This briefing reflects reporting and polling available as of Sept. 12, 2026. Candidates, endorsements and polling can change before Election Day on Nov. 3, 2026.
Why This Measure Matters
California’s Proposition 40 would impose a one-time 5% tax on the net worth of the state’s roughly 200 billionaires to fund healthcare, food assistance and education. What makes it unusual is the coalition lined up against it: alongside wealthy opponents, the measure is opposed by Planned Parenthood, the California Medical Association and the California Teachers Association, meaning this is not a simple left-versus-right fight but a genuine split within the state’s progressive and labor movements.
The Measure
Proposition 40 is a combined constitutional amendment and state statute placed on the ballot by the labor union SEIU United Healthcare Workers West, which gathered nearly double the required signatures to qualify it. If approved, California residents worth more than $1 billion as of Jan. 1, 2026 would owe a one-time 5% tax on their net worth, payable over five years if they choose to spread out payments. Real estate, pensions and retirement accounts held directly would generally be excluded. Backers estimate the tax would raise roughly $100 billion over five years from the state’s wealthiest residents; 90% of the revenue would go to state health care programs including Medi-Cal, with the remainder split between food assistance and public education.
Who’s Involved
Supporters include SEIU-UHW, which launched the campaign with an endorsement from Sen. Bernie Sanders, and other labor unions who argue billionaires should contribute more given cuts to federal health and safety-net funding. Opponents include two organized opposition committees: Stop the Squeeze, and Golden State Promise, which reported $10 million from Ripple Labs co-founder Chris Larsen. A separate, competing effort called Building a Better California, backed heavily by Google co-founder Sergey Brin, has qualified rival measures for the same ballot rather than opposing Proposition 40 directly.
Top Issues
Whether the tax is workable. Tax policy researchers, including analysis from the Tax Foundation, have raised questions about the measure’s residency provisions, warning they are vulnerable to legal challenge and could be difficult to enforce if wealthy residents relocate before the tax takes effect.
Whether it actually helps the causes it names. This is the measure’s most distinctive fault line. Planned Parenthood and the California Medical Association have criticized the measure’s connection to health care funding as an inadequate response to the underlying funding cuts it is meant to address, while the California Teachers Association has said the tax would not provide sustainable, ongoing funding for schools.
Whether the state legislature retains control of the money. The measure earmarks how revenue must be spent by category but leaves the state legislature discretion over specific programs and timing within those categories.
Legal durability. Because the tax is one-time and tied to a specific wealth threshold and residency date, several tax law analysts describe it as facing “numerous constitutional challenges,” any one of which could invalidate all or part of it if voters approve it.
Evidence Check
Claim (SEIU-UHW and supporters): the tax would raise about $100 billion over five years for health care, food assistance and education. Check: that figure comes from the campaign’s own economic analysis, prepared by tax law and economics researchers who support the measure; this article could not verify it against an independent, nonpartisan fiscal estimate, and the amount actually collected would depend heavily on how many billionaires remain California residents once the tax takes effect.
Claim (Planned Parenthood and CTA): the measure is a flawed or insufficient response to the funding needs it targets. Check: this is a policy judgment about adequacy and design, not a factual claim about the measure’s mechanics; both groups support the general goal of increased funding for the same programs, making their opposition about structure and reliability rather than the underlying purpose.
Claim: the tax would apply only to about 200 people. Check: this figure, cited in the measure’s own economic analysis, corresponds to independent estimates of the number of California residents with net worth exceeding $1 billion, and is consistent with the measure’s stated $1 billion threshold.
Supporter Voices
The California Teachers Association, opposing the measure despite supporting more school funding generally, said the billionaire tax “will not provide the sustainable and long-lasting” funding schools need. This briefing could not locate comparably sourced quotes from individual voters on either side; coverage of this measure has centered heavily on institutional positions from unions, medical and education groups, and wealthy donors on both sides of the qualifying and opposition campaigns.
How This Measure Is Being Framed
Backers have framed Proposition 40 as a simple fairness question: whether roughly 200 of the wealthiest Californians should contribute more at a moment of state budget strain. Opponents, notably including allies who share the campaign’s underlying goals, have framed it as poorly designed and legally fragile, arguing a one-time, easily avoided tax is the wrong tool even for a cause they support. The involvement of a separate, competing ballot campaign funded by a Google co-founder adds an unusual wrinkle: much of the opposition money in this race comes from interests with a direct financial stake, while some of the most pointed criticism comes from groups with no such stake at all.
Related Links
- 2026 California Proposition 40 – Wikipedia
- California One-Time Wealth Tax for State-Funded Healthcare, Education, and Food Assistance Programs Initiative (2026) – Ballotpedia
- 2026 Billionaire Tax Act: California Wealth Tax Ballot Initiative – Tax Foundation
- What to know about 2026 California ballot propositions – CalMatters
- Proposition 40 – California Legislative Analyst’s Office
Discussion Questions
- Do you think a one-time wealth tax is a fair way to fund health care and education?
- Does it change your view of this measure to know some progressive groups oppose it too?
- Do you find the legal durability concerns or the fairness argument more important in deciding your vote?
- How should voters weigh a policy’s goal against doubts about its specific design?
- What responsibility does a ballot measure’s campaign have to address legal vulnerabilities before voters decide?
- Should wealthy residents relocating to avoid a tax like this factor into how you view the measure?
- Why do you think a wealthy individual would fund a rival ballot measure rather than campaign against this one directly?
- How much should you trust a campaign’s own economic projections versus an independent analysis?
- Should ballot measures earmark exactly how revenue is spent, or leave that to the legislature?
- Imagine you support more health care funding but doubt this measure’s design. How would you vote, and why?
