Inequality

Taxing Extreme Wealth: What Countries Around the World Could Gain from Progressive Wealth Taxes

Presented at Paris School of Economics

Using data from the World Inequality Database, we estimate the revenue potential of a moderate, progressive net wealth tax for 173 countries, calibrated on Spain's "solidarity surcharge." We find that such a tax could raise approximately US$1.9 trillion globally — on average, a 6.1% increase in government budgets.

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Abstract

In light of the global challenges of climate change, the cost of living crisis, high debt levels, and the risk of authoritarian rule, countries need stable and reliable revenue sources that do not harm their economies and societies. A moderate, progressive tax on net wealth is a tool to generate this revenue. Taxing extreme wealth not only addresses the problem of the regressivity of the income tax system for the ultra-rich but also reduces overlapping inequalities and ensures that those who have contributed the most to the planet’s destruction pay their fair share. This paper presents country-level estimates for 173 countries on the revenue potential from implementing a moderate, progressive tax on net wealth. We draw on the example of Spain’s “solidarity surcharge,” a model that has proven politically feasible, and use data from the World Inequality Database to project the revenues of adopting similar tax measures around the world. Our analysis indicates that such a tax could lead to an average budget increase of 6.1%. This equates to a potential global revenue of approximately US$1.9 trillion, which is over four times the investment required for countries to collectively adapt to climate change.

Coauthored with Miroslav Palanský

The Precious Networks of the Rich: How the Wealthiest Shape the Tax Agenda

We test whether social and institutional ties between legislators and the ultra-rich help explain trends toward regressive taxation.

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Scheduled for the IIPF Annual Meeting 2026.

Abstract

Despite broad public support for progressive taxation, the current U.S. tax system is among the most regressive in history. This paper tests whether social and institutional ties between legislators and the ultra-rich help explain this mismatch. We use large language models to classify the progressivity of the full universe of tax-related bills introduced in Congress since 1973. Using publicly available biographies, we then construct a new dataset linking Members of Congress to billionaires through overlap in higher-education institution, program, and graduation cohort. Our preliminary findings suggest that legislators with greater exposure to billionaires during college and university are more likely to sponsor regressive tax proposals and fewer progressive ones. These results support the view that elite networks can transmit political influence through informal social channels.