California’s Billionaire Tax Fight Puts Silicon Valley on the Ballot

SACRAMENTO, Calif. — Proposition 40 would impose a one-time 5% levy on California residents with a net worth exceeding $1 billion. Sponsored by the Service Employees International Union-United Healthcare Workers West (SEIU-UHW), the initiative is projected to raise roughly $100 billion for programs intended to protect the state’s healthcare network from federal funding reductions.

The measure has also drawn opposition from Gov. Gavin Newsom, technology executives, business groups, and some labor unions. Those unions argue that dedicating the revenue exclusively to healthcare could reduce funding flexibility for education, infrastructure, and other public services.

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CALIFORNIA WEALTH TAX INITIATIVES
┌────────────────────────────────────────────────────────────────────────┐
│ PROPOSITION 40 │
│ • One-time 5% tax on residents with net worth over $1 billion │
│ • Estimated revenue: $100 billion dedicated to healthcare programs │
│ • Sponsored by SEIU-United Healthcare Workers West │
├────────────────────────────────────────────────────────────────────────┤
│ PROPOSITION 41 (Competing Measure) │
│ • Requires new tax revenues to comply with state spending limits │
│ • Designed to restrict appropriation of large tax windfalls │
├────────────────────────────────────────────────────────────────────────┤
│ PROPOSITION 42 (Competing Measure) │
│ • Prohibits state taxes on financial assets and personal property │
│ • Explicitly restricts wealth taxes outside of real estate │
└────────────────────────────────────────────────────────────────────────┘
“`

Two counter-initiatives will appear alongside Proposition 40 in November. Proposition 41 would require newly generated tax revenues to comply with California’s constitutional spending caps, limiting how the state could allocate unexpected windfalls. Proposition 42 would create a constitutional ban on state and local taxes on intangible personal property and financial assets, leaving real estate as the only permitted target.

California election law provides that when conflicting ballot propositions pass in the same election, the measure receiving the most affirmative votes takes precedence over overlapping provisions. A Public Policy Institute of California (PPIC) survey found that all three measures have majority support among likely voters, although the margins differ.

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PPIC VOTER SURVEY RESULTS
Proposition Yes No Margin
───────────────────────────────────────────────
Prop 40 (Tax) 52% 46% +6%
Prop 41 (Limits) 51% 44% +7%
Prop 42 (Ban) 54% 43% +11%
───────────────────────────────────────────────
Source: Public Policy Institute of California
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Proposition 40 holds a narrow lead, with 52% of likely voters supporting it and 46% opposed. Proposition 41 leads 51% to 44%, while Proposition 42 leads 54% to 43%. “Supporters of Proposition 40, the so-called billionaire tax initiative, have a lot of work to do,” Mark Baldassare, survey director at the Public Policy Institute of California, said in an interview with public broadcaster KQED.

The initiative has made California a national proving ground for wealth taxation, attracting substantial financial contributions and sharpening arguments over economic competitiveness, income inequality, and state tax policy. The campaign received academic backing Saturday through an endorsement letter signed by six recipients of the Nobel Memorial Prize in Economic Sciences: Daron Acemoglu, Abhijit Banerjee, Peter Diamond, Esther Duflo, Paul Krugman, and Joseph Stiglitz.

California depends heavily on high earners for general fund revenue. The top 1% of income earners have historically generated roughly half of the state’s personal income tax collections, a reliance that has contributed to Newsom’s long-standing opposition to wealth taxes and his concerns about budget volatility.

The Nobel laureates wrote that capital concentration among California’s ultra-wealthy has outpaced standard income tax systems. Their calculations put the state’s billionaire population at roughly 250 people, holding combined assets of $2.3 trillion. From 2019 through 2025, those individuals gained $1.4 trillion in wealth, while their state income tax payments amounted to approximately 1.6% of that increase.

“California is the right place to take this historic step,” the economists wrote. “The explosive growth of the state’s billionaires over the past few decades has made it one of the most unequal places in America.” They acknowledged that ultra-high-net-worth individuals have contributed significantly to technological and economic advancement, but argued that existing tax structures allow substantial capital returns to avoid taxation.

U.S. Rep. Ro Khanna, a Democrat who represents portions of the Bay Area tech corridor, has endorsed taxing excessive wealth accumulation while urging caution over implementation. He said illiquid holdings and voting shares in private enterprises should be exempted to prevent disruptions to corporate control.

Corporate leaders remain divided. Sergey Brin, the Google co-founder, has become a primary financial backer of the opposition campaign, contributing more than $100 million to defeat Proposition 40. Jensen Huang, Nvidia’s chief executive, has taken a neutral-to-supportive position, saying publicly that he is “perfectly fine” with the proposed tax.

Startup founders and investors, represented by industry trade groups, have warned that applying a 5% levy to paper valuations could penalize illiquid founders and early investors. They could be forced to sell assets to pay tax bills before their companies reach public liquidity.

The Nobel laureates rejected claims that Proposition 40 would suppress venture investment. They said California received 80% of all new U.S. venture capital funding since the beginning of 2026, up from roughly 50% before 2025, even though public discussion of the wealth tax began in late 2025.

The targeted wealth base is continuing to grow alongside artificial intelligence and public-market listings. Aerospace company SpaceX completed an initial public offering in June, while artificial intelligence developers Anthropic and OpenAI are preparing for public debuts over the next year, potentially adding new members to California’s billionaire roster.

“If the state that houses some of the country’s most powerful billionaires votes to tax their wealth, it will kickstart a movement to tax ultra-high-net-worth individuals in other states — and eventually at the federal level and in other countries,” the laureates wrote. “As Californians head to the polls, their vote may well come to be seen as a turning point in the battle between democracy and oligarchy.”

Voters will resolve the multi-measure contest when ballots are tallied on Nov. 3.