Billionaires Mobilize Over $300 Million to Block California’s One-Time Wealth Tax

California voters will decide on Proposition 40 in the 2026 election. The measure would impose a one-time 5 percent tax on residents whose net worth exceeds $1 billion, targeting assets such as stock, art and intellectual property. Campaign-finance filings reviewed by *The Standard* show that billionaire-backed groups have poured more than $300 million into a coordinated effort to defeat the tax and to support competing measures (Propositions 41 and 42) that would nullify it.

Boston Globe

Prop 40 emerged as a response to projected federal Medicaid cuts that could cost California $100 billion over five years. Supporters, led by the health-care workers’ union SEIU-UHW, argue the tax would fund the shortfall. Opponents contend the tax is unconstitutional and could trigger a “wealth exodus,” burdening the state’s economy.

Boston Globe

• Total opposition spending: $300 million–$340 million.

San Francisco Standard

• Advertising: $144 million on digital and television ads, 86 % aired in September–October 2026.

San Francisco Standard

• Signature gathering: $99 million paid to PCI Campaigns Inc. for rapid collection of signatures for Props 41 and 42, at up to $15 per signature.

San Francisco Standard

• Other costs: $23 million on mailers, $22 million on consulting, $1.8 million on text messaging, and $750,000+ on polling.

San Francisco Standard

• Primary donor: Tech billionaire Sergey Brin contributed more than half of the total opposition budget.

Forbes

Sean McMorris emphasized that professional signature-gathering firms are scarce and command high fees, noting that “you need hired professionals to secure enough signatures and navigate the law to ensure everything is done correctly.” Davina Hurt warned that the high cost of ballot-measure infrastructure may limit participation to those with substantial financial resources, questioning whether the initiative process still serves its original purpose of giving ordinary citizens a voice. Palmer Luckey argued that the tax would affect unrealized assets and super-voting shares, and expressed concern that the measure could drive tech talent and companies out of the state.

San Francisco Standard

Critics argue the tax could undermine California’s competitive edge. Business groups cite the relocation of billionaires such as Brin and Page as evidence of a “wealth exodus.” Legal scholars point to the lack of constitutional grounding for a one-time wealth levy, while ethics advocates highlight the disparity between the $340 million opposition war chest and the $32 million raised by the tax’s sponsor.

Forbes

• *The Standard* reports opposition spending of “more than $300 million.”

San Francisco Standard

• Forbes cites “more than $340 million” raised by opponents.

Forbes

• The Guardian is referenced for a $340 million figure, while *The Standard* also notes $330 million contributed to the PAC “Building a Better California.”

San Francisco Standard

These variations reflect differing accounting periods and inclusion criteria for ancillary expenses such as polling and consulting.

California faces pressure over broadband funding conditions.

The 2026 ballot will determine whether Prop 40 passes. If approved, the state will assess a one-time 5 percent levy on the net worth of roughly 250 California residents. Opponents have indicated they will continue to fund legal challenges and public-relations campaigns through the election’s final weeks.

A Difference of Opinion Columnists: Should California voters approve or oppose Proposition 4?