California's billionaire tax is dead. Democrats are already planning the next fight.

California's proposed one-time tax on billionaires is dead — killed by a $378.4 million opposition campaign that outspent supporters by more than ten to one. With 52.8% of voters opposed and 47.2% in favor, the Associated Press declared the race called on Monday. But the coalition of Silicon Valley executives who bankrolled the defeat may have bought themselves only a temporary reprieve: incoming Democratic majorities in Congress are already signaling they intend to take the fight national.

Under Proposition 40, California residents with a net worth exceeding $1 billion as of January 1, 2026, would have faced a one-time 5% levy on financial assets, business stakes, art, collectibles, and intellectual property — though real estate, pensions, and retirement accounts would have been excluded. The measure's backers, headed by the Service Employees International Union-United Healthcare Workers West, contended it was necessary to offset healthcare funding gaps caused by federal spending reductions in President Donald Trump's tax and spending legislation. They estimated it could raise over $100 billion, with roughly 90% directed toward healthcare and the remainder toward education and food assistance. An October working paper from Stanford economists published through the National Bureau of Economic Research cautioned that the initial tax event might generate roughly $30 billion before triggering executive departures — and could leave California $38.9 billion worse off over time.

Google co-founder Sergey Brin spearheaded the opposition, pouring approximately $102 million into Building a Better California, a political committee he founded in January that served as the primary vehicle against the measure. Having moved to Nevada in December 2025, Brin's fortune — pegged at $231 billion by Bloomberg — would likely have fallen outside the tax's reach. Former Google CEO Eric Schmidt contributed $40.2 million. Among those who also gave millions were DoorDash CEO Tony Xu, Stripe co-founder Patrick Collison, venture capitalist John Doerr, cryptocurrency entrepreneur Chris Larsen, and former Sequoia Capital partner Michael Moritz. CalMatters reported that wealthy opponents combined to put $378.4 million into efforts against the tax and related countermeasures.

The opposition strategy went beyond defeating Proposition 40 directly. Building a Better California also spent heavily to advance Propositions 41 and 42 — two countermeasures designed to undercut the wealth tax even if it passed. Proposition 41 would have required pre-election audits for initiatives proposing special taxes and prohibited new tax revenue from being exempted from state spending limits. Proposition 42 would have prohibited taxes on personal savings, assets, and retirement holdings — directly countering Proposition 40. The Legislative Analyst's Office noted that if either countermeasure drew more yes votes than Proposition 40, the wealth tax could be blocked even with voter approval. The AP reported that Proposition 42 did pass, meaning Proposition 40 would have been stopped regardless of its own vote count.

The geographic fault lines of the vote were striking, according to Business Insider. Progressive urban strongholds — Los Angeles, San Francisco, and Alameda County — favored the measure with slim majorities. Across California's Central Valley and desert regions, however, many majority-Hispanic agricultural communities rejected it by double-digit margins. Tech-heavy Bay Area counties representing Palo Alto, Cupertino, and the Peninsula cities came out firmly against the tax. The measure also split traditional political alliances: Vermont Sen. Bernie Sanders backed the billionaire tax, while California's Democratic Gov. Gavin Newsom came out against it, contending that a state-level wealth tax would drive wealthy residents and businesses to leave California.

Here is what I support: A national billionaires' tax. A true minimum tax on billionaires — a modern Buffett Rule — that ensures the people at the very top pay at least the tax rate their own workers pay.— Gavin Newsom, California Governor

Newsom's position points to where the real battle may now be headed. Democrats are set to take control of both the U.S. House and Senate in January, and several incoming members have been explicit about their intentions. In a Wednesday morning NPR interview, Michigan senator-elect Abdul El-Sayed indicated billionaires should expect to be paying higher taxes. Henrietta Treyz, co-founder and director of economic policy at Veda Partners, said that higher income taxes on billionaires — and possibly a dedicated bracket for trillionaires — are likely to appear in legislation Democrats could put together next year. She noted the same bill would likely be stuffed with affordability provisions designed to draw a veto from President Trump, setting up campaign fodder for Democrats heading into the 2028 presidential election.

The billionaire tax debate at a federal level is coming, even if it fails at the state level.— Henrietta Treyz, co-founder and director of economic policy, Veda Partners

The timing matters beyond the next election cycle. According to Morningstar, a number of significant tax breaks in the Republican tax law are due to lapse in 2028 and 2029, making those years a critical juncture for any wider debate over how the wealthiest Americans are taxed. In a Wednesday statement, Sen. Ron Wyden of Oregon, the top Democrat on the Senate Finance Committee, said the committee would "redouble its efforts to ensure billionaires pay their fair share and hold tax cheats accountable."

Other states offered a mixed picture on election night. Washington state voters declined to repeal a 9.9% income tax on millionaires, with no votes running ahead by roughly 58% to 42%. Colorado's Amendment 87, which would swap the state's flat income tax for a progressive structure — raising rates on households earning more than $500,000 while lowering them for most residents — held a narrow lead. Meanwhile, a separate California ballot measure looked set to preserve the state's higher income-tax rates for its wealthiest residents, even as voters turned down the one-time wealth tax.

The sheer cost of the California fight is itself a landmark. David McCuan, a Sonoma State University professor who monitors spending on state and local elections, put total outlays on Proposition 40 — from both sides — at more than $500 million, with the figure potentially climbing toward $650 million. Politico reported that more than 70 current and former California billionaires poured a record $612 million into state elections this cycle overall, with at least 30 billionaires directing more than $293 million specifically toward the wealth tax fight.

This makes Prop. 40, in real dollar terms, the most expensive ballot measure ever, in the most expensive midterms ever.— David McCuan, professor, Sonoma State University

For supporters, the defeat is not necessarily the end. Andrew Lokay, a senior research analyst at Beacon Policy Advisors, contended that even a failed Proposition 40 moved the needle: "Now that it's been proposed, that takes the concept from the theoretical to a reality." United Healthcare Workers West president Dave Regan took the stage at a Tuesday night press conference to pledge that the effort would continue, saying, "It's not enough to try once when you deal with something like this."

The backdrop to all of this is widening wealth inequality. Federal Reserve data cited by Morningstar shows the gap has been growing, and the 2025 Republican tax law kept most income-tax rates — including the top rate — from increasing. That combination is what supporters of wealth taxes point to as the underlying pressure that will keep the issue alive regardless of what happened in California on Tuesday.

Why it matters — California's defeat of Proposition 40 is the opening round of what analysts and incoming Democratic lawmakers say will be a sustained national fight over whether — and how — the United States taxes extreme wealth, with federal legislation expected as early as next year and major tax-law expirations arriving in 2028.

Sources differ on Revenue Proposition 40 would have generated: Over $100 billion over several years (businessinsider.com (citing Prop. 40 backers)) vs 'Tens of billions' of dollars (yahoo.com (citing Legislative Analyst's Office)) vs ~$30 billion initially, then a net loss of $38.9 billion over time after executive departures (businessinsider.com (citing Stanford/NBER working paper))

Reported by thewealthadvisor.com, businessinsider.com, yahoo.com, morningstar.com