Amid growing momentum for taxing the ultra-rich—spurred by Brazil’s G20 presidency in 2024—a new version of the Global Wealth Tax Simulator has been released. The announcement took place during the international conference “Taxing Billionaires”, held in Paris on April 8–9, 2025.

Organized by the PSE Stone Center in collaboration with the EU Tax Observatory and the World Inequality Lab, the conference brought together economists calling for a coalition of countries ready to place fiscal progressivity, equality, and planetary sustainability at the core of global economic relations.

The new simulator, developed by the World Inequality Lab, is an innovative tool for researchers, policymakers, and the public. Based on the methodology of Distributional National Accounts (DINA) and wealth rankings, it enables users to explore and compare tax scenarios in a consistent cross-country framework. This updated version draws on broader and more comprehensive wealth data than the initial release from 2022, with the aim of democratizing the debate around taxing high-net-worth individuals.

Two decades of DINA-based research have significantly expanded the World Inequality Lab's database, which now covers roughly three-quarters of global household wealth, with historical data dating back to the early 1900s for some countries.

At the conference, findings were presented that reveal surprisingly similar patterns of billionaire wealth accumulation and consistently low effective tax rates. Accounting for all taxes, the ultra-rich pay proportionally less than other groups, while working and middle classes often pay significantly more—depending on the country.

As wealth tax proposals gain traction from India to France, the Global Wealth Tax Simulator aims to empower public debate by making wealth tax scenarios accessible and comparable across borders.