Belgium has updated its minimum tax rules to implement the EU Minimum Taxation Directive, introducing a 15% top-up tax for large multinational and domestic groups. The law mandates digital reporting, clarifies the treatment of joint ventures, requires a single group representative, and strengthens joint liability, while setting clear timelines and rules under the IIR and UTPR to align with international tax standards.
Belgium’s parliament has adopted a bill amending the minimum tax law to implement the EU Minimum Taxation Directive (Directive (EU) 2022/2523). The bill was approved on 18 December 2025 and published in the Official Gazette on 30 December 2025.
The full text of the law, dated 19 December 2025, appears in Official Gazette No. 294 of 31 December 2025.
The legislation introduces a 15% minimum effective tax rate for large multinational and domestic groups with annual consolidated revenues exceeding EUR 750 million, where either the parent company or a subsidiary is located in an EU Member State.
Additionally, it introduces mandatory digital communication via a secure platform for all tax-related notifications and data exchanges. The law also refines specific definitions, notably clarifying the status of joint ventures and their associated entities within a group’s structure. Key definitions, including “group entity” and “reporting group entity,” are revised, and a formal definition of “joint ventures” is introduced. These revisions establish new rules for joint liability among group members concerning top-up taxes and specify the timelines for tax assessments and audits.
Furthermore, the legislation requires groups to appoint a representative entity to manage administrative obligations and legal rights on behalf of all members. These updates ensure that Belgium’s fiscal framework remains aligned with international standards for corporate tax consistency.
The main changes are as follows:
Corporate tax
The key update is the top-up tax system, which ensures that large groups pay at least the minimum tax rate on their profits.
- Domestic top-up tax: Belgian entities belonging to a large group are now clearly subject to a domestic top-up tax if their effective tax rate falls below the minimum requirement. The domestic top-up tax applies if the effective tax rate is below 15%.
- Global rules (IIR and UTPR): The law reinforces the Income Inclusion Rule (IIR), which targets parent companies to ensure their foreign subsidiaries are taxed appropriately. It also clarifies the undertaxed profits rule (UTPR), which acts as a backstop when the main parent company is located in a country that doesn’t apply the minimum tax. The rule applies to Belgian group entities, excluding investment entities, where the MNE group’s ultimate parent is either an excluded entity, located in a third country without a qualified IIR, or established in a jurisdiction deemed low-tax under the law. When multiple group entities are subject to the UTPR, a joint assessment applies.
New rules for joint ventures
One of the key changes in the 2025 update concerns the treatment of joint ventures. The law now introduces a clear definition, classifying a joint venture as an entity in which the parent company holds an interest of at least 50%. If a joint venture is owned 50/50 by two multinational groups, the Belgian domestic top-up tax is split equally between them. This removes previous ambiguity about who is responsible for the bill.
The joint venture rules exclude ultimate parent entities subject to the IIR, exempt entities, entities that mainly hold assets or carry out ancillary activities for excluded entities, entities with largely excluded income, groups composed solely of excluded entities, and certain affiliated parties or permanent establishments linked to joint ventures or to ultimate parent companies.
Digital-first reporting
All tax-related communications, filings, and data exchanges must now be conducted electronically via a secure platform operated by the Federal Public Service Finance. Companies are required to appoint a representative for these digital obligations; if none is designated, the role automatically falls to the Belgian parent company or, failing that, the entity with the largest balance sheet.
Group entities
The rule subjecting all Belgian group entities to the minimum tax will be repealed. Instead, the law clarifies that a joint filing system applies, meaning not every individual group company is required to file separately.
Notifications
All tax-related notifications will be issued electronically via a secure platform operated by the tax administration.
Statute of limitation period
The tax administration has 6 years to conduct audits and establish the tax assessment. This six-year clock begins on January 1st of the year designated as the assessment year (aanslagjaar) for which the tax is due.
This period applies to the inspection and establishment of the domestic top-up tax, the Income Inclusion Rule (IIR) top-up tax, and the Undertaxed Profits Rule (UTPR) top-up tax.
Additionally, the law specifies that, for these assessments, the taxable period is treated as the group’s reporting year. If a reporting year ends on December 31st, the “assessment year” is the following calendar year; if it ends on any other date, the “assessment year” is the year in which that reporting year closes.
Holding structures
Parent entities with direct or indirect stakes in a joint venture or affiliated party must apply the IIR to their share of the additional tax. The joint venture and its affiliates are treated as separate group entities for calculating top-up taxes, with each parent’s share reducing the joint venture’s liability. Any remaining surcharge is added to the total UTPR surcharge.
Tax assessment
Tax assessments must be issued within six months of filing the minimum tax return.
Single general representative for group minimum tax compliance
Under the new Belgian rules, each multinational or large domestic group must operate through a single “general representative” to handle all administrative and legal obligations related to the domestic and UTPR top-up taxes. This representative acts on behalf of all Belgian group entities, providing the tax administration with a single point of contact rather than dealing with multiple entities.
The group may freely designate a Belgian entity as representative via the secure digital platform. If no formal designation is made, the entity that effectively files the tax return or report is deemed the representative.
The representative is responsible for centralised filings and assumes the roles of the filing group entity and the designated local entity. The official language used with the tax authorities is determined by the representative’s place of establishment. Although the representative manages compliance, the tax authorities may still audit individual group entities, and all Belgian entities remain jointly and severally liable for the tax.
Stricter deadlines and liability
The Belgian tax authorities are granted a six-year period to review and assess the tax, starting from the first day of the year in which the tax becomes due. In addition, liability rules are strengthened by introducing joint and several liability among all Belgian group entities, allowing the authorities to recover the full top-up tax from any Belgian entity if another group member fails to pay.
Earlier, Belgium’s Federal Public Service Finance issued Circular 2025/C/68 on 23 October 2025, providing guidance on the minimum tax for multinational and large domestic groups established under the 19 December 2023 law.
