California Billionaire Tax Faces Uncertain Fate as Opponents Pour In Record Spending

California voters will decide on November 3 whether to impose a one-time 5 percent tax on the assets of the state's billionaires, and the campaign against it has become the most expensive ballot measure fight ever, according to David McCuan, a political science professor at Sonoma State University who tracks state and local elections.

Opponents, including Google co-founder Sergey Brin, DoorDash founder Tony Xu, Stripe co-founder Patrick Collison, Ripple co-executive chairman Chris Larsen and venture capitalists John Doerr, Michael Moritz and Vinod Khosla, have donated more than $300m to block the measure, known as Prop 40. Supporters have raised only $32m.

Meta founder Mark Zuckerberg has not given money to the opposition. However, Meta's SEC filings showed he told the company's board, which includes Xu and Collison, that he would buy a home outside California to avoid the tax. The board then created a new class of shares that Zuckerberg could use to pay it, since his move could have affected Meta's stock price.

The flood of advertising and mailers has left some voters confused. Brian Galle, a University of California at Berkeley economics professor who helped write the proposal, said a flyer he received claimed the tax could apply to anyone, including their retirement savings. He said those claims were not in what he wrote. Ashley Craig, a volunteer with the pro-tax group Patriotic Millionaires, said she often hears from voters that the measure has secret provisions that would tax everyone. Any change to the tax would need a two-thirds majority in the assembly and would have to stay true to the spirit of the measure.

Galle argued that the spending shows the problem the tax aims to address. "The irony is that Prop 40 is meant to make democracy more equal, but the billionaires are using their money to avoid that," he said, pointing to the Supreme Court's Citizens United v FEC ruling. Francesco Trebbi, a professor at Berkeley's Haas School of Business, said the contest amounts to "Sergey Brin v millions of Californians" and erodes trust in the system.

The fight also reflects a split among Democrats. The state party has endorsed the tax, but Craig said she has received little ground support from it. McCuan described the measure as a proxy test between progressives and moderates, and said a success could encourage progressive candidates to try similar ideas in the 2028 presidential race. Governor Gavin Newsom, who is eyeing a 2028 run, opposes the tax, calling it "poorly written" and warning it would harm the state if billionaires, whose wealth the authors estimate at 2.3 trillion, leave. Gubernatorial candidate Xavier Becerra and former congresswoman Katie Porter also oppose it.

Opponents have also backed two other ballot measures. One bars new state taxes on personal property or those imposed retroactively, and the other requires state auditors to review proposed tax measures for financial impact before a vote. If either passes with more votes than the billionaire tax, it could negate the tax even if voters approve it.

A recent Public Policy Institute of California poll found voters narrowly support the tax, but they also back the two measures aimed at stopping it. Mark Baldassare, the institute's statewide survey director, noted that only about a third of citizen initiatives pass, so the burden is on the yes side. He plans to poll again as voters receive state guides explaining the measures.

Suzane Jiminez, chief of staff at the SEIU health workers union, which sponsored the measure, said she feels confident. She said 3,000 volunteers have recently been knocking on doors and distributing flyers, and that Senator Bernie Sanders and Congressman Ro Khanna have rallied support across the state. McCuan suggested that even a defeat could benefit backers, who could blame moderates and target big tech as a political bogeyman.