As the first Pillar Two deadlines approach, one observation keeps coming up across organisations: understanding the rules is no longer enough. The real challenge now lies in implementation.

Because behind the principle of a 15% global minimum tax rate, the operational reality is far more demanding. Groups must deal with fragmented data, shifting scopes, and calculation frameworks that sit at the intersection of tax and financial consolidation.

The result? Many organisations are realising (sometimes too late), that their level of readiness was overestimated.

Less a tax topic, more an operational one

On paper, Pillar Two may look like just another tax regulation. In practice, it quickly becomes a cross-functional project that extends far beyond the tax department.

The required data doesn’t come from a single system. It spans consolidation tools, Country-by-Country Reporting (CbCR), and often additional fragmented sources. Its interpretation relies on specific rules, and its use requires close coordination between teams that are not used to working together.

This is exactly where the first challenges emerge.

The scope trap

At first glance, defining the Pillar Two scope may seem straightforward. In reality, it rarely is.

Many groups assume their Pillar Two scope aligns with their consolidation perimeter or their CbCR reporting. In practice, discrepancies are common. Some entities need to be added, others excluded, and aggregation rules do not always match existing practices.

This gap is often underestimated – yet it can undermine the entire process. Because once the scope is misdefined, all subsequent calculations are built on unstable foundations.

A data issue before a calculation issue

Another key takeaway from the field: the data often exists – but it is not readily usable.

Critical elements such as deferred tax bases or inputs required for GloBE calculations may be scattered, incomplete, or difficult to extract. Reconstructing them takes time and introduces additional risk within already tight timelines.

This is often the moment when Pillar Two shifts from a theoretical topic to a real operational challenge.

Safe harbours: a shortcut… with conditions

Given the time pressure, simplification mechanisms (particularly transitional safe harbours), can seem like an obvious solution. In theory, they allow companies to reduce the scope of calculations and move faster.

But only if the prerequisites are met.

An incomplete CbCR or poorly structured data can quickly invalidate their use. What was meant to be a shortcut can turn into an additional layer of complexity.

The final mile: reporting

This is often the blind spot in many projects.

Once calculations are completed, companies still need to prepare and submit the Global Information Return (GIR), based on structured reporting requirements defined at OECD level. While it may appear as a technical step, it actually concentrates a significant portion of the risk.

Requirements are extensive, controls are strict, and feedback from tax authorities may come months after submission.

In other words, errors are not always immediate – they can surface much later, when teams are already focused on the next reporting cycle.

A regulation that is here to stay

Pillar Two is not a one-off project. It is a long-term framework, with ongoing developments and more to come.

Its implications go beyond compliance. They affect data governance, process structuring, and in some cases, broader strategic decisions. This is why purely declarative approaches quickly reach their limits.

The challenge is no longer just about filing a report, it’s about building a sustainable and scalable framework.

Access the full webinar replay

What our webinar shows in practice

To address these challenges, kShuttle and Satriun hosted a webinar built around a simple question:

Are you really ready for Pillar Two?

In this replay, you will see:

• how to quickly identify risk areas
• the most common mistakes when defining scope
• how to use safe harbours effectively
• what XML generation actually changes
• and why “quick-fix” approaches often fall short

All illustrated with a practical demonstration of calculation and reporting logic.