Pillar Two and the global minimum tax: a finance guide

The OECD’s Pillar Two framework represents one of the most significant shifts in international tax policy in decades. Designed to ensure that large multinational groups pay a minimum effective tax rate of 15% wherever they operate, the rules are now live in dozens of jurisdictions and the compliance clock is ticking. For finance teams managing multi-entity structures, understanding Pillar Two reporting is no longer optional; it is a core part of the financial close and planning cycle.

This guide walks through the essential mechanics of the GloBE rules: who is in scope, how the minimum tax rate is calculated, what the top-up mechanisms mean in practice, and what finance teams need to do to stay compliant. Whether you are building your first Pillar Two compliance process or refining an existing approach, the sections below provide a clear, practical foundation.

Which companies fall under Pillar Two’s scope

The GloBE rules apply to multinational enterprise groups with annual consolidated revenue of at least €750 million in at least two of the four preceding fiscal years. This threshold mirrors the Country-by-Country reporting threshold, which makes it a familiar benchmark for many finance teams already managing CbCR obligations.

Importantly, the rules focus on the group as a whole rather than individual entities. Even if a specific subsidiary operates in a jurisdiction with a high statutory tax rate, it may still be caught by the rules if the group’s overall structure triggers a top-up liability elsewhere. Purely domestic groups, those operating in a single country, fall outside the scope, as do certain investment funds, pension funds, and government entities, which benefit from specific exclusions under the OECD Pillar Two framework.

How the 15% effective tax rate is calculated

The effective tax rate under Pillar Two is not the same as the statutory rate a company pays in a given country. It is calculated on a jurisdiction-by-jurisdiction basis using a specific formula: covered taxes divided by GloBE income. Both inputs require careful adjustment from standard accounting figures.

GloBE income starts with net financial accounting income and then applies a series of adjustments, removing dividends from qualifying ownership interests, excluding gains on certain equity disposals, and adding back specific expense items. Covered taxes include current and deferred tax charges, but not all deferred tax movements qualify. Timing differences and the treatment of deferred tax liabilities are particularly nuanced areas where errors can distort the effective rate calculation significantly. Finance teams need granular, entity-level data to get this right, which is why automated consolidation and reporting infrastructure matters so much in the Pillar Two context.

Top-up tax mechanisms: IIR, UTPR, and QDMTT explained

When a jurisdiction’s effective tax rate falls below 15%, Pillar Two provides three mechanisms for collecting the shortfall. Understanding which applies in a given situation is central to accurate Pillar Two reporting.

The Income Inclusion Rule (IIR)

The IIR is the primary charging mechanism. It allows the ultimate parent entity’s jurisdiction to impose a top-up tax on low-taxed income earned by subsidiaries in other countries. If the parent jurisdiction has enacted Pillar Two legislation, it collects the difference between the 15% minimum and the actual effective rate in the low-tax jurisdiction.

The Undertaxed Profits Rule (UTPR)

The UTPR acts as a backstop. Where the IIR does not fully capture the top-up tax, for example, because the parent jurisdiction has not yet enacted the rules, the UTPR allows other group jurisdictions to collect the remaining amount. It is allocated among participating jurisdictions based on a formula involving employees and tangible assets.

The Qualified Domestic Minimum Top-Up Tax (QDMTT)

A QDMTT allows a country to impose its own domestic top-up tax before the IIR or UTPR can apply. Many jurisdictions are introducing QDMTTs precisely to retain taxing rights over their own companies rather than ceding them to another country. For groups, a QDMTT in a low-tax jurisdiction can simplify compliance by consolidating the top-up liability locally, but only if that QDMTT meets the OECD’s qualifying conditions.

Safe harbours and transitional relief available to MNEs

Recognising the complexity of the full GloBE calculation, the OECD introduced a set of safe harbours that allow qualifying groups to simplify or defer their compliance obligations during the transitional period.

The transitional Country-by-Country reporting safe harbour is the most widely used. It allows groups to demonstrate that a jurisdiction is not low-taxed using data already collected for CbCR purposes, rather than performing the full GloBE computation. Three tests apply: a de minimis revenue and profit test, a simplified effective tax rate test, and a routine profits test. If a jurisdiction passes any one of these, no top-up tax is due there for that year. This safe harbour is available for fiscal years beginning on or before 31 December 2026, making 2026 a critical year for groups still refining their data processes. Our Country-by-Country reporting module is designed to help finance teams generate and manage exactly the kind of structured CbCR data these safe harbours rely on.

Permanent safe harbours are also being developed, including a simplified calculation approach for jurisdictions with low risk of triggering a top-up liability. These are intended to reduce the compliance burden for groups with straightforward structures in certain markets.

Key compliance and reporting obligations for finance teams

Pillar Two places significant new demands on finance functions. The primary reporting obligation is the GloBE Information Return (GIR), a standardised filing that captures entity-level data on GloBE income, covered taxes, and top-up tax calculations across all jurisdictions. The GIR must generally be filed within 15 months of the fiscal year end, or 18 months for the first year of application.

Beyond the GIR itself, groups need to establish reliable processes for collecting consistent, auditable financial data at the legal entity level. This includes tracking deferred tax positions, monitoring structural changes that affect scope, and documenting the basis for any safe harbour claims. Many finance teams find that their existing ERP and consolidation infrastructure was not built with this level of jurisdictional granularity in mind, which creates real pressure on close timelines and data quality. Platforms like AARO are built to support exactly this kind of structured, multi-entity reporting, helping teams move from fragmented spreadsheets to a controlled, audit-ready environment.

How Pillar Two is reshaping global tax planning strategies

The introduction of a binding global minimum tax rate changes the calculus of international tax planning in fundamental ways. Structures that previously relied on low-tax jurisdictions to reduce the group’s overall effective rate now face a top-up charge that largely neutralises the benefit. This is pushing tax and finance teams to reassess where value is genuinely created within the group rather than where it is most efficiently taxed.

Substance is becoming more important than ever. The GloBE rules include a Substance-Based Income Exclusion (SBIE), which carves out a portion of income based on payroll costs and tangible assets in each jurisdiction. Groups with genuine operational presence in low-tax markets can reduce their top-up exposure through this exclusion, but it requires accurate, jurisdiction-level data on headcount and asset values. At the same time, the QDMTT trend means that even jurisdictions that were previously considered tax-efficient are now collecting tax domestically, shifting the competitive dynamic between locations.

Looking ahead, Pillar Two is also accelerating the convergence of tax and finance functions. The data requirements for GloBE compliance overlap significantly with group consolidation, statutory reporting, and CbCR, which means the teams and systems managing those processes are increasingly central to tax compliance as well. For finance leaders, investing in robust, integrated reporting infrastructure is not just a compliance decision. It is a strategic one that will define how efficiently the group can navigate an increasingly complex global tax environment. Explore how our CbCR and group reporting tools can support that transition.