California billionaires are intensifying efforts to defeat Proposition 40, a proposed wealth tax targeting the state's billionaires, ahead of the November 3, 2026 election. Notable figures such as Google co-founder Sergey Brin, venture capitalist John Doerr, and Ripple co-founder Chris Larsen have collectively raised over $300 million in opposition to the measure.

The increased funding suggests stronger opposition to Proposition 40, and market pricing implies a decreased likelihood of the wealth tax passing. Support for the measure has declined in recent polling, consistent with the stepped-up opposition efforts.

Proposition 40 wealth tax details

Proposition 40 is a one-time, 5% levy on the state's more than 200 billionaires, proposed by SEIU United Healthcare Workers West last year to address lost revenue from federal cuts, with 90% of the dollars raised going to healthcare and 10% to food assistance or education-related programs, according to The San Diego Union-Tribune. The tax would apply to individuals with more than $1 billion in net worth who were California residents as of January 1, 2026, with real estate and some pensions and retirement accounts excluded.

Those subject to the tax could pay it in full in 2027 or make annual payments over five years with added interest, the Union-Tribune reported. Proponents claim it will raise $100 billion, while the nonpartisan Legislative Analyst's Office estimates the yield at tens of billions of dollars but said it could reduce ongoing state income tax revenues by less than $1 billion per year if billionaires leave.

The measure's backers say the tax is necessary to prevent hospitals and clinics from closing and low-income residents from losing Medi-Cal coverage, while critics argue it will drive wealthy residents out of the state and inflict long-term damage to the economy, according to the Union-Tribune. California could lose at least $30 billion in annual federal funding as a result of President Donald Trump's spending bill, according to the California Budget and Policy Center.

Billionaire opposition to Proposition 40

Google co-founders Larry Page and Sergey Brin are among the billionaires who moved out of California last year as talk of the wealth tax grew, the Union-Tribune reported. Brin has shelled out more than $100 million to Building a Better California, a newly formed group opposing Proposition 40.

Larsen has been particularly vocal, contributing significantly to campaigns opposing the tax and supporting initiatives that could nullify it, according to Crypto Briefing. The initiative has roiled California politics for months, dividing state leaders and labor unions, the Union-Tribune reported.

Governor Gavin Newsom, who opposes the measure and is eyeing a potential presidential bid, recently called for a national wealth tax instead. "Wealth is movable, and it shops for the state with the lowest taxes," Newsom wrote in a June Substack post, adding that "the fight belongs at the federal level, where this broken system was created in the first place."

Competing measures could void Proposition 40

Even if voters approve Proposition 40, the tax may not take effect. Propositions 41 and 42, which appear on the same ballot, each contain provisions that would void Proposition 40 if either receives more affirmative votes, according to JD Supra.

Proposition 41 would require the state auditor to review proposed special taxes before they go to voters and invalidate taxes that do not comply with the state spending limit, while Proposition 42 would prohibit new state personal property taxes, the Union-Tribune reported. Thad Kousser, a professor of political science at the University of California, San Diego, said the situation poses a "triple challenge" for proponents.

"They don't know where the end zone is," Kousser said. "They're going to have to both make an argument for a wealth tax that has split the progressive coalition, but also make an argument against two other initiatives that may be appealing to voters who see them probably for the first time when they open their ballots."

Supporters and opponents make their case

Dave Regan, the president of SEIU United Healthcare Workers West and the architect of the tax, said in an interview that the tax would prevent a "healthcare catastrophe" in California. "We're either going to watch this train wreck or we're going to pass Proposition 40," he said, calling it "a solution to a problem that was put in all of our laps."

Regan argues the tax will give California five years to figure out a long-term solution for healthcare funding and brushed off claims it would push wealthy residents out, calling that a "disingenuous argument." "A one-time tax creates no incentive for billionaires to leave the state and we felt that was important," Regan said.

Opponents argue the money would only temporarily stem the budgetary bleeding. The No on 40 coalition, which includes the California Medical Association, the California Teachers Association, the California Chamber of Commerce and Planned Parenthood Affiliates of California, positions the initiative on its website as a flawed, reckless tax, the Union-Tribune reported.

The billionaires tax has been endorsed by Rep. Bernie Sanders, the California Democratic Party and the California Federation of Labor Unions. Nvidia CEO Jensen Huang has also voiced his support, recently saying he is "perfectly fine" with having to pay more in taxes; Forbes estimates Huang is worth $198 billion.

What comes next for the Proposition 40 wealth tax

A September poll conducted for The San Diego Union-Tribune found the measure drawing more support than opposition from likely voters statewide, but still shy of a majority, with about 48% of respondents saying they would vote for it. The poll had a credibility interval of 4.6 percentage points.

Just over a month before Election Day, Kousser said he expects the three measures will trigger a massive amount of spending that will blanket the airwaves and fill voters' mailboxes. While the opposition, funded largely by billionaires like Brin, will almost certainly outspend the yes campaign, Kousser said it gives supporters an opportunity to make a David-versus-Goliath argument.

The outcome could reverberate long past Election Day. Many of the progressives who've been uneasy about Prop. 40… my hunch is that if this fails in progressive California, it slows down the momentum for this as a policy nationwide, Kousser said, according to the Union-Tribune.

Conclusion

California voters will decide on November 3, 2026 whether to approve the first-in-the-nation wealth tax, but the fate of Proposition 40 will rest not only on a simple majority but on how much support two competing initiatives receive. With billionaires having raised over $300 million in opposition and market pricing implying a decreased likelihood of passage, observers are watching upcoming polls and public statements from key political figures such as Governor Gavin Newsom, who opposes the measure.

Frequently Asked Questions

What is California Proposition 40?

Proposition 40 is a one-time, 5% wealth tax on California residents with more than $1 billion in net worth as of January 1, 2026. Proposed by SEIU United Healthcare Workers West, it would direct 90% of proceeds to healthcare and 10% to food assistance or education-related programs.

How much have billionaires raised to fight Proposition 40?

Google co-founder Sergey Brin, venture capitalist John Doerr, Ripple co-founder Chris Larsen and others have collectively raised over $300 million in opposition to the measure. Brin alone has contributed more than $100 million to Building a Better California, a newly formed opposition group.

When is the vote on California's Proposition 40 wealth tax?

California voters will decide Proposition 40 on November 3, 2026. Even if approved, the tax may not take effect because Propositions 41 and 42 on the same ballot could void it if either receives more affirmative votes.

How much revenue would the Proposition 40 wealth tax raise?

Proponents claim the tax will raise $100 billion. The nonpartisan Legislative Analyst's Office estimates the yield at tens of billions of dollars, but said it could also reduce ongoing state income tax revenues by less than $1 billion per year if billionaires leave California.

Who supports and who opposes California Proposition 40?

The tax is endorsed by Rep. Bernie Sanders, the California Democratic Party, the California Federation of Labor Unions and Nvidia CEO Jensen Huang. Opponents include Governor Gavin Newsom, the California Chamber of Commerce, the California Medical Association and a billionaire-funded campaign led in part by Sergey Brin.