OECD Pillar One Two Global Minimum Tax: GloBE Mechanics

Key Takeaways

• Pillar One Amount A applies to roughly 100 groups with revenue over €20 billion and profit margin above 10%, reallocating 25% of residual profit to market jurisdictions via a new multilateral convention.
• Pillar Two applies to groups above €750 million in revenue and computes a GloBE effective tax rate per jurisdiction, topping up to 15% on income in any undertaxed subsidiary.
• Low-tax jurisdictions that adopt a Qualified Domestic Minimum Top-up Tax (QDMTT) keep the top-up revenue at home; those that refuse cede it to parent-country rules, creating a strong incentive for tax havens to enact QDMTTs.
• GloBE income and covered taxes are not simply book profit and book tax; they require dozens of adjustments for deferred tax, stock-based compensation, and minority interests, making ETR calculations operationally complex.

What It Is

The two pillars are distinct but complementary. Pillar One addresses the question of where multinationals pay tax. Amount A reallocates a portion of residual profits to market jurisdictions through a multilateral convention. Amount B simplifies arm's length pricing for routine distribution.

Pillar Two addresses how much tax they pay. Its GloBE (Global Anti-Base Erosion) Rules compute a jurisdictional effective tax rate for each in-scope group and apply a top-up tax equal to 15 percent minus that effective rate on excess profit in any undertaxed jurisdiction. The Subject-to-Tax Rule (STTR) is a complementary treaty-based provision allowing source countries to impose a minimum withholding on certain intra-group payments.

The Intuition

Under the old order, multinationals could legally book profit in low-tax jurisdictions by locating intangibles (brands, patents, algorithms) in those places. The result was that large, profitable digital and pharma groups paid single-digit effective rates in the aggregate. Two political coalitions converged on a fix.

Source countries wanted taxing rights over digital revenue earned in their markets without local presence. That is Pillar One Amount A. Residence countries wanted a floor on tax competition. That is Pillar Two. Bundling them together gave everyone enough to agree in October 2021, at least in principle.

How It Works

Pillar One Amount A

Amount A applies to groups with global revenue above EUR 20 billion and profit margin above 10 percent. For those groups, 25 percent of residual profit (profit above 10 percent of revenue) is reallocated to market jurisdictions based on where revenue is sourced. Nexus requires at least EUR 1 million in revenue per jurisdiction, with a lower threshold for small economies.

in-scope test  = revenue > EUR 20bn AND margin > 10%
residual       = profit - 10% * revenue
Amount A       = 25% * residual
allocation     = proportional to sourced revenue in each market jurisdiction

The revenue threshold is expected to drop to EUR 10 billion seven years after entry into force, contingent on successful implementation.

Pillar Two GloBE

Pillar Two applies to multinational groups with global revenue above EUR 750 million. It computes a jurisdictional effective tax rate and tops up to 15 percent.

GloBE ETR (jurisdiction) = covered taxes / GloBE income
top-up rate              = max(0, 15% - GloBE ETR)
top-up tax               = top-up rate * (GloBE income - substance carve-out)

The substance-based income exclusion allows a carve-out equal to 5 percent of payroll plus 5 percent of tangible asset value, phased in from 10 and 8 percent respectively during the transition period.

Three interlocking rules collect the top-up:

• The Qualified Domestic Minimum Top-up Tax (QDMTT) lets the jurisdiction where low-taxed income arises collect the top-up itself.
• The Income Inclusion Rule (IIR) taxes the parent on the top-up if the low-tax jurisdiction has not imposed a QDMTT.
• The Undertaxed Profits Rule (UTPR) allows other group jurisdictions to collect the residual top-up if neither QDMTT nor IIR applies.

Worked Example

Consider a multinational with EUR 40 billion in revenue and 20 percent profit margin, so EUR 8 billion in profit.

Pillar One Amount A test:

residual profit    = 8bn - 10% * 40bn = 4bn
Amount A           = 25% * 4bn = 1bn reallocated to market jurisdictions

If 40 percent of revenue is sourced in the EU, 30 percent in the US, 10 percent in India, 20 percent elsewhere, roughly EUR 400 million, 300 million, 100 million, and 200 million respectively are allocated as new taxing rights.

