A Pillar Two safe harbour is a provision that lets a multinational group treat its GloBE top-up tax as zero for a jurisdiction, without running the full GloBE computation, provided it meets a defined test. As of September 2026 there are six of them in circulation — not the two or three that most 2023-vintage explainers still describe — because the OECD published an entirely new package, the Side-by-Side (SbS) package, on 5 January 2026. If your compliance team is still working from the December 2022 Transitional CbCR Safe Harbour alone, you are missing three safe harbours that may already reduce your filing burden, and one that may not apply to you at all despite what your ERP vendor’s marketing claims.

The six safe harbours in force, at a glance

Two of these predate January 2026 and are well established. Four are new or newly extended under the Side-by-Side package. The European Commission confirmed on 12 January 2026, via a notice published in the Official Journal, that all five SbS-package safe harbours are covered by Article 32 of the EU Minimum Tax Directive (2022/2523) — meaning EU member states did not need to renegotiate the Directive itself to apply them, though most still needed domestic legislation to activate them.

QDMTTs themselves are unaffected by any of this: a market jurisdiction that has enacted a QDMTT keeps collecting it regardless of which safe harbour a group elects elsewhere. For the underlying GloBE mechanics these safe harbours sit on top of — the IIR, UTPR and DMTT/QDMTT themselves — see our Pillar Two Statement Country Tracker and overview of the global minimum corporate income tax.

Transitional CbCR Safe Harbour: how the extension actually works

The original safe harbour, published by the OECD in December 2022 as part of the Safe Harbours and Penalty Relief guidance, lets a group avoid the full GloBE calculation for a jurisdiction if it passes any one of three tests, using figures taken from the Country-by-Country Report and the consolidated financial statements rather than a separate GloBE computation:

• De minimis test: jurisdictional revenue below €10 million and profit before tax below €1 million.
• Simplified ETR test: simplified ETR at or above 15% for fiscal years beginning in 2023–2024, 16% for 2025, and — after the January 2026 extension — 17% for both 2026 and 2027.
• Routine profits test: profit before tax at or below the jurisdiction’s Substance-based Income Exclusion amount.

Two mechanics matter more than the thresholds themselves. First, the safe harbour runs on a Qualified CbC Report only — one prepared from the same accounting standard used for the consolidated statements, not a report assembled from local GAAP figures stitched together for filing purposes. A CbC Report built loosely for BEPS Action 13 compliance will not automatically qualify. Second, the “once out, always out” rule means that once a group fails to apply the safe harbour to a jurisdiction in an eligible year, that jurisdiction is permanently barred from the safe harbour going forward. There is no re-entry.

The January 2026 extension pushed the sunset from fiscal years ending on or before 30 June 2028 to fiscal years beginning on or before 31 December 2027 (not ending after 30 June 2029) — buying one more year before groups must rely on the permanent Simplified ETR Safe Harbour instead.

Permanent QDMTT Safe Harbour: the one that depends on your local law, not your calculation

This safe harbour, introduced through OECD administrative guidance and maintained on an OECD-published Central Record of qualifying legislation, deems GloBE top-up tax nil for a jurisdiction where a Qualified Domestic Minimum Top-up Tax already applies — so the group runs one calculation, the QDMTT, instead of two. Qualification is not automatic: the QDMTT has to meet three standards.

The Accounting Standard restricts which financial accounting standard the QDMTT can be based on. The Consistency Standard requires the QDMTT’s computation to mirror the GloBE Rules except for a short list of explicitly permitted deviations (a narrower substance-based income exclusion, a narrower de minimis exclusion, or a rate above 15%); a “switch-off rule” disqualifies a QDMTT that excludes flow-through entities, investment entities or certain joint-venture groups from its base in a way the GloBE Rules do not. The Administration Standard requires the jurisdiction to maintain ongoing monitoring consistent with GloBE implementation. The practical implication: do not assume every domestic top-up tax marketed as a “QDMTT” automatically carries safe harbour status — check the OECD’s Central Record for the specific jurisdiction and fiscal year before relying on it.

