Pillar 2: New Amendments to the GMCTR and Approval of Form 64

Ordinance 318/2026/1 of July 30, approving the top-up tax assessment return (Form 64) and the corresponding completion instructions, has been published as part of the Global Minimum Tax Regime (“GMCTR” or Pillar II) applicable to multinational enterprise groups and large-scale national groups covered by global minimum taxation rules.

The approval of Form 64 is another significant step in the practical implementation of the GMCTR in Portugal and completes the operationalization of the main reporting obligations established in article 45.1 of the GMCTR.

The GMCTR was approved by Law 41/2024 of November 8, which transposed into national law Council Directive (EU) 2022/2523 of 14 December 2022 on ensuring a global minimum level of taxation for multinational enterprise groups and large-scale domestic groups in the Union.

Under article 45.1 of the GMCTR, constituent entities located in Portugal belonging to groups covered by the regime may be subject to three main reporting obligations: (i) the registration form, (ii) the top-up tax information return, corresponding to the GloBE Information Return (“GIR”), and (iii) the top-up tax assessment return.

The first of these obligations (submitting the registration form) had already been operationalized through Ordinance 290/2025/1 of September 2, which approved Form 62 and the corresponding completion instructions. The general purpose of this form is to report the start of the group’s international business activity or the first tax year in which the large-scale national group comes within the regime, as well as to identify the entity responsible for complying with certain reporting obligations.

In the meantime, Law 26/2026 of June 3 introduced the first amendment to the GMCTR, transposing into Portuguese law Council Directive (EU) 2025/872 of 14 April 2025 or DAC 9, which amends Directive 2011/16/EU on administrative cooperation in the field of taxation.

This amendment is particularly relevant in the context of the GIR. It clarifies that there is no obligation to submit the top-up tax information return locally in Portugal when Form 62 indicates that the group’s GIR will be submitted centrally in the jurisdiction where the group is located. In that case, the GIR must be submitted by the ultimate parent company or by the group’s designated reporting entity. This applies provided that the entity is located in a European Union Member State that applies a qualified income inclusion rule (IIR), a qualified undertaxed profits rule (UTPR), or a qualified domestic top-up tax for the tax year concerned. It also applied if the entity is located in a country or jurisdiction that has entered into a qualified competent authority agreement with the Portuguese competent authority for that tax year.

Ordinance 255/2026/1 of June 12 has also been published and approves Form 63 concerning compliance with the reporting obligation established in article 45.1(b) of the GMCTR. Form 63 must be submitted electronically as an XML file with the characteristics and structure described on the Portuguese Tax Authority’s website.

The recent approval of Form 64 operationalizes the third reporting obligation established in article 45.1(c) and 45.3 of the GMCTR, that is, the submission of the top-up tax assessment return.

The purpose of this tax assessment return is to calculate the top-up tax payable in Portugal by constituent entities located in Portuguese territory, or by the designated local entity of the groups concerned when this designation has been previously reported using Form 62. According to the completion instructions, these entities are not required to submit this return when there is no top-up tax to be paid in Portugal.

Form 64 requires the group’s top-up tax information return (GIR/Form 63) to be identified by jurisdiction, submission date, and respective number. This reinforces the need for global coordination in complying with the reporting obligations applicable to groups covered by the GMCTR.

Finally, Order 76/2026-XXV of June 3 extended the deadline – established in article 45.1(b) and 45.1(c) of the GMCTR – for submitting Form 63 and Form 64 to September 30, 2026, where applicable, for tax years ending between December 31, 2024 and March 31, 2025.