Pillar Two GloBE: The UK CFO Compliance Deadline You Cannot Miss

UK multinationals must file the OECD Pillar Two GloBE Information Return by 30 June 2026 or face penalties for non-compliance.

Under the OECD’s Global Anti-Base Erosion (GloBE) Rules — implemented in the UK as the Multinational Top-up Tax (MTT) and the Domestic Top-up Tax (DTT) from 31 December 2023 — large multinationals with annual consolidated global revenues of at least €750 million must pay a minimum effective tax rate (ETR) of 15% in every jurisdiction where they operate. The GloBE Information Return (GIR) is the primary compliance filing that proves this has been achieved. For calendar-year taxpayers, the first GIR filing deadline is 30 June 2026 — a date that is now imminent. For UK CFOs who have not yet completed their GIR readiness assessment, the window is closing.

What Is the GloBE Information Return and Who Must File?

The GloBE Information Return is a comprehensive disclosure submitted to the tax authority of the Ultimate Parent Entity (UPE), which then exchanges it with other jurisdictions under the OECD framework. It documents, for every jurisdiction in which the multinational operates, the ETR calculation, qualifying income, covered taxes, and any top-up tax liability.

The GIR demands over 100 complex data points, many of which are not captured by existing ERP or tax provision systems. This is not a marginal compliance exercise — it represents a fundamental expansion of tax data obligations. According to KPMG’s Pillar Two readiness tracker, fewer than 40% of in-scope multinationals had fully operationalised their GIR data collection process by the start of 2026.

UK in-scope groups must file the GIR with HMRC. HMRC has introduced a UK domestic filing portal, and UK-headquartered groups are the UPE filer. Where a UK entity is part of a non-UK-headquartered group, the UK entity must confirm that a qualifying GIR has been filed in the UPE jurisdiction and provide HMRC with a local notification within the prescribed window.

Executive Action

• Confirm whether your group meets the €750 million revenue threshold — if so, a GIR filing obligation exists.
• Identify whether your entity is the UPE filer or a local notification entity, and confirm your HMRC filing obligations immediately.
• Engage your tax adviser now if GIR readiness has not been formally assessed — the 30 June 2026 deadline for calendar-year groups is upon us.

What Operational Challenges Does Pillar Two Create for UK CFOs?

The GIR’s data demands expose a structural gap in most corporate finance functions. The filing requires jurisdiction-level ETR calculations that combine financial accounting data (IFRS or GAAP profit) with adjusted covered tax figures that differ from both statutory tax accounts and existing tax provision workings. The result: CFOs cannot simply hand Pillar Two to the tax team and walk away. It requires finance function transformation.

Key data challenges include obtaining timely, jurisdiction-level financial data from overseas subsidiaries; calculating Substance-Based Income Exclusions (SBIEs) for payroll and tangible assets in each territory; and applying Transitional Safe Harbours correctly to defer top-up tax obligations. The January 2026 OECD Side-by-Side Package introduced further administrative guidance that modifies key calculation mechanics — CFOs must ensure their advisers are working from the updated rules.

For groups operating across 20 or more jurisdictions, manual processes are not viable. Leading CFOs are investing in dedicated Pillar Two technology platforms — tools from providers such as Corptax, OneSource, and Bloomberg Tax — that automate the data aggregation and ETR calculation process. According to Deloitte’s 2026 Pillar Two survey, 62% of large multinationals have already adopted or are implementing dedicated Pillar Two software.

Executive Action

• Map the data requirements against your current ERP and tax provision systems — identify gaps before attempting a GIR dry run.
• Assess whether manual processes are sufficient for your jurisdictional footprint; consider specialist Pillar Two technology if operating in 10+ jurisdictions.
• Ensure your tax team has reviewed the January 2026 OECD Side-by-Side Package and updated calculations accordingly.

How Should UK CFOs Structure Their Pillar Two Compliance Programme?

