OECD releases new Global Minimum Tax implementation package

On 11 September 2026, the OECD/G20 Inclusive Framework released three important components of the continuing implementation architecture for the Global Minimum Tax.

These include a framework for reviewing domestic legislation implementing the Global Minimum Tax, revisions to the GloBE Information Return, and further Administrative Guidance concerning application of the GloBE Model Rules.

The revised GIR incorporates changes arising from the January 2026 Side-by-Side package.

The OECD states that these revisions apply to GIRs for fiscal years commencing on or after 31 December 2025.

Pillar Two is increasingly not merely a tax-calculation exercise.

It creates a substantial data, systems, reporting and jurisdictional-coordination exercise for affected multinational groups.

The legislative-review framework is also significant because the Inclusive Framework will assess whether jurisdictions' domestic implementation is consistent with the GloBE Model Rules and Commentary.

For affected multinational groups, existing Pillar Two implementation models should not be treated as static.

Finance and tax teams may need to determine whether their data architecture can support the revised GIR, whether existing calculations capture the latest guidance, and whether local implementation across relevant jurisdictions creates differences requiring further analysis.

Groups within the Global Minimum Tax framework should consider reviewing:

GloBE reporting data → entity and jurisdiction mapping → local accounting information → tax attributes → reporting systems → internal controls → filing responsibilities across jurisdictions.

The objective is not simply to calculate a number, but to ensure that the information supporting that number can move consistently through the group's reporting architecture.

Global Minimum Tax compliance increasingly sits at the intersection of international tax, accounting, data and reporting.

Groups that treat Pillar Two only as a year-end tax computation may discover that the greater challenge is obtaining consistent information across entities and jurisdictions.