Simplified ETR Safe Harbour: the permanent replacement, arriving in 2027

This is the safe harbour designed to outlive the transitional CbCR mechanism. It deems top-up tax nil where a jurisdiction’s Simplified ETR — calculated from financial accounting data drawn from the consolidated reporting package, with a limited, defined set of adjustments rather than a full GloBE recomputation — is at or above 15%. It generally applies from fiscal years beginning on or after 31 December 2026 (effectively FY2027), with early adoption permitted from 31 December 2025 in specified circumstances. A group that elects out of it in a given year, or fails to qualify, faces a 24-month re-entry restriction before it can elect back in.

Substance-Based Tax Incentives Safe Harbour: what changes for R&D credits and green subsidies

Before this safe harbour, a refundable or creditable tax incentive tied to genuine economic activity — payroll-linked R&D credits, production credits for clean energy manufacturing — could still erode a jurisdiction’s GloBE effective tax rate under the standard Covered Taxes definition, even though the incentive rewarded real substance rather than profit-shifting. From fiscal years beginning on or after 1 January 2026, a qualifying expenditure-based or production-based incentive is instead added back to Covered Taxes, up to a cap calibrated against the jurisdiction’s payroll and tangible-asset substance (with an elective alternative based on the carrying value of tangible assets over a five-year period), which reduces or eliminates the resulting top-up tax rather than inflating it. Not every incentive qualifies: purely timing-based incentives that only accelerate a deduction, without creating a permanent difference such as a true super-deduction, are excluded. This is the safe harbour most likely to matter for groups with US R&D credit exposure or EU/UK green-manufacturing incentives, and it is worth re-checking any GloBE model built before January 2026 that treated those credits as straightforward ETR drag.

Side-by-Side and UPE Safe Harbours: the ones that depend on where your parent sits

These are the most structurally different additions, because eligibility does not depend on a group’s own numbers — it depends on whether the Ultimate Parent Entity’s home jurisdiction has been formally listed by the OECD as a “Qualified” jurisdiction under one of two tests.

The Side-by-Side Safe Harbour deems both IIR and UTPR top-up tax nil, group-wide, for MNE groups whose UPE sits in a jurisdiction that operates: a domestic tax system with a nominal corporate rate of at least 20% and a QDMTT or financial-statement-based alternative minimum tax of at least 15%; and a worldwide tax system that taxes both active and passive foreign income of resident corporations broadly, without material carve-outs, and credits foreign minimum taxes and QDMTTs. As of the January 2026 publication and still as of this writing, only the United States has been listed as meeting both tests — this was the mechanism through which the January 2026 package, following a G7 political agreement from June 2025, effectively exempted US-parented groups from IIR/UTPR exposure on their foreign operations, while their QDMTT liabilities in market jurisdictions remain untouched.

The UPE Safe Harbour is narrower: it only requires the domestic-system test (20% nominal / 15% QDMTT-or-AMT), not the worldwide-system test, and it only zeroes out UTPR exposure on profits earned in the UPE’s own jurisdiction — it does nothing for IIR or for the group’s foreign subsidiaries. No jurisdiction had been listed as qualifying for it as of this writing. A foreign-parented group cannot access either safe harbour by restructuring a mid-tier holding company into a qualifying jurisdiction; the test looks at the Ultimate Parent Entity specifically.

Is the EU actually applying these yet?

Legally, yes, since 12 January 2026: the European Commission’s notice confirmed that the conditions of Article 32 of the EU Minimum Tax Directive — which allows safe harbours agreed at OECD/Inclusive Framework level to apply automatically without amending the Directive — were met for all five safe harbours in the SbS package, after Cyprus (not an Inclusive Framework member) gave its consent on 8 January 2026. The Commission was explicit that it does not intend to amend the Directive itself.

Operationally, implementation is fragmented and, in most member states, still in progress as of September 2026. Throughout the year, national governments have been publishing draft legislation at different paces and to different extents: Germany introduced the Side-by-Side and UPE safe harbours in its draft Annual Tax Act in May 2026 and published a jurisdiction-by-jurisdiction qualifying list in August; Sweden proposed amendments covering four of the five safe harbours in August; Luxembourg and Norway drafted legislation covering the permanent Simplified ETR Safe Harbour and the full package respectively; the UK published draft legislation for the permanent Simplified ETR Safe Harbour, the extended Transitional CbCR Safe Harbour and the SBTI treatment in August; Slovakia’s government approved draft legislation for the SBTI and extended CbCR safe harbours the same month; the Netherlands has said it will submit its own SbS-package legislative proposal only by summer 2026, after stakeholder consultation. None of this is finalised law everywhere yet. A compliance team should not assume a given safe harbour is available in a specific EU jurisdiction for the current fiscal year without checking that jurisdiction’s actual enacted (not merely drafted) legislation, since domestic effective dates and drafting details still vary by country even where the underlying OECD test is identical.

