Sergey Brin Leads $187M Fight Against California Wealth Tax Prop 40

Google cofounder Sergey Brin has contributed $102 million to defeat Proposition 40, a November ballot measure that would impose a one-time 5% tax on California’s estimated 200 billionaires. His donation makes him the single largest funder of the opposition campaign, which has raised more than $187 million total through the political action committee Building a Better California. Supporters of the wealth tax have raised approximately $32 million.

Proposition 40 targets individuals with net worth exceeding $1 billion and directs 90% of projected revenue toward Medi-Cal, the state’s health care program for low-income residents. The remaining 10% would fund education, food assistance, and administrative costs. Legislative analysts estimate the measure could generate up to $100 billion over five years. For Brin, whose net worth approaches $260 billion, the personal liability under the proposal would be roughly $13 billion.

The spending disparity reflects a broader mobilization among technology executives who view the tax as an existential threat to California’s business climate. Former Google CEO Eric Schmidt and PayPal cofounder Peter Thiel have also donated to opposition efforts. Brin has framed his resistance in personal terms, citing his family’s 1979 emigration from the Soviet Union. In an April statement to The New York Times, he characterized the proposal as reminiscent of socialist policies that created an “oppressive society” and warned against California following a similar path.

Governor Gavin Newsom has aligned with tech leaders against the measure despite his party’s traditional support for progressive taxation. He argues the tax would ultimately reduce funding for teachers, childcare, public safety, and firefighting by accelerating capital flight and eroding the state’s long-term tax base. This position places him at odds with labor unions and healthcare advocates who championed Proposition 40 as a remedy for California’s nation-leading poverty rate of 18%.

Evidence suggests the governor’s concerns about immediate fiscal damage may be overstated relative to current tax contributions. A May working paper from the National Bureau of Economic Research found that California billionaires paid $4.1 billion in state income tax last year, representing just 0.2% of their collective $2 trillion net worth. At current payment rates, it would take approximately 25 years of lost income tax revenue from every billionaire leaving the state to offset the $100 billion Proposition 40 is projected to raise. Even if 25% of the state’s wealthiest residents departed, researchers calculated it would take a century for annual income tax losses to equal the one-time levy’s proceeds.

Capital flight is already occurring regardless of these projections. State records show Brin now lists Nevada as his primary residence. Fellow Google cofounder Larry Page incorporated his family office, Koop, and the ocean science nonprofit Oceankind in Delaware in December 2025. Brin also purchased a $51 million property near Miami Beach in March. Six prominent billionaires identified as likely departures—including Don Hankey, Travis Kalanick, and Steven Spielberg—collectively generated about $27 billion in historical tax revenue, equivalent to roughly one-quarter of Proposition 40’s five-year projection.

The divergence between empirical tax data and relocation behavior highlights the central tension in California’s wealth tax debate. While economic models suggest the state could absorb significant outmigration without negating the measure’s fiscal benefits, individual financial decisions are driven by forward-looking risk assessment rather than retrospective revenue analysis. The outcome of the November vote will determine whether California establishes the first statewide billionaire tax in U.S. history or reinforces existing barriers to direct wealth taxation.