California voters are preparing to decide the fate of Proposition 40, a proposed one-time 5% wealth tax on taxpayers and trusts with assets exceeding $1 billion [1]. The measure would generate revenue to fund state healthcare programs, public education, and food assistance, with taxes payable over five years and covering businesses, securities, art, collectibles, and intellectual property—though real property, pensions, and certain retirement accounts would be exempt [1]. The tax would apply retroactively to those who were California residents as of January 1, 2026 [1].
Proponents, including UC Berkeley economists Gabriel Zucman and Emmanuel Saez alongside Paris School of Economics's Jasper Boll, estimate the wealth tax could raise approximately $100 billion over the five-year collection window from the roughly $2.3 trillion in wealth held by the state's billionaires in mid-2026 [1]. The economists argue that billionaires typically pay minimal income taxes due to deriving wealth from investments, and estimate the tax would have comparatively minor impacts on income tax revenue, as billionaires currently pay about $3 billion annually, representing 2.5% of California's income tax base [1]. However, this optimistic projection faces significant challenges, as the threat of the wealth tax has already prompted prominent billionaires to relocate, including Google co-founders Larry Page and Sergey Brin, Oracle founder Larry Ellison, and PayPal co-founder Peter Thiel [1].
A competing analysis from the Hoover Institution presents a more pessimistic outlook, with senior fellow Joshua Rauh and research fellow Benjamin Jaros finding that announced departures have already reduced the tax base by approximately 30%, with estimated collections falling short of projections [1]. This discrepancy highlights a critical tension: while proponents contend the tax would raise substantial revenue even after accounting for some departures and resulting income tax losses, critics warn that the wealth tax could permanently shrink the state's tax base over the long-term, with losses potentially exceeding near-term revenue gains [1]. The ballot measure has divided Democrats and Republicans, with opponents warning of potential negative economic consequences for California's future [1].
CONCLUSION
Proposition 40 presents a fundamental policy trade-off for California voters: the potential for $100 billion in near-term revenue for social programs versus the risk of accelerated wealth migration and long-term tax base erosion [1]. The 30% reduction in the billionaire tax base from announced departures suggests actual revenue may significantly underperform projections, making the measure's economic viability highly contested among economists [1].