Proposition 40 is a California ballot measure that would impose a one-time 5% tax on the net worth of every billionaire who lived in the state as of January 1, 2026.
Voters decide on it in the November 3, 2026 election, and it needs a simple majority to pass. The measure aims to raise about $100 billion to offset federal funding cuts to California’s health-care system, and it was championed by the SEIU-United Healthcare Workers West union. A little more than 200 billionaires live in the state; Meta’s Mark Zuckerberg alone could owe as much as $12.5 billion. Because the tax is retroactive to January 1, at least six billionaires, including Google co-founders Larry Page and Sergey Brin and investor Peter Thiel, reportedly left California before that date. Governor Gavin Newsom opposes the measure, warning that it could drive out wealthy residents and their income tax revenue, while Nvidia CEO Jensen Huang and Senator Bernie Sanders have backed it. A September Berkeley IGS and Los Angeles Times poll found 45% of likely voters in favor, 42% opposed, and 13% undecided.
Image: California State Capitol, Ttoolan, CC BY-SA 3.0, via Wikimedia Commons.