What doesn’t qualify: the failure points that come up in practice

Four situations account for most of the “I thought we qualified” surprises reported so far:

• A CbC Report that isn’t “Qualified.” If the underlying CbC Report mixes accounting standards across constituent entities, or wasn’t prepared from the same consolidated-accounts data used for the group’s financial statements, it cannot support the Transitional CbCR Safe Harbour or the Simplified ETR Safe Harbour, regardless of the resulting ETR.
• A nominal rate that looks high but isn’t matched by an AMT or QDMTT. The Side-by-Side and UPE tests both require the 20% nominal-rate condition and a separate 15% QDMTT-or-AMT condition on financial-statement income. A jurisdiction with a 25% headline corporate rate but no qualifying minimum tax mechanism does not pass.
• Assuming a mid-tier parent can access Side-by-Side. The test looks exclusively at the Ultimate Parent Entity’s jurisdiction. A US-headquartered sub-group inside a non-US global UPE does not get the Side-by-Side exemption merely because its immediate business unit is American.
• Treating a timing incentive as substance-based. An incentive that merely accelerates a deduction without creating a permanent book-tax difference does not qualify for the SBTI safe harbour, even if it is genuinely tied to payroll or capital expenditure.

And once a group elects out of the Transitional CbCR Safe Harbour for a jurisdiction — or fails one of its tests in an eligible year — the “once out, always out” rule closes that door permanently for that jurisdiction, even after the Simplified ETR Safe Harbour becomes generally available in 2027.

What this means for compliance teams right now

Three actions are worth doing before year-end 2026 close. First, re-map which of the six safe harbours each jurisdiction in your structure could plausibly access, rather than relying on a 2023 or 2024 Pillar Two model that only accounts for the original transitional CbCR mechanism. Second, if your UPE sits in the US, confirm with your advisers whether electing into the Side-by-Side Safe Harbour changes your GloBE Information Return filing position for FY2026 — it still has to be elected and disclosed, not assumed. Third, for each EU jurisdiction where you operate, verify the safe harbour’s actual enactment status rather than its OECD-level availability; a safe harbour that is live at OECD and EU-directive level can still be unavailable locally until national legislation catches up.

FAQ

Do all six Pillar Two safe harbours apply automatically?
No. The Transitional CbCR, permanent QDMTT and SBTI safe harbours generally require an annual election in the GloBE Information Return; the Side-by-Side and UPE safe harbours depend on the UPE jurisdiction being formally listed as qualifying by the OECD, and still require an explicit election once available.

Can a group use more than one safe harbour at the same time?
Yes, on a jurisdiction-by-jurisdiction basis. A group’s US operations might rely on the Side-by-Side Safe Harbour for IIR/UTPR while a separate low-risk jurisdiction elsewhere in the structure qualifies independently under the Transitional CbCR or QDMTT safe harbour.

Does the Side-by-Side Safe Harbour eliminate QDMTT liability for US groups?
No. It only zeroes out IIR and UTPR top-up tax. Market jurisdictions with an enacted QDMTT continue collecting it on local low-taxed profits regardless of the parent’s Side-by-Side status.

What happens to the Transitional CbCR Safe Harbour after 2027?
It expires for fiscal years beginning after 31 December 2027. The permanent Simplified ETR Safe Harbour, generally available from fiscal years beginning on or after 31 December 2026, is the intended successor, though the two have different qualifying-data requirements.

Further Reading

The ‘Pillar Two’ Global Minimum Tax (Elgar Tax Law and Practice series), edited by Werner Haslehner, Georg Kofler, Katerina Pantazatou and Alexander Rust, is a current academic and practitioner reference covering the GloBE Rules in depth: available on Amazon.co.uk.