopted a QDMTT for this reason : it ensures that any Belgian top-up tax revenue remains in Belgium rather than being collected by the jurisdiction of the parent entity.
• The Income Inclusion Rule (IIR) applies next. It works top-down: the ultimate parent entity (UPE) is liable for the top-up tax on the low-taxed income of its foreign subsidiaries, to the extent that a QDMTT has not already captured the tax in the source jurisdiction. If the UPE is not located in a jurisdiction that applies the IIR, the obligation moves down to intermediate parent entities.
• The Undertaxed Profits Rule (UTPR) acts as a backstop. It only applies where neither the QDMTT nor the IIR has collected the top-up tax – typically because the UPE is located in a jurisdiction that has not implemented Pillar Two (such as the United States). The UTPR allocates the residual top-up tax to other jurisdictions within the group, based on the substance present in each (employees and tangible assets).

Filing obligations

In-scope groups with Belgian constituent entities must comply with several annual filing requirements :

• QDMTT return (Art. 52 of the Belgian Pillar Two Law) – due within 11 months after the end of the fiscal year. Filing is mandatory regardless of whether a top-up tax is actually due or whether the transitional CbCR safe harbours apply.
• IIR return (Art. 57/1) – due within 18 months after fiscal year-end for the first in-scope year, and within 15 months for subsequent years.
• GloBE Information Return (GIR) – a comprehensive return containing the effective tax rate (ETR) calculations and top-up tax determinations per jurisdiction. Must be filed by the Ultimate Parent Entity (UPE) within the same timeframe. A GIR notification is also required.

Extension of the filing deadlines

Given the practical challenges surrounding these first-ever filings, the Belgian Tax Authorities have granted two successive deadline extensions.

On 17 November 2025, the Federal Public Service of Finance (SPF Finance) extended the QDMTT return deadline to 30 June 2026, aligning it with the GIR deadline and with the QDMTT filing dates applicable in most other EU Member States.

On 3 April 2026, a further extension was granted. All QDMTT and IIR returns whose statutory deadline would otherwise fall before 30 September 2026 are now uniformly deferred to 30 September 2026. The SPF did not communicate an explicit reason, but the extension is most likely linked to the fact that the return templates and the accompanying practical guidance have not yet been finalized.

This is a one-time extension. For subsequent fiscal years, the standard statutory deadlines remain in force: 11 months for the QDMTT return, 15 months for the IIR return. The GIR filing deadline remains unchanged at 30 June 2026 for calendar-year groups.

How we can help

The extension to 30 September 2026 offers additional time, but it does not reduce the scope or complexity of the underlying obligations. The new deadline coincides with the annual corporate income tax return and Local File filing deadlines for calendar-year companies, and the return templates remain in draft.

Our international tax team at Andersen in Belgium has the expertise to guide your group through the full Pillar Two compliance process. For further information or to discuss your Pillar Two compliance needs, please do not hesitate to contact us.