Additional postponement of Pillar II returns

On December 19, 2023, the federal parliament approved the introduction of the new minimum tax in Belgium for companies. Through this legislation, the government intends to impose a minimum tax rate of 15 percent on companies that are part of large (international) groups in each country where they operate. This new minimum tax applies to reporting years beginning on or after December 31, 2023.

In this context, the same law imposes several annual compliance obligations on large groups. The first tax return filing requirement relates to the domestic top-up tax, known as Qualified Domestic Minimum Top-up Tax (“QDMTT”). This QDMTT return must be filed within eleven months of the closing date of the reporting year corresponding to the financial year of the ultimate parent company filing the consolidated financial statements.

As a result, the very first QDMTT return (with respect to reporting years starting from December 31, 2023) was originally due by November 30, 2025. However, as there were (and still are) many uncertainties regarding the practicalities of this declaration formality, an initial postponement applied until June 30, 2026.

A second filing requirement relates to the top-up tax based on the Income Inclusion Rule (“IIR”). Based on the applicable legislation, this return must be filed on the last day of the eighteenth month following the end of the reporting year beginning no later than December 31, 2024, or on the last day of the fifteenth month following the end of the reporting year beginning no earlier than January 1, 2025. De facto, this meant that the first possible IIR returns had to be filed by June 30, 2026.

On April 3, 2026, the Belgian tax authorities granted additional extensions for both the QDMTT and IIR filing deadlines, through September 30, 2026.

Specifically, this includes that:

• The QDMTT return for reporting years starting at the earliest on December 31, 2023 and ending no later than September 30, 2025 must be filed by September 30, 2026;
• The IIR return for reporting years starting at the earliest on December 31, 2023, and ending no later than May 31, 2025, must be filed by September 30, 2026.

The tax administration did not communicate an underlying reason for this additional postponement of compliance formalities. Since there is still no (final) practical guidance or technical documentation available regarding the return templates and procedure, the cause can probably be sought therein.

In the meantime, both the QDMTT and IIR returns are already available on the FPS Finance website, though only in draft form and not as final versions.

However, companies subject to Pillar II rules cannot rest on their laurels due to the announced extension. Indeed, by June 30, 2026, they must file the GloBE Information Return (“GIR”) or a GIR notification. The GIR constitutes the central information return under the Pillar II legislation and contains all the core information needed to calculate the effective tax rate (‘ETR’) by jurisdiction under the GloBE rules. These rules form the basis for determining any top-up tax.

In principle, the GIR must be filed by the Ultimate Parent Entity (‘UPE’) of the group to which the Belgian entity(ies) belong(s). However, the UPE can transfer this filing obligation to an intermediate parent entity or another designated group entity. If the UPE or designated filing entity is not established in Belgium, filing a GIR notification in Belgium should be sufficient.

Today, there is no information available in Belgium on the specific implementation of this compliance obligation, in particular on the procedure and the return template. This aspect was also not highlighted in the Belgian tax authorities’ recent communication regarding the postponement of QDMTT and IIR returns.

Due to the supplementary postponement of Pillar II returns until September 30, 2026, these filing deadlines coincide with the statutory deadline for filing the corporate income tax return and the Local File for companies with a financial year that closes on 31 December 2025.

We recommend that taxpayers align their internal deadlines with this timing to ensure smooth and efficient handling of the various compliance obligations. Taking into account the coincidence of these different tax return obligations, a compliance bottleneck seems inevitable. Therefore, it is important to gather the necessary information on your company’s Pillar II obligations well in advance.