Tech Founders Spend $300 Million to Defeat California Billionaire Tax

California voters will cast ballots on November 3 to determine whether a one-time 5 percent tax on billionaire assets will take effect. The campaign against the measure, known as Prop 40, has become the most expensive ballot fight in state history, according to David McCuan, a political science professor at Sonoma State University who tracks local elections.

Opposition donors have contributed more than $300 million to block the tax. This sum includes contributions from 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. Supporters of the tax have raised only $32 million, creating a spending disparity of nearly ten to one.

Mark Zuckerberg, founder of Meta, has not donated to the opposition. However, Meta’s SEC filings indicate that he informed the company’s board, which includes Xu and Collison, of his intent to purchase a home outside California to avoid the tax. The board subsequently created a new class of shares for Zuckerberg to pay the tax, a move that could have impacted Meta’s stock price if his relocation had been handled differently.

The volume of advertising has created confusion among some voters. Brian Galle, an economics professor at the University of California, Berkeley, and a co-author of the proposal, said a flyer he received claimed the tax could apply to retirement savings. Galle stated that such provisions were not in the original text. Ashley Craig, a volunteer with the pro-tax group Patriotic Millionaires, reported hearing similar complaints from voters about secret provisions. She noted that changing the tax would require a two-thirds majority in the state assembly.

Galle described the spending as ironic, noting that the tax aims to make democracy more equal, yet billionaires are using their wealth to avoid it. Francesco Trebbi, a professor at Berkeley’s Haas School of Business, characterized the contest as "Sergey Brin v millions of Californians." The fight has also exposed a split among Democrats. While the state party endorses the tax, Craig said she has received little ground support from it. Governor Gavin Newsom, who is considering a 2028 presidential run, opposes the measure, calling it "poorly written" and warning it could drive billionaires away from the state.

Opponents have also backed two other ballot measures. One would bar new state taxes on personal property or retroactive taxes, while the other requires state auditors to review proposed tax measures for financial impact. If either passes with more votes than the billionaire tax, it could negate the tax even if voters approve Prop 40. A recent Public Policy Institute of California poll found that voters narrowly support the tax but also back the two blocking measures. Mark Baldassare, the institute’s survey director, noted that only about a third of citizen initiatives pass, placing the burden on the yes side.

Suzane Jiminez, chief of staff at the SEIU health workers union which sponsored the measure, expressed confidence in the campaign. She said 3,000 volunteers have recently been knocking on doors and distributing flyers. Senator Bernie Sanders and Congressman Ro Khanna have also 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.