California voters are deciding on Tuesday, November 3, 2026, whether to impose a one-time tax on the state's billionaires, in one of the most closely watched ballot measures of the midterm elections. Proposition 40, known as the 2026 Billionaire Tax Act, would levy a 5% tax on the net worth of California residents worth $1 billion or more, a proposal that supporters say could raise tens of billions of dollars for health care, education and food assistance, and that opponents warn could drive wealthy residents and investment out of the state.

The measure arrives on a ballot already crowded with high-stakes contests and competing propositions, and its fate may not be settled by a simple yes or no. Even if Proposition 40 wins a majority, it could still be cancelled if either of two rival measures, Proposition 41 or Proposition 42, wins more yes votes. That unusual twist means California voters are not merely deciding whether billionaires should pay more; they are choosing between competing visions of how the state should tax wealth, limit spending and shape its fiscal future.

Key Points

• Proposition 40 would impose a one-time 5% tax on California residents worth $1 billion or more, based on residency on January 1, 2026, and net worth measured on December 31, 2026.
• About 200 people would be affected, with the ten wealthiest facing roughly $31.5 billion combined, including about $10.9 billion for Mark Zuckerberg and $9.5 billion for Jensen Huang.
• The Legislative Analyst's Office estimates tens of billions of dollars over several years, with 90% going to health care and the rest to education, food assistance and administration.
• Taxpayers could pay with their 2026 return in 2027 or in five annual instalments, with a 7.5% deferral charge for spreading payments.
• