KPMG tax teams rely on OECD Pillar Two as global minimum tax rules evolve

In January 2026, KPMG was already tracking an 88-page OECD Side-by-Side Package modifying key parts of Pillar Two. It is the framework KPMG teams keep returning to when clients ask what data they need, where top-up tax might land, and which assumptions will hold up when local filing rules start to bite.

The rules behind the client question

The OECD built the modern Pillar Two framework on the Global Anti-Base Erosion, or GloBE, Model Rules. The point is straightforward even if the mechanics are not: large multinational enterprises should pay at least a minimum level of tax in each jurisdiction where they operate. That architecture is what gives the regime its practical force for KPMG professionals, because every local return format, safe-harbor test, or implementation tweak has to fit back into the same global model.

That global model emerged from a longer reform effort. The BEPS project began in 2013 after concerns that the international tax system had failed to keep pace with the modern global economy, and the 2015 BEPS package contained 15 actions aimed at countering tax avoidance. Pillar Two is the part of that agenda that turned into a minimum-tax floor, with the OECD/G20 Inclusive Framework agreeing the rules in October 2021.

Why the timeline still matters in day-to-day work

The sequence from agreement to guidance is one reason the topic keeps generating work inside KPMG. The OECD published the Pillar Two model rules in December 2021, followed by commentary in March 2022 and further administrative guidance in February 2023. The headline rule set may be stable, but the administrative layer keeps changing the questions client teams have to answer.

In October 2021, more than 135 jurisdictions joined the plan, and the Inclusive Framework statement had grown to 139 member jurisdictions by 9 June 2023. Pillar Two is not a niche tax model for a handful of markets. It is a multi-jurisdiction compliance system that can affect reporting packages, entity mapping, deferred tax calculations and the way global teams coordinate close calendars.

Where the real scoping mistakes happen

For KPMG teams, the most common mistake is treating Pillar Two as if it were only about top-up tax. It is about top-up tax, but the first real work starts earlier, with effective tax rate calculations, jurisdiction-by-jurisdiction data gathering and the assumptions that drive whether a group falls inside a safe harbor. If a team scopes the project as a narrow tax computation exercise, the client ends up with the wrong data request list and an underbuilt timeline.

That is where the framework’s global logic becomes operational. The minimum tax is designed to reduce the incentive for profit shifting and put a floor under tax competition. A KPMG professional translating that into client work has to ask where the group books income, which entities carry substance, how the effective tax rate is modeled, and which local filings can be standardized without losing accuracy. The answer often determines whether the first deliverable is a light-touch assessment or a much deeper data and controls review.

Safe-harbor assumptions are especially easy to mishandle. If a team assumes a safe harbor will apply everywhere, it can miss the differences between jurisdictions that have adopted the rules at different speeds or with different administrative overlays. If it assumes nothing qualifies, it can overstate exposure and set client expectations too high, forcing unnecessary work and unnecessary anxiety during already compressed reporting cycles.

Why incentives, deal work and transfer pricing are still in play

Pillar Two has moved far beyond the tax provision. The 15% global minimum tax has important implications for tax incentives worldwide, and countries have been reforming or reconsidering incentive regimes between 2022 and 2025 because of it. That means clients are not just asking how much tax they owe. They are asking whether an incentive still works, whether it creates a top-up tax leak, and whether it changes the economics of a planned investment.

The knock-on effects reach into deal structuring, transfer pricing, deferred tax and post-close planning. A group that acquires a business with multiple low-taxed jurisdictions cannot treat Pillar Two as a year-end footnote. It has to model the effective tax rate on a forward basis, understand how carve-out assumptions affect exposure, and decide whether local incentives, credits or elections still deliver value once the 15% floor is applied.

What the newest guidance changes

The rule set did not stop moving after the initial model rules. That January 2026 OECD Side-by-Side Package followed an OECD agreement in December 2025 and a webinar the next month on how the global minimum tax works in coordinated operation.

The administrative side is changing too. In May 2026, jurisdictions implementing the global minimum tax from 2024 agreed a common understanding to preserve the administrative and compliance benefits of central filing for the GloBE Information Return. Central filing can reduce duplication across jurisdictions, but only if teams understand which data points travel cleanly and which still need local tailoring.

In September 2024, the OECD advanced the Pillar Two Subject to Tax Rule through a treaty announcement, a move especially relevant for protecting developing-country tax bases. For multinational clients, that adds another layer of analysis on top of the core effective tax rate work, particularly where treaty positions, local withholding taxes and incentive structures overlap.

What KPMG professionals need to explain plainly

The best client conversations do not start with the number 15. They start with the operating model. If a group has a few heavily incentivized jurisdictions, thin documentation on substance, or fragmented data ownership across finance and tax, Pillar Two will show up as a coordination problem before it shows up as a tax calculation.

The OECD’s Implementation Toolkit draws on jurisdictions furthest along in implementation, plus input from business and wider stakeholder groups, to identify best practices for consistent and efficient administration. For KPMG teams, the practical lesson is to build a request list that matches the model rules, explain where the data will come from, and separate genuine exposure from assumptions that only work on paper.