Upcoming deadlines in global minimum taxation

By February 28, 2026, the domestic subsidiaries of the affected multinational corporations must declare whether they are subject to the GloBE additional tax on a separate form, and they must also present the multinational or large domestic group of companies to which they belong. The deadline for this report will now be the last day of the second month of the year following the tax year (for 2024, this had to be reported by the end of the given year), i.e. for calendar taxpayers, it is February 28, 2026 for 2025.

At the same time, two other obligations in the global minimum tax will also arrive in June 2026 – sooner than we might think. The QDMTT (Qualified Domestic Minimum Top-up Tax) return (in which the new regulation on exemptions must be applied) and the GloBE Information Return (GIR) report must be submitted for the first time on June 30, 2026, which present the tax data of the members of the corporate group in detail and the taxes actually paid by country. This shows in which country the corporate group may be under-taxed and to which country(ies) the tax difference compared to the internationally expected 15% effective tax must be paid. These tasks are so complex that they can pose a great challenge for companies’ finance and tax departments – not only in terms of accurate data collection and calculations, but also in terms of harmonizing the rules of different countries – so even though the deadline seems distant, it doesn’t hurt to start preparing now!

Especially since the two global minimum tax regulations were announced in the last days of 2025, followed by a third regulation at the end of January 2026 – not at all simplifying legal compliance. One regulation defines the concepts and implementation rules related to individual exemptions and the detailed calculation method of exemptions (Regulation 38/2025 of the Ministry of Finance), the other defines GloBE data provision, GIR data content and GloBE data exchange (Regulation 46/2025 of the Ministry of Finance). The third summarizes the detailed rules for domestic notification, return and tax payment (Regulation 4/2026 of the Ministry of Finance).

In this still rather flexible legal environment, fraught with new challenges, preparation should not be postponed; implementation must begin by interpreting the already known rules, involving consultants in case of questions or uncertainties, allocating tasks within the company group, and collecting data.