California's billionaire tax: What's at risk for the biggest state economy in America

California voters will decide in November 2026 on a one-time 5% wealth tax on billionaires, the first such U.S. measure. Supporters, including professor David Gamage, argue it will fund healthcare and maintain quality of life. Opponents, including Governor Gavin Newsom and both major party candidates, warn it could drive wealthy residents and businesses out of the state, harming competitiveness. A state study predicts initial revenue in the tens of billions but long-term losses of hundreds of millions annually if billionaires leave. Norway's experience with wealth taxes shows mixed effects. The proposal is backed by the SEIU and opposed by lobbying from Google co-founder Sergey Brin, while Nvidia CEO Jensen Huang has expressed acceptance.