Belgian currency conversion rules for global minimum tax

The Belgian tax authorities have issued guidance on currency conversion for Belgian global minimum tax (GMT – Pillar Two) purposes, based on the OECD Consolidated Commentary published in May 2025. The rules are set out in Circular 2026/C/41 (NL / FR), which is an addendum to Circular 2025/C/68 on the introduction of a minimum tax for multinational enterprises and large domestic groups (see our previous news item: Circular on the implementation of minimum taxation - KPMG Belgium).

This addendum clarifies the rules for converting amounts into euros when they are reported in another currency in the consolidated financial statements and when the top-up tax is calculated in a currency other than the euro. Compared with the OECD rules, the most important clarification is that, for Belgium, the top‑up tax in the presentation currency must be converted using the exchange rate on the last day of the fiscal year, based on the European Central Bank (ECB) reference rate. The rules, as described in the circular, are summarised below.

1. Use of presentation currency

• Multinational enterprise (MNE) groups must perform all minimum tax calculations for each jurisdiction in the presentation currency of their consolidated financial statements, regardless of the local currency of the jurisdiction.
• Many relevant figures will already have been converted into the presentation currency under the applicable accounting standard. Any remaining figures must be converted specifically for the minimum tax calculation, using the same accounting standard’s conversion rules (e.g. IAS 21, ASC 830), even if those conversions are not required for accounting purposes.

2. Conversion of top-up tax into local currency

• Once the amount of the top-up tax has been determined in the presentation currency, it must be converted to the local currency of the jurisdiction where the top-up tax is due. For Belgium, this conversion must be performed using the exchange rate on the last day of the fiscal year, based on the ECB reference rate. This applies to all types of top-up tax (domestic top-up tax, IIR top-up tax and UTPR top-up tax).

3. Monetary thresholds

• Where an MNE group prepares its consolidated accounts in a currency different from that used in national law, it must convert the results of those accounts to determine whether and how it is subject to minimum tax in a given jurisdiction. This conversion can only be done at the end of the fiscal year.
• To reduce uncertainty and ensure consistent application, the group must convert the relevant thresholds from its presentation currency into the currency used in the national law using the same average exchange rate for December of the calendar year preceding the start of the fiscal year concerned. For this purpose:
  • If the domestic threshold is expressed in euro: the ECB reference rates must be used. If the ECB does not publish a rate for the local currency, the central bank rate of the implementing jurisdiction must be used.
  • If the domestic threshold is expressed in a non‑euro currency: the central bank rate of the implementing jurisdiction must be used.
• Where a threshold refers to prior fiscal years (e.g. the EUR 750 million revenue test that must be met in at least two of the four years preceding the tested year), the conversion is done separately for each year.
• The conversion method may lead to results that appear counter‑intuitive for some MNE groups, but this is accepted in order to ensure consistent application of monetary thresholds across all implementing jurisdictions and to provide legal certainty to both taxpayers and tax administrations.

KPMG can assist you with all compliance aspects of the global minimum tax in Belgium and globally, including registration, calculation of tax liabilities, and filing of the required returns. In addition, we can help you identify the relevant data points, collect the necessary data, and perform the calculations for all types of top-up tax.

If you have any questions regarding the applicable rules and their implications for your business, or if you require assistance with the Belgian minimum tax, please do not hesitate to contact your trusted KPMG advisor or reach out to us directly.