Key points

  • The September 11 revision adds a mechanism for U.S.-headed groups to elect the side-by-side safe harbour.
  • The updated return covers fiscal years beginning on or after December 31, 2025.
  • Local minimum-tax reporting remains relevant, and a revised electronic filing schema is still being developed.

U.S.-headquartered multinationals have a new reporting mechanism to claim protection from overlapping cross-border minimum taxes after the OECD published a revised GloBE Information Return on September 11. The U.S. Treasury welcomed the revision as an implementation step for the side-by-side arrangement agreed earlier this year, rather than a new domestic tax-rate cut.

The return adds a field for eligible groups to elect that safe harbour and provides associated reporting exemptions, according to Treasury. The protection concerns Pillar Two's Income Inclusion Rule and Undertaxed Profits Rule. It should not be read as a blanket exemption from every tax a U.S. company's overseas subsidiaries may face.

An agreement becomes a reporting process

Treasury linked the change to President Donald Trump's international tax agenda and January's agreement with members of the OECD/G20 Inclusive Framework. Secretary Scott Bessent said the objective was to keep U.S.-headed groups within the American global minimum-tax system without duplicating foreign cross-border charges and compliance obligations. Those are the administration's stated aims; the release does not quantify company-level savings.

The OECD describes the GloBE return as a standardized information package that tax authorities use to check multinational groups' minimum-tax liabilities. Its publication history also matters: the original return appeared in 2023, an updated version followed in January 2025, and September's edition incorporates the January 2026 side-by-side package. The latest publication therefore changes the compliance machinery for an existing framework.

Local taxes remain part of the picture

Treasury says the revised form also standardizes reporting for local minimum taxes and limits distribution of information supplied for those purposes to the relevant jurisdiction. The distinction matters for corporate finance teams: relief from cross-border top-up rules and obligations arising under a country's own minimum tax are separate questions.

Independent specialist publication OECDPillars, which is not affiliated with the OECD, reported that the September package translates January's arrangement into reporting obligations. It also emphasized that international guidance operates through domestic legal systems. Publication alone does not create an identical commencement date in every country, because some jurisdictions need legislation or regulations to give changes effect.

What reporting teams need to track

The OECD specifies that this version of the return is for fiscal years starting on or after December 31, 2025. That is the beginning of the covered financial year, not a universal filing deadline. The organization says a revised XML schema, the electronic structure used to exchange the information, is still being developed.

That pending technical update leaves work for tax authorities and businesses adjusting their data collection and filing systems. For groups operating across several jurisdictions, the practical issue is matching the applicable return, reporting period and local implementation rules. A simplified international form does not by itself establish that every domestic filing obligation has disappeared.

The return's introduction explicitly separates information reporting from declaring and paying tax. It also preserves authorities' ability to request supporting information when checking compliance under domestic law.

Further implementation is still ahead

The wider September package introduces a framework for detailed peer reviews of national minimum-tax legislation, with recommendations where inconsistencies are found. It also addresses certain conditional taxes and mismatched accounting periods. The OECD plans further guidance on discriminatory tax features by year-end, so the reporting revision is one stage in an implementation process that remains unfinished.

Sources

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