Measure would fund healthcare for 3.4 million Californians
Tech billionaires have raised more than $340 million to defeat California’s Proposition 40, a one-time 5% wealth tax heading to voters in early November. With the election less than a month away, those funds are being spent at a stepped-up pace: during the first 19 days of September, according to the most recent campaign filings, the opposition campaign plowed through at least $21.2 million to fight the billionaire tax — surpassing $1 million per day. Voters are being inundated with robotexts, mailers, and advertisements that warn a tax on billionaires would “expose all Californians to higher taxes,” as one ad reads. State campaign finance disclosures show Google co-founder Sergey Brin contributing at least $102 million — the biggest single donation — and former Google CEO Eric Schmidt giving more than $42 million. A super PAC called Building a Better California has provided most of the opposition committees’ funding.
Proposition 40, the ballot measure at the center of the fight, would impose a one-time 5% tax on the state’s billionaires, directing most of its proceeds to healthcare programs, with smaller allocations to education and food assistance. The Service Employees International Union-United Healthcare Workers West (SEIU-UHW) proposed the measure last year, citing the need to preserve coverage for 3.4 million Californians after federal healthcare cuts under President Donald Trump’s One Big Beautiful Bill Act.
The measure has divided California Democrats, with some giving enthusiastic support and others rejecting the proposal because it is a one-time levy whose bulk would fund only certain healthcare programs. State unions and progressive politicians including Vermont Sen. Bernie Sanders and California Rep. Ro Khanna have endorsed it. Gov. Gavin Newsom, Democratic gubernatorial candidate Xavier Becerra, Republican candidate Steve Hilton, former U.S. Rep. Katie Porter, and Planned Parenthood Affiliates of California have publicly opposed the tax. Among the measure’s fiercest critics, however, are the tech billionaires it would most directly apply to.
The donors to the “no” campaign read as a roster of Silicon Valley’s wealthiest figures. Beyond Brin and Schmidt, those named in campaign filings include Palantir co-founder Peter Thiel, DoorDash CEO Tony Xu, Stripe CEO Patrick Collison, crypto magnate Chris Larsen, and several prominent venture capitalists.
The “yes” campaign has raised a total just shy of $33 million, mostly from the SEIU-UHW union sponsoring the measure. The three committees opposing Proposition 40 and supporting the two companion ballot measures have received more than $297.8 million combined since July, most of that from a super PAC called Building a Better California.
Proponents and opponents alike are casting the billionaire tax as a potential first step toward wealth taxes in more states. While those against the measure see it as populist contagion, those in favor connect it to the top issue of the midterms — affordability. With California having more billionaires than any other state, Proposition 40 is seen as setting the stage for more referendums on wealth inequality throughout the country.
“There’s a lot of volatility among the electorate surrounding a pushback against Marie Antoinette and her tech friends,” said David McCuan, a political science professor at Sonoma State University who studies ballot measures. “And that’s what the ‘yes’ forces are relying on.”
Recent polling on Proposition 40 shows that it is favored to pass, but the measure’s lead has shrunk over the last few weeks as the opposition campaign has increased spending. A late-September poll by the University of California shows 45% of voters likely to vote yes on the tax with 42% voting no — a 3-percentage-point margin. Just a month earlier, the proposal enjoyed a 7-percentage-point lead.
Opponents of the wealth tax have also explicitly targeted the Latino community, placing ads, articles, and op-eds in Spanish-language news outlets throughout the state. One article in San Diego’s El Latino carried the headline: “No a la Proposición 40: Una Buena Idea, Mal Construida” (“No on Proposition 40: A good idea, poorly executed”).
Voters will also see Propositions 41 and 42 on the November ballot. Proposition 41 directly targets the billionaire tax, while Proposition 42 is more of a general proposal to protect individuals from certain new taxes. If either measure receives more “yes” votes than Proposition 40, they will stop the billionaire tax from taking effect — even if it passes. Proposition 40’s opponents successfully placed the two companion measures on the November ballot, complicating the wealth tax’s path to implementation.
“Props 41 and 42 have poison pills in them to destroy 40,” said McCuan. “And when voters are confused, when they are uncertain … it’s much easier to get a no vote.”
The opposition’s public messaging avoids mentioning billionaires. Ads aired across television, digital, and streaming platforms feature California Medical Association president René Bravo in a white lab coat warning that the tax would hurt “doctors, teachers, small businesses, working families and public safety.” The campaign has debuted similar ads saying teachers, carpenters, and firefighters also oppose the wealth tax, calling it “a dangerous experiment.” One advertisement claims the wealth tax would “expose all Californians to higher taxes.” The “no on Proposition 40” campaign has labeled the measure “an everyone tax.”
