Tech Donors Pour $300 Million Into California Tax Fight

California voters will decide on November 3 whether to impose a one-time 5 percent tax on the assets of the state's billionaires.

Opponents have raised more than $300 million to defeat the measure, known as Prop 40. This sum makes it the most expensive ballot campaign in state history, according to David McCuan, a political science professor at Sonoma State University who tracks such races. The funding comes from major tech figures, including Google co-founder Sergey Brin, DoorDash founder Tony Xu, and venture capital leaders John Doerr, Michael Moritz, and Vinod Khosla. By comparison, supporters of the tax have gathered only $32 million.

The disparity in funds has fueled a wave of advertising and mailers that has confused some residents. Brian Galle, a Berkeley economics professor who helped draft the proposal, noted that flyers claimed the tax could target anyone, including retirement savings. He stated that those details were not part of the original text. Ashley Craig, a volunteer for the pro-tax group Patriotic Millionaires, reported hearing similar claims about secret provisions from constituents. She emphasized that any modification to the tax would require a two-thirds majority in the assembly and must preserve the measure's intent.

Political dynamics add another layer to the contest. Governor Gavin Newsom, who is considering a 2028 presidential run, opposes the tax. He described it as poorly written and warned it could drive billionaires, whose combined wealth is estimated at $2.3 trillion, out of the state. Gubernatorial candidate Xavier Becerra and former congresswoman Katie Porter share that view. The fight also tests the unity of the Democratic Party, which has officially endorsed the tax but offered limited ground support, according to Craig.

Opponents are also backing two additional ballot measures designed to block or negate the billionaire tax if it passes. One proposal bars new state taxes on personal property or retroactive levies. The other requires state auditors to review financial impacts before a vote. A recent Public Policy Institute of California poll shows voters narrowly support the tax but also back these defensive measures. Mark Baldassare, the institute's survey director, noted that only about one-third of citizen initiatives succeed, placing the burden of proof on the yes side. Suzane Jiminez, chief of staff for the SEIU health workers union that sponsored the measure, remains confident. She pointed to 3,000 volunteers currently canvassing and support from Senator Bernie Sanders and Congressman Ro Khanna.