20 November 2026 marks another important tax compliance deadline for groups within the scope of the global minimum tax rules. By this date, affected Hungarian constituent entities must file their Qualified Domestic Minimum Top-up Tax (QDMTT) advance payment returns for the 2025 fiscal year and pay any tax advance due.
However, compliance involves more than simply submitting a tax return. Companies must also substantiate their eligibility for applicable exemptions and safe harbours, assess the tax position of their Hungarian constituent entities, and ensure that the underlying calculations are properly supported.
Experience from the first year of implementation suggests that these requirements can be particularly challenging for Hungarian subsidiaries of multinational groups where GloBE calculations are prepared centrally by a foreign parent company.
Global Minimum Tax: A 15% Minimum Rate Does Not Automatically Mean an Additional 6% Tax
The global minimum tax framework, commonly referred to as GloBE or Pillar Two, aims to ensure that multinational enterprise (MNE) groups and large domestic groups within its scope are subject to an effective tax rate of at least 15% in each jurisdiction in which they operate. The rules are designed to reduce tax advantages arising from differences in corporate tax rates across jurisdictions.
As a general rule, the framework applies to MNE groups and large domestic groups whose annual consolidated revenue reaches or exceeds EUR 750 million in at least two of the four fiscal years preceding the year under review.
Importantly, the revenue threshold is not determined solely by reference to net sales revenue. Instead, the relevant revenue reported in the group's consolidated financial statements must be considered.
The rules are also not limited to groups operating across multiple jurisdictions. Large groups operating exclusively in Hungary may fall within their scope if the relevant conditions are met.
The introduction of Pillar Two has attracted particular attention in Hungary, where the statutory corporate income tax rate is 9% (a legislative proposal included in the autumn 2026 tax package could, however, increase the rate to 15% for large companies). Nevertheless, the current 9% statutory rate does not automatically translate into an additional 6% top-up tax liability.
This is because the calculation of the GloBE effective tax rate (ETR) differs significantly from the calculation of conventional corporate income tax. Furthermore, the GloBE tax position is generally determined on a jurisdictional basis rather than separately for each legal entity, taking into account the relevant financial and tax information of the constituent entities operating in the same jurisdiction.
Hungary's 9% corporate income tax rate cannot, in itself, be used to determine whether a global minimum tax liability arises. A properly prepared calculation may demonstrate that the Hungarian constituent entities have no additional top-up tax to pay. However, reaching this conclusion requires a detailed assessment of the overall Hungarian tax position and the available exemptions and safe harbours,” explains Dr Viktória Clamba, Tax Expert at RSM.
20 November: What Are the Key Compliance Obligations?
For groups with a calendar-year consolidated reporting period, the relevant Hungarian constituent entities must file their QDMTT advance payment returns for the 2025 fiscal year and pay any tax advance due by 20 November 2026.
For groups with a non-calendar fiscal year, the deadline falls on the 20th day of the eleventh month following the end of the relevant fiscal year.
The filing must be completed using Form 25GLBADO, published by the Hungarian National Tax and Customs Administration (NAV) in October 2026. The form is available through NAV's Online Form Completion Application (ONYA). NAV's official guidance also confirms the filing deadline and the availability of the form.
A key feature of the QDMTT advance payment regime is that the advance payment is linked to the domestic top-up tax liability determined for the relevant fiscal year. Preparing the return therefore requires substantive GloBE assessments and appropriately supported tax calculations.
This represents an important difference compared with the conventional corporate income tax advance payment system. Rather than relying on a prior year's tax liability, companies must assess actual financial and tax data for the 2025 fiscal year, relevant adjustments and the availability of applicable exemptions and safe harbours.
Ahead of the deadline, companies should therefore confirm that the necessary group-level information is available, the relevant safe harbour assessments and QDMTT calculations have been completed, and responsibility for the Hungarian filing has been clearly assigned.
No Top-up Tax Payable? Filing and Documentation Obligations May Still Apply
A common misconception is that where a group has no actual top-up tax liability, no further action is required. In practice, however, a nil top-up tax liability does not necessarily eliminate filing or documentation requirements.
There are several reasons why the top-up tax payable may be zero. For example, the ETR calculated for the Hungarian constituent entities may reach or exceed 15%, or the group may qualify for an applicable exemption or safe harbour that reduces its top-up tax liability to zero.
Különösen fontosak az országonkénti jelentésen (Country-by-Country Reporting, CbCR) alapuló Safe Harbour szabályok. Az átmeneti CbCR Safe Harbour keretében – a vonatkozó feltételek mellett – három alternatív teszt vizsgálható: a de minimis teszt, az egyszerűsített effektív adókulcs teszt és a rutinprofit-teszt. Ha az adott joghatóságban valamelyik feltétel teljesül, az jelentős könnyítést biztosíthat a kiegészítő adó meghatározásában.
Of particular importance are the safe harbour provisions based on Country-by-Country Reporting (transitional CbCR Safe Harbour). However, eligibility for these reliefs cannot be assumed. Companies must assess the reliability and suitability of the underlying data, the correct determination of the relevant indicators and whether all applicable conditions have been met. Safe harbour eligibility must also be assessed for each fiscal year. In addition, decisions made in previous years may affect the availability of the Transitional CbCR Safe Harbour in subsequent periods. Under the “once out, always out” rule, failing to qualify for or apply the Transitional CbCR Safe Harbour in an earlier year may restrict the group's ability to benefit from it in later years.
