Taxing the Ultra-Rich

Introduction

The Brazilian Ministry of Finance introduced before the G20 a proposal to establish a global minimum tax on ultra-high-net-worth individuals (UHNWIs). The initiative, supported by reports from the Addis Tax Initiative (ATI), the Tax Justice Network, and analyses from professional advisors, aims to ensure that extreme concentrations of wealth contribute fairly to global public finances.

Summary of the Regulation

The proposal seeks to impose a minimum tax burden on the world’s wealthiest individuals regardless of where their assets are located. The concept behind the proposal is simple yet revolutionary: every billionaire, no matter where they reside, would be subject to a minimum effective tax rate on their global income and wealth.

According to the Addis Tax Initiative implementing a global minimum tax on High Net Worth Individuals across participating jurisdictions could yield up to USD 16 billion in additional revenue, equivalent to roughly 0.23 percent of GDP or 0.9 percent of total tax revenue in the countries studied. This would mark a new phase in fiscal coordination designed to curb tax base erosion and profit shifting through personal wealth mobility.

This global initiative finds resonance in recent developments within major economies. The United Kingdom’s 2025 abolition of the non-domiciled resident regime marked a decisive turn toward worldwide taxation of long-term residents, subjecting them to UK tax on income and gains earned anywhere in the world after four years of residence. Similarly, the United States under President Biden proposed extending its long-standing worldwide taxation principle by introducing a “billionaire minimum income tax” aimed at taxing unrealised gains of households with net worth exceeding 100 million USD, reinforcing the notion that wealth should contribute to taxation regardless of its form or jurisdiction.

These national initiatives parallel Brazil’s G20 proposal, reflecting a global policy convergence: major economies are beginning to close the gap between where wealth is created, where it is stored, and where it is taxed. The movement signals that the principles of fairness and fiscal accountability once limited to corporate taxation under the OECD’s Pillar Two framework are now being extended to individuals.

Implications for Businesses and Individuals:

From a practical standpoint, the proposed global billionaire tax would profoundly alter the landscape of personal and corporate tax compliance. For individuals, especially those with assets spread across several jurisdictions, the risk of double taxation becomes one of the most immediate concerns. Even though multilateral coordination and treaties aim to prevent overlapping tax claims, the coexistence of domestic rules and a global minimum framework could create instances where the same income or wealth is taxed twice once by the residence country and again through the top-up mechanism

Non-compliance would carry severe consequences. Failure to disclose assets, misrepresentation of foreign income, or the use of artificial arrangements to reduce effective taxation could trigger sanctions, ranging from monetary penalties to criminal proceedings under domestic anti-avoidance laws. In practice, this means that tax authorities would apply sanctions similar to those used in transfer pricing and corporate tax investigations, including interest surcharges, fines for non-cooperation, and potential reputational damage.

How can MCORE help?

MCORE LAW provides strategic guidance for high-net-worth individuals and corporations navigating this evolving tax landscape. Our advisory services focus on anticipating the operational, legal, and fiscal consequences of global tax coordination. We help clients evaluate their exposure under emerging minimum-tax regimes, redesign holding structures, and align their residency and asset management strategies with both domestic and international standards