Pillar Two is not a one-time filing exercise — it is a permanent addition to the annual compliance calendar, requiring ongoing data governance, system maintenance, and regulatory monitoring. CFOs who treat the first GIR as a project rather than a process will struggle in subsequent years as OECD guidance continues to evolve and top-up tax liabilities crystallise.

A robust Pillar Two compliance programme has five components: data governance (ensuring jurisdiction-level financials are available on a timely basis); ETR modelling (running provisional calculations throughout the year to identify jurisdictions approaching the 15% threshold); Safe Harbour monitoring (tracking whether Transitional CbCR Safe Harbour conditions remain met); GIR preparation (a structured process for assembling the 100+ data points); and board reporting (quarterly updates to the Audit Committee on Pillar Two exposure and filing status).

The board dimension is critical. Under the UK Corporate Governance Code, the board is responsible for the integrity of financial reporting. Pillar Two creates a new category of financial statement risk — deferred tax asset and liability positions will change materially as ETR calculations are finalised. CFOs must brief Audit Committees on the Pillar Two impact on effective tax rate, cash tax payments, and financial statement disclosures. Use the INFORMD capital approval assessment template to structure your Audit Committee briefing materials.

Executive Action

• Establish a standing Pillar Two working group with representation from tax, finance, legal, and treasury — this is a permanent compliance function, not a project.
• Brief the Audit Committee on Pillar Two exposure, GIR filing status, and financial statement impact at every quarterly meeting.
• Build Pillar Two monitoring into the annual finance calendar alongside existing tax compliance milestones.

What Are the Penalties for Pillar Two Non-Compliance?

The penalties for failing to file a compliant GIR or for underpaying top-up tax are material. Under the UK’s MTT legislation, HMRC can impose penalties for late or inaccurate GIR filings, with senior accounting officer (SAO) obligations applying to the CFO personally. Where a group fails to pay the correct top-up tax, interest and penalties accrue in the standard HMRC manner.

In EU jurisdictions, enforcement is more aggressive: fines for serious Pillar Two breaches reach €10 million per jurisdiction, with individual senior managers facing personal liability in some member states. UK companies with EU subsidiaries are subject to both HMRC and local EU enforcement, creating a multi-jurisdictional penalty exposure that compounds rapidly for large groups.

The reputational dimension is equally significant. Pillar Two disclosures are public for listed companies — ETR data, jurisdiction-level tax payments, and top-up tax liabilities are visible to investors, media, and civil society. CFOs who cannot explain their Pillar Two position coherently face investor relations risk as well as regulatory risk. Access the INFORMD financial leadership briefing library for further guidance on managing CFO regulatory risk in 2026.

Executive Action

• Review your group’s SAO obligations in the context of Pillar Two — the CFO’s personal certification now extends to GIR accuracy.
• Identify all jurisdictions where EU-level penalties apply and ensure local compliance leads are briefed on GIR filing obligations.
• Prepare investor-facing Pillar Two disclosure language for inclusion in the next annual report — do not leave this to last-minute drafting.

Frequently Asked Questions

What is OECD Pillar Two?

OECD Pillar Two is a global minimum tax framework that requires large multinationals (€750M+ revenues) to pay a minimum 15% effective tax rate in every jurisdiction. It is implemented via the GloBE Rules, which the UK has enacted as the Multinational Top-up Tax and Domestic Top-up Tax from 31 December 2023.

Which UK companies are in scope for Pillar Two?

UK companies that are part of multinational groups with annual consolidated global revenues of at least €750 million in at least two of the last four fiscal years are in scope. This covers most FTSE 100 companies and a significant number of large FTSE 250 and private groups with substantial international operations.

What is the GloBE Information Return filing deadline?

For calendar-year taxpayers, the first GloBE Information Return filing deadline is 30 June 2026 — fifteen months after the close of the 2025 fiscal year. Groups with non-calendar year-ends have a corresponding 15-month window from their year-end. HMRC accepts filings via its dedicated Pillar Two portal.

How does Pillar Two affect financial statements?