Based on our experience, for many companies within the scope of the global minimum tax rules, the greatest challenge is not necessarily paying the tax, but adequately documenting why an exemption or safe harbour applies. Even where no tax is payable, detailed calculations, data reconciliations and robust supporting documentation may be essential to demonstrate that the approach adopted is defensible in a subsequent tax authority audit,” highlights Dr Viktória Clamba, Tax Expert at RSM.
Lessons from the First Year: Group-Level Calculations May Not Be Sufficient for Hungarian Compliance
Experience from the first QDMTT advance payment filing period in 2025 indicates that one of the greatest challenges associated with global minimum tax compliance is not necessarily completing the return itself, but obtaining and validating the underlying data and calculations.
For many multinational groups, GloBE calculations are prepared centrally at parent-company level. This can be an efficient approach, promoting consistency in methodology and reducing the administrative burden on local finance teams. However, centralized calculations may also have limitations. Calculations and assessments prepared outside Hungary do not always fully reflect the specific requirements of Hungarian tax legislation, the treatment of local taxes or the information required in the Hungarian tax return.
Additional difficulties may arise where a Hungarian subsidiary receives only a consolidated result or a brief conclusion from its parent company, without access to the detailed calculations or documentation supporting the application of exemptions and safe harbours. Simply adopting the outcome of group-level calculations may not always be sufficient to meet Hungarian filing obligations. It may also be necessary to verify whether the calculations comply with the Hungarian QDMTT rules and whether the information reported in the local return can be adequately substantiated.
Our experience from the first year shows that centrally prepared GloBE calculations can provide substantial support to Hungarian subsidiaries, but they do not automatically replace a review against local Hungarian requirements. The greatest risks may arise where a local entity has received the final result from its parent company but cannot adequately substantiate the underlying calculations or the legal basis for applying an exemption or safe harbour. Insufficient documentation can become a particular concern during a subsequent tax authority audit,” warns Dr Viktória Clamba, Tax Expert at RSM.
Global Minimum Tax Compliance Does Not End on 20 November
The November advance payment filing is only one of the annual global minimum tax compliance obligations that calendar-year taxpayers must still address in 2026. Constituent entities may also need to prepare for additional filing, notification and information-reporting requirements.
Particular attention should be paid to the GloBE Information Return (GIR), which provides detailed information relating to the group's global minimum tax position. For calendar-year groups, the general deadline for filing the first GIR, relating to the 2024 fiscal year, was 30 June 2026.
Where the GIR is filed by a foreign constituent entity of the group, Hungarian entities must assess whether they qualify for an exemption from the domestic GIR filing requirement. The mere fact that a GIR has been submitted in another jurisdiction is not sufficient in itself. Companies must also verify that the relevant international exchange-of-information conditions are satisfied and that the filing appropriately covers the Hungarian constituent entities.
Where these conditions are met, the Hungarian constituent entities are not required to submit a separate GIR by 30 June. Instead, they must notify the Hungarian tax authority by 31 December 2026, providing information on the jurisdiction and the entity that took care of filing the GIR on behalf of the relevant Hungarian constituent entities.
How Can Companies Prepare for the 20 November Deadline?
With the deadline approaching, affected companies should undertake a targeted review of their global minimum tax position for the 2025 fiscal year. The first step is to confirm that all relevant group-level and Hungarian entity-level information is complete and available. Companies should also consider whether changes in the group structure or tax circumstances could affect the GloBE status of the Hungarian constituent entities.
The next steps should include assessing eligibility for applicable exemptions and safe harbours, preparing or reviewing the QDMTT calculations, and compiling the documentation needed to support the tax return. Timely coordination with the foreign parent company is particularly important. Where the necessary information or calculations have not yet been provided, Hungarian subsidiaries should request them as soon as possible and review them against local compliance requirements. Adequate preparation not only supports timely filing but may also reduce the risk of subsequent corrections, disputes with the tax authorities and potential penalties.
Global minimum tax compliance should no longer be treated as a once-a-year tax exercise. Companies are best positioned to meet their obligations where group-level data collection, local Hungarian tax reviews and supporting documentation form part of an ongoing, coordinated process. Preparing for the 20 November deadline is therefore also an opportunity to strengthen compliance processes for the years ahead,” concludes Dr Viktória Clamba, Tax Expert at RSM.
How Can RSM Support Your Global Minimum Tax Compliance?
The global minimum tax framework presents companies with complex tax, accounting and international coordination challenges. RSM's tax professionals can provide support throughout the compliance process, including assessing whether a group falls within the scope of the rules, evaluating eligibility for safe harbour reliefs, preparing and reviewing GloBE and QDMTT calculations, and assisting with the preparation of related tax returns and information filings.
Our specialists can provide particular value where Hungarian subsidiaries need to reconcile calculations prepared by foreign parent companies with local tax obligations, or where the application of a particular exemption or safe harbour requires further technical analysis.
The objective is not simply to submit a return on time. It is to establish a transparent, well-documented and sustainable compliance process that supports accurate tax reporting while minimising unnecessary administrative burdens.
With the 20 November 2026 deadline approaching, now is the time to review your group's 2025 global minimum tax position.
RSM's tax advisors are available to assist with QDMTT advance payment filings, reviewing exemptions, safe harbour eligibility and underlying calculations, and managing ongoing global minimum tax compliance obligations.