Pillar Two GloBE test on a subsidiary in a low-tax jurisdiction:

GloBE income            = EUR 500m
covered taxes           = EUR 40m
GloBE ETR               = 40/500 = 8%
top-up rate             = 15% - 8% = 7%
substance carve-out     = 5% payroll + 5% tangibles = EUR 50m
top-up tax base         = 500m - 50m = 450m
top-up tax              = 7% * 450m = EUR 31.5m

The EUR 31.5 million is collected by the low-tax jurisdiction (if QDMTT), the parent country (if IIR), or other group jurisdictions (if UTPR).

Common Mistakes

1. Confusing the two pillars. Pillar One is about where tax is paid. Pillar Two is about how much. They apply to different populations (roughly 100 groups vs thousands), through different mechanisms (convention vs domestic rules), and solve different problems.

2. Ignoring the QDMTT incentive. A low-tax jurisdiction that adopts a QDMTT keeps the top-up revenue at home. A jurisdiction that refuses to adopt effectively hands the revenue to foreign parent countries through the IIR. This has led many low-tax centres to enact QDMTTs quickly.

3. Overstating coverage. The GloBE rules apply to groups above EUR 750 million in revenue, not to every multinational. Middle-market groups remain outside the regime, although domestic pressure to extend coverage may grow.

4. Treating effective tax rate as straightforward. GloBE income starts from financial accounting and applies a long list of adjustments for deferred tax, stock-based compensation, minority interests, and other items. The ETR numerator and denominator are both technical concepts, not book tax divided by book profit.

5. Assuming universal adoption. As of 2026, adoption is uneven. The EU, UK, Japan, South Korea, Canada, and Australia have implemented. The United States has not adopted GloBE in full and in January 2026 signalled an exemption for US-headquartered multinationals. The practical result is a patchwork rather than a single global regime.

Frequently Asked Questions

Q: What are OECD Pillar One and Pillar Two in simple terms? Pillar One determines where large multinationals pay tax, it gives market countries a slice of profits earned from their customers. Pillar Two determines how much they pay, it sets a 15% floor by charging a top-up when any jurisdiction taxes income below that rate.

Q: How do Pillar One and Pillar Two affect investment decisions? For equity investors, they raise effective tax rates for companies that previously booked large profits in low-tax jurisdictions, compressing after-tax earnings. For fixed-income investors, they reduce corporate cash flows available for debt service in affected multinationals. The impact concentrates in tech, pharma, and financial sectors with mobile intellectual property.

Q: What is a real-world example of how the GloBE top-up works? A subsidiary in a 9% effective-rate jurisdiction earning €500 million of GloBE income pays €40 million in local tax. The top-up rate is 6% (15% minus 9%). After a substance carve-out of €50 million, the top-up applies to €450 million: 6% times €450 million equals €27 million collected by the parent's home country under the IIR, or by the low-tax jurisdiction itself if it has enacted a QDMTT.

Q: How can investors use knowledge of Pillar One and Pillar Two? Build a GloBE ETR sensitivity into earnings models for large multinationals. Companies disclosing country-by-country reporting data allow direct calculation of jurisdictions where the 15% floor will bite. Track QDMTT legislation in key low-tax centers, enactment signals the top-up has been internalized and will not surprise earnings later.

Q: How are Pillar One and Pillar Two different from each other? Pillar One reallocates existing taxing rights, it changes which country gets to tax profit, not the total tax paid. It applies to roughly 100 very large companies via a new multilateral treaty. Pillar Two creates additional tax where the total effective rate is below 15%, it adds to the total tax burden. It applies to thousands of groups above €750 million through domestic GloBE legislation.

Sources

1. OECD. "Pillar Two Rules in a Nutshell." https://www.oecd.org/content/dam/oecd/en/topics/policy-sub-issues/global-minimum-tax/pillar-two-model-rules-in-a-nutshell.pdf
2. OECD. "Pillar One Amount A Fact Sheet." https://www.oecd.org/content/dam/oecd/en/topics/policy-issues/cross-border-and-international-tax/pillar-one-amount-a-fact-sheet.pdf
3. OECD. "Minimum Tax Implementation Handbook (Pillar Two)." https://www.oecd.org/content/dam/oecd/en/topics/policy-sub-issues/global-minimum-tax/minimum-tax-implementation-handbook-pillar-two.pdf
4. OECD. "Global Anti-Base Erosion Model Rules (Pillar Two)." https://www.oecd.org/en/topics/sub-issues/global-minimum-tax/global-anti-base-erosion-model-rules-pillar-two.html

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.