Pillar Two:

Over the past year, multinational enterprise groups have moved from assessing the potential impact of Pillar Two to managing its practical implementation. For many organisations, 2026 marked the first real compliance cycle, including the preparation of Qualified Domestic Minimum Top-up Tax (QDMTT) calculations and the first Global Information Return (GIR) reporting obligations. As those initial filings are being completed, a clearer picture is emerging of the operational, compliance and strategic challenges created by the global minimum tax framework.

Compliance is more than a tax exercise

While much of the early focus was placed on understanding the technical rules, the first compliance cycle has demonstrated that the largest challenge is often operational rather than purely tax related. Many groups have spent significant time gathering data, aligning accounting information across jurisdictions and establishing processes to support reporting requirements. In practice, Pillar Two has become a cross-functional project involving tax, finance, accounting, legal and technology teams.

Key lessons from the first compliance cycle

Simplifications and safe harbours matter

One of the most important developments during 2026 has been the continued focus by the OECD on simplification measures. The OECD's latest simplification package introduced additional safe harbours and practical mechanisms aimed at reducing compliance burdens for eligible multinational groups.

Switzerland has incorporated these developments through its latest administrative guidance, providing taxpayers with greater certainty regarding their application. For many organisations, understanding and appropriately applying these simplifications may become one of the most effective ways to manage future compliance costs and administrative burdens. 

Switzerland has entered the operational phase

The Swiss QDMTT has been in force since 2024, while the Income Inclusion Rule (IIR) has applied since 2025. During 2026, the Swiss Federal Tax Administration continued to issue practical guidance addressing topics such as deferred tax positions, safe harbours and the implementation of the latest OECD developments. The focus has therefore shifted from legislative implementation to practical administration, compliance and the consistent application of increasingly detailed guidance. 

The compliance burden is becoming clearer

Initial discussions surrounding Pillar Two primarily focused on potential top-up tax exposure. Following the first compliance cycle, many groups have discovered that the operational effort required to comply with the rules may be as significant as the tax impact itself. Collecting data, documenting positions, monitoring safe harbour eligibility, preparing reporting obligations and coordinating stakeholders across multiple jurisdictions often require substantial internal resources. As organisations move into subsequent filing cycles, many are evaluating how to streamline compliance processes while maintaining appropriate levels of control and transparency.

Looking beyond compliance

Although the immediate priority has been meeting reporting obligations, multinational groups are increasingly evaluating the broader implications of Pillar Two. Investment decisions, tax incentives, acquisition strategies and legal entity structures may all be affected by the new framework. Groups are beginning to consider whether existing structures remain fit for purpose in a post-Pillar Two environment and how future transactions should be assessed through both a tax and operational lens.

As organisations gain experience with the rules, the discussion is expected to evolve from pure compliance towards strategic decision-making. For tax leaders, finance teams and Boards, the challenge will no longer be limited to understanding the rules, but rather understanding how those rules may influence future business decisions. 

What leading groups are focusing on now

As organisations move beyond their first Pillar Two filing cycle, many are shifting their attention from implementation to optimisation. Key areas of focus include improving data quality, embedding compliance processes into existing reporting frameworks, assessing eligibility for available safe harbours and evaluating the long-term implications of Pillar Two on investment and operating models. For many groups, the next challenge is no longer determining whether they are within scope but ensuring that compliance can be managed efficiently and sustainably over time.

Conclusion

The first compliance cycle has demonstrated that Pillar Two is no longer a future tax reform but an operational reality for many multinational groups. While technical calculations remain important, the key challenges increasingly relate to data management, reporting processes, resource allocation and long-term planning.

As Pillar Two moves beyond its initial implementation phase, the organisations that will derive the greatest benefit from the first compliance cycle are not necessarily those that have simply filed their obligations, but those that have used the process to strengthen data quality, streamline compliance and better integrate tax considerations into broader business decision-making.