Tech Leaders Outspend Supporters $10 to $1 in California Tax Fight

California voters will cast ballots on November 3 to decide the fate of Proposition 40, a proposed one-time 5 percent tax on the assets of the state's billionaires.

The campaign against the measure has become the most expensive ballot fight in history, according to David McCuan, a political science professor at Sonoma State University. Opponents have donated more than $300 million to block the tax. Supporters, by comparison, have raised only $32 million.

Major donors to the opposition include 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. Mark Zuckerberg, founder of Meta, has not personally donated to the campaign. However, Meta SEC filings indicate he told the board he would move his home out of state to avoid the tax. The board then created a new share class to help him pay the levy without affecting the company stock.

Voters have expressed confusion over conflicting mailers. Brian Galle, a University of California at Berkeley economics professor and co-author of the proposal, said he received a flyer claiming the tax would apply to retirement savings. He noted that language was not in the original text. Ashley Craig, a volunteer for the pro-tax group Patriotic Millionaires, said she frequently hears from voters who believe the measure contains secret provisions to tax everyone. Any changes to the tax would require a two-thirds majority in the assembly.

The spending gap has drawn criticism from experts. Galle stated that the billionaires are using their wealth to avoid the equality the tax aims to create. Francesco Trebbi, a professor at Berkeley's Haas School of Business, described the contest as "Sergey Brin v millions of Californians." The fight has also exposed a split among Democrats. Governor Gavin Newsom, who is considering a 2028 presidential run, opposes the measure, calling it "poorly written." He warned that the tax could cause billionaires, whose combined wealth is estimated at $2.3 trillion, to leave the state.

Opponents have also backed two other ballot measures that could nullify the tax if they receive more votes than Proposition 40. One measure bans new state taxes on personal property, while the other requires state auditors to review proposed tax measures before a vote. A recent Public Policy Institute of California poll found voters narrowly support the tax but also back the two countermeasures. Mark Baldassare, the institute's survey director, noted that only about a third of citizen initiatives pass, placing the burden of proof on the yes side.

Suzane Jiminez, chief of staff at the SEIU health workers union, said 3,000 volunteers are currently knocking on doors to support the measure. She noted that Senator Bernie Sanders and Congressman Ro Khanna have rallied support across the state. McCuan suggested that even a defeat could benefit backers, who might use the outcome to target big tech in future elections.