Tax Planning
Tax Planning Strategies in the Age of Global Minimum Tax (GMT) Implementation
With the Global Minimum Tax (GMT) now impacting more jurisdictions, multinational enterprises must adapt their tax planning strategies to align with new top-up tax and safe-harbour provisions.
By NomadicTax Research Team • 5-8 min read • August 12, 2026
## What is the Global Minimum Tax (GMT)?
The GMT, based on the OECD’s GloBE Model Rules under Pillar Two of BEPS, requires **in-scope multinationals** (usually those with revenues over €750 million) to compute their jurisdictional Effective Tax Rate (ETR). If the ETR is **below 15%**, a top-up tax may apply, via the Income Inclusion Rule (IIR) or via Qualified Domestic Minimum Top-up Taxes (QDMTTs). ([oecd.org](https://www.oecd.org/en/topics/global-minimum-tax.html?utm_source=openai))
## Key Developments Affecting Tax Planning (2026)
- In May 2026, implementing jurisdictions agreed to a *common understanding* that the GIR (GloBE Information Return) could be **centrally filed** in one jurisdiction and exchanged, to reduce duplication and avoid penalties where exchange relationships are not fully activated. ([oecd.org](https://www.oecd.org/en/about/news/announcements/2026/05/global-minimum-tax-release-of-a-common-understanding-of-implementing-jurisdictions-and-further-administrative-guidance-to-support-compliance.html?utm_source=openai))
- A **Global Minimum Tax Implementation Toolkit**, released in April 2026, provides guidance for jurisdictions and businesses to implement the GMT efficiently—with modules for timelines, safe-harbours, substance-based incentives, and record keeping. ([oecd.org](https://www.oecd.org/en/publications/the-global-minimum-tax-implementation-toolkit_0ee66d84-en.html?utm_source=openai))
- The **Side-by-Side Package** further simplifies reporting: introduces simplified ETR safe harbour, substance-based tax incentive (SBTI) safe harbour, and rules for when ultimate parent entity (UPE) jurisdictions qualify, reinforcing QDMTTs as primary tools. ([oecd.org](https://www.oecd.org/en/topics/global-minimum-tax.html?utm_source=openai))
## Practical Tax Planning Considerations
| Planning Objective | Considerations & Actions |
|---|---|
| **Maximising ETR to avoid top-up tax** | • Evaluate eligible **tax incentives** under SBTI safe-harbour—ensure expenditure-based incentives have sufficient substance. <br>• Review tax incentive regimes: patent boxes, IP regimes, tax holidays—some may be partially excluded (or limited) under GloBE. |
| **Using QDMTTs strategically** | • A jurisdiction implementing QDMTT can collect top-up locally, reducing exposure to IIR or UTPR in other jurisdictions. <br>• Ensure domestic legislation qualifies; check if transitional status or full qualification has been reached. |
| **Central filing of GIR** | • Identify which jurisdiction will serve as the central filing jurisdiction (often the UPE or Designated Filing Entity). <br>• Understand deadlines and ensure the jurisdiction has an operational portal. <br>• Maintain notifications where required so local jurisdictions accept central filing. |
| **Structuring entity/substance** | • Establish real substance where incentives are claimed: operations, staff, assets. <br>• Document activities clearly to defend against audits. |
## Example Scenario
Consider a multinational group headquartered in Country A (with full IIR rules), with subsidiaries in Country B (low tax + incentive) and Country C (high tax). If Country B has a QDMTT in place that meets qualification, the top-up tax can be collected locally in Country B—meaning the group avoids IIR-based top-up taxation in other jurisdictions. If no QDMTT exists, IIR might apply in Country A or UPE jurisdiction, increasing global tax burden.
## Actionable Steps for Multinationals Now
1. Conduct a **jurisdictional ETR analysis** across operations to identify jurisdictions where ETR <15%.
2. Review local incentive regimes to assess eligibility under SBTI safe harbour.
3. Map out which jurisdictions have implemented QDMTTs or announced qualification—re-structure accordingly.
4. Plan for central filing of the GIR—determine which entity will file, ensure portal access, and coordinate with tax advisors in involved jurisdictions.
5. Update transfer pricing and documentation practices to reflect GMT-related substance expectations.
## Risks if Ignored
- Unexpected top-up tax under IIR or UTPR.
- Loss of benefit from incentives due to non-qualification or inadequate substance.
- Penalties or reputational costs if filing and reporting obligations are not met especially in jurisdictions lagging exchange or portal activation.
**Conclusion**: The GMT is reshaping global tax planning. Businesses that proactively adapt by leveraging safe-harbours, securing qualified domestic regimes, and structuring operations with substance will gain compliance confidence and tax efficiency under the new international tax landscape.