Top-up taxes are a tool that ensures that large multinational companies pay a minimum effective tax rate of 15% in each country where they operate. Companies from groups of companies with a consolidated turnover of more than CZK 750 million per year are subject to top-up tax obligations. The effective tax rate is calculated on the basis of consolidated financial statements. Both current and deferred taxes are included in the calculation. However, all parameters of the top-up tax need to be adjusted, which presents a number of challenges. For Czech companies that are part of such international or domestic groups, this means the need for deeper cooperation with the parent company, unification of data sources and the search for new data points and flows in order to be able to meet the requirements of this legislation. We have written in more detail about adjustment taxes, for example, here: Adjustment tax: new obligations for multinational groups.
Key changes for clients
A fundamental and highly anticipated change is the extension of the deadlines for filing information reports and tax returns. The deadlines for filing Czech and assigned adjustment taxes have thus been unified. Information reports will be filed within 15 months after the end of the reporting period. For the first, so-called initial, period, this deadline is extended to 18 months. The tax administration will therefore expect the first information reports by 30 June 2026 for the reporting period, which was the calendar year 2024. For those taxpayers who have a reporting period other than the calendar year, the deadlines will run from the end of the reporting period that began after 1 January 2024.
The deadline for filing tax returns for both Czech and assigned adjustment tax is again 22 months after the end of the reporting period. For the calendar year, which is the first year for which adjustment taxes will be calculated and paid, it is therefore necessary to file a tax return by the end of October 2026.
The amendment also provides further clarification of terms and exceptions, including the definition of the reporting period, clarification of tax benefits, and also modifies the decision-making system, which for the purposes of equalisation taxes is primarily the highest parent entity. It further specifies the rules for currency conversion, and the safe harbour rules have also undergone changes.
First filing for adjustment taxes
In June 2025, the Ministry of Finance published a draft decree on tax return forms and information overviews for both Czech and assigned adjustment taxes. While the tax return will have three parts – for Czech equalisation tax, for allocated equalisation tax and a common section – the information overview will be used for both equalisation taxes. All these submissions will be accepted by the tax administration exclusively in electronic form in xml format.
The Czech tax administration has confirmed that it intends to accept the information overview submitted by the highest parent entity also for Czech equalisation tax, provided that it contains all the information necessary for the administration of equalisation tax. Within the European Union, these reports should be exchanged automatically between tax authorities in the EU on the basis of DAC 9. Unfortunately, its implementation into Czech law has not yet been approved.
The tax administration has also announced that it does not currently plan to prepare an interactive form for completing the information report; only its content structure should be published. It will therefore be entirely up to taxpayers to find their own technical solution for creating the information report in XML format. If taxpayers are unable to use the information overview prepared by the highest parent entity (e.g. because the parent company will not prepare such an information overview or will not exchange information with the Czech tax administration, or because the information overview will not contain all the necessary data), taxpayers will have to prepare this overview themselves, including the technical aspects.
The Chamber of Tax Advisers drew attention to this fact in its comments. We can only hope that the tax administration will reconsider this approach and provide a uniform tool for creating a standardised information report, e.g. on its tax portal.