Likewise, the campaigns for the two measures that would pre-empt the billionaire tax argue these proposals promote transparency and have the backing of small businesses and taxpayers. One of the measures says its coalition includes retirees, blue-collar workers, seniors, and veterans.
The three campaigns against the wealth tax draw nearly all of their funding from super PACs loaded with Silicon Valley money, according to campaign finance filings. The billionaires have found themselves in alliance with several healthcare, education, construction, and public safety unions and associations. Newsom has decried the billionaire tax, as have gubernatorial candidates Becerra and Hilton. Porter, a former Democratic congresswoman known for taking corporate executives to task, has become one of the main faces of the opposition campaign — writing op-eds, speaking at rallies, and being quoted in ads and mailers.
The three campaigns are spending much of their fortunes on an army of consultants tasked with everything from lobbying politicians to working on media strategy. The consultants include the Republican-leaning law firm Nielsen Merksamer, known for fighting on behalf of tobacco companies, and the political consultancy PCI Campaigns, known for battling propositions that sought to repeal the death penalty and require condom use in pornographic films.
Planned Parenthood Affiliates of California is also listed as a paid contractor in campaign filings and has been one of the “no” campaign’s most vocal endorsers.
State filings show that the campaigns donated tens of thousands to the California Democratic Party, along with the Democratic parties of San Diego, Orange County, and Los Angeles County. Despite the donations, all of these Democratic parties have backed the billionaire tax, urging a yes vote on Proposition 40.
When asked about the “no on Prop 40” campaign’s spending strategy and the donations it has received from super PACs, a spokesperson for the campaign emailed a comment from Bravo: “The more Californians learn, the more they see Prop. 40 for what it is — a harmful tax scheme that permanently damages the state’s budget and economy with zero accountability or safeguards to ensure funding actually improves care or lowers costs for patients.”
Brin and Planned Parenthood Affiliates of California did not return requests for comment. The Building a Better California super PAC declined to comment.
Last week, Sanders, the progressive senator from Vermont, traveled to California to stump for Proposition 40 alongside state politicians. At a rally in downtown Los Angeles, the longtime advocate of wealth taxes announced to a crowd of supporters that the measure was “the most important ballot initiative in the country.”
“The whole country, and frankly people from around the world, are paying attention to what is happening here,” Sanders said to applause. “It is not easy running a campaign where you’re going to be greatly outspent. But that is what you are doing, and the entire country is proud.”
The “yes” campaign has garnered momentum through its partnerships with unions, community leaders, and progressive politicians, including Khanna, a Democratic congressman who represents the district that includes Silicon Valley; the California Federation of Labor Unions AFL-CIO; the California Teamsters union; and the state’s Democratic Party. Besides the SEIU-UHW, one of the campaign’s biggest donors is Saikat Chakrabarti, a former tech engineer who ran for Congress earlier this year but lost in the primary.
“A few controversial billionaires like Sergey Brin would rather spend millions to fund shady opposition campaigns than simply pay their fair share in taxes so millions of their fellow Californians don’t lose their healthcare,” said Debru Carthan, a spokesperson for the “yes” campaign and a vice president of SEIU-UHW. “No amount of billionaire spending is going to intimidate us or turn us back.”
Instead of relying on more expensive traditional media, the “yes” campaign has turned to Instagram, Snapchat, and YouTube to create viral moments and target younger audiences. Campaign finance disclosures show campaign expenditures have gone to consultants, mailers, and social media ads.
“Dolly Parton could have died a billionaire and she didn’t,” an unnamed influencer said in a “yes on Prop 40” post last month. “And the one reason that she didn’t is that she spent decades of her life giving away her money to charity and to philanthropy … There’s a really simple question that I want to ask the billionaires of California: how much is enough?”
The “no on Prop 40” campaign has also paid for ads on Google, Instagram, Yahoo, X, and Taboola, according to campaign filings. It has additionally paid $3,000 for its Instagram posts to be amplified — a practice that gives an inorganic boost to social media.
“Billionaires are pouring hundreds of millions into deceptive commercials to confuse voters about Prop 40 because the truth is, they know that taxing the rich is popular,” said Lorena Gonzalez, president of the California Federation of Labor Unions. “We cannot let them buy our elections and choose who gets to live or die.”
McCuan said the stakes extend beyond California. “That is about testing the broader issue of wealth inequality and affordability in a wide-open presidential election in 2028,” McCuan said. “And if you’re a zillionaire or on the no side, you want to nip this thing in the bud so it doesn’t go to other places.”