California's billionaire tax could spark global wealth tax movement
Nobel economists endorse a 5% levy on billionaires' assets as a historic step against inequality.
1Nobel economists endorse wealth tax
Six Nobel Prize-winning economists, including Daron Acemoglu and Joseph Stiglitz, publicly supported California's Proposition 40. The measure proposes a one-time 5% tax on assets exceeding $1 billion. They argue California's extreme wealth concentration makes it the ideal testing ground for such policy. The state's 250 billionaires saw their wealth grow by $1.4 trillion from 2019-2025 while paying just 1.6% in state income taxes on those gains.
2Potential $100 billion revenue
The Service Employees International Union estimates the tax could generate $100 billion, potentially offsetting federal healthcare cuts. Supporters highlight how California's ultra-rich would remain among the world's wealthiest even after the levy. The tax targets liquid assets but exempts illiquid stakes and voting shares after opposition from some lawmakers. Critics argue it could force founders to sell large company portions, though proponents note the AI boom continues enriching tech elites.
3Political and business divisions
Governor Gavin Newsom opposes the tax while Congressman Ro Khanna supports it with reservations. Tech leaders are split: Nvidia's CEO supports it while Google's co-founder donated $100M against it. The measure has divided unions too, with some prioritizing other spending areas. Three competing propositions (41, 42) that would limit or nullify the wealth tax currently have majority support, setting up a complex ballot showdown in November.
4California's VC dominance continues
Despite billionaire tax fears emerging in late 2025, California attracted 80% of all new US venture capital funding since 2026, up from 50% pre-2025. The economists argue this disproves claims the tax would harm Silicon Valley. They cite SpaceX's June IPO and upcoming offerings from Anthropic and OpenAI as evidence the tech ecosystem remains robust. The state added 20 new billionaires through these deals despite the tax proposal.
5Global implications
Economists predict California's move could inspire similar taxes elsewhere, calling it a potential turning point in wealth redistribution. They note the state houses many of America's most powerful billionaires, making their taxation symbolically significant. The letter frames the vote as a battle between democracy and oligarchy. However, recent polls show only 52% support for Prop 40 versus 46% opposition, with the outcome potentially decided by narrow margins.
6Tax avoidance concerns
The economists highlight how billionaires currently use loopholes to avoid taxes on capital returns, allowing wealth to compound untaxed. They contrast this with the working class who pay higher effective rates. The 5% levy targets this accumulation directly rather than annual income. Opponents counter that wealth taxes are difficult to administer and may drive billionaires to relocate, though supporters note California's unique concentration of tech wealth provides leverage.
7Inequality metrics
California's billionaire class grew explosively in recent decades, creating one of America's most unequal states. The top 250 billionaires hold $2.3 trillion collectively. Their tax payments haven't kept pace with wealth growth—from 2019-2025 they paid just 1.6% in state taxes on $1.4 trillion in gains. The economists argue this disparity undermines social cohesion and public services while concentrating political power among the ultra-wealthy.
8November showdown
The wealth tax faces three competing measures on the November ballot. Proposition 41 would subject new taxes to spending limits (51% support), while Proposition 42 would ban taxes on financial assets (54% support). Polls show Prop 40 at 52% approval, making voter turnout critical. The Service Employees International Union must overcome well-funded opposition from tech billionaires. Passage could establish California as a global leader in wealth taxation policy.
Original article: Fortune — California's billionaire tax could spark global wealth tax movement