Overview

On 19 March 2026, the Belgian Tax Authorities published a draft Income Inclusion Rule (IIR) return template, together with accompanying guidance (link: Publieke consultatie - Aangifte IIR-bijheffing | FOD Financiën). In addition, on 23 March 2026, a slightly updated Qualified Domestic Minimum Top-up Tax (QDMTT) return was released, together with accompanying guidance (link: Aangifte binnenlandse bijheffing | FOD Financiën). The rollout of these draft templates, and their accompanying draft guidance, provides helpful insights into the expected reporting framework and represents a next step in the operational rollout of the Pillar Two compliance in Belgium. Finally, an amendment to the Belgian Pillar Two Circular Letter was issued, clarifying the conversion of foreign currencies, which is also relevant when preparing these Pillar Two returns (link: MyMinfin).

Draft IIR return and guidance

As a reminder, an IIR tax return is a tax filing through which an IIR taxpayer (typically the Ultimate Parent Entity (UPE), an Intermediate Parent Entity (IPE) or a Partially Owned Parent Entity (POPE)), reports low-taxed income of its directly or indirectly held low-taxed entities.

The draft guidance confirms that each taxpayer liable for IIR Top-up Tax must annually file its own return and hence, more than one IIR Top-up Tax return may need to be filed in Belgium for an in-scope group. Similar to the QDMTT return, the IIR Top-up Tax return is a formal tax return triggering the issuance of an assessment notice by the Belgian Tax Authorities, contrary to the GloBE Information Return (GIR) which is an information report that enables the exchange of relevant Pillar Two information among the different tax authorities.

The draft guidance states that an IIR return must be filed by all group entities established in Belgium referred to in Article 31, Section 1 of the Belgian Pillar Two Law, insofar as they are not excluded under Article 31, Section 2 or Section 3. This implies that, for example, a Belgian IPE held by a UPE located in a jurisdiction that implemented a qualifying IIR would be exempt from filing an IIR return in Belgium. The draft guidance is written in such a manner that the requirement to file an IIR return is linked to the status of being an IIR taxpayer, irrespective of whether an IIR Top-up Tax is due (e.g., due to the availability of a safe harbor).

The datapoints to be disclosed in the IIR return largely align with those provided in the GIR; however, the Belgian IIR return still requires some Belgium-specific datapoints, such as information related to Belgian advance tax payments.

The IIR return must be filed within 15 months after the end of the relevant fiscal year, extended to 18 months for the first fiscal year in which the group falls within the scope of Pillar Two. For calendar-year taxpayers, this means that the first due date for filing the IIR return will be 30 June 2026.

The Belgian Tax Authorities have launched a public consultation round for the draft IIR tax return. Groups in scope of Pillar Two should review the draft materials carefully and are invited to share their comments with the Belgian Tax Authorities by 3 April 2026 via e-mail to the following e-mail address: pillar2@minfin.fed.be.

Updated draft QDMTT return and guidance

In addition to the publication of the draft IIR return template, the Belgian Tax Authorities also published a new draft version of the QDMTT return template. The latest version includes limited changes from the previous draft, including the deletion of certain elections and the inclusion of explicit legal references in several computation fields.

Draft versions of the corresponding XSD schema, related code lists and an updated test XML tool have also been released on an informational basis, alongside updated draft accompanying guidance for the return, all of which remain subject to change until formally finalized and published in the Belgian Official Gazette.

Circular letter on currency conversions

Finally, the Belgian Tax Authorities also recently published an addendum to the Pillar Two Circular Letter specifically dealing with currency conversions and clarifying how amounts expressed in a currency other than the euro should be converted when testing euro-denominated thresholds, or how Top-up Tax calculated in a non-euro currency should be translated into euros.

In this respect, when filing local Pillar Two returns in Belgium, for purposes of computing the Top-up Tax liability, amounts expressed in a presentation currency different than the euro should be translated into euros using the exchange rate applicable on the last day of the relevant Fiscal Year. The exchange rate to be applied is the reference exchange rate published by the European Central Bank. This currency conversion approach applies consistently to all Top-up Taxes — i.e., for the Top-up Tax levied via the QDMTT, IIR and UTPR.

Next steps

In view of the upcoming 30 June 2026 deadline, in-scope taxpayers should be prepared to finalize and file the various Belgian Pillar Two to avoid a last-minute rush. It is expected that the return templates, including the ones related to the GIR and the GIR notification (neither of which has yet been published) will be finalized soon.

Affected groups should consider engaging tax advisors for assistance with compliance obligations and last-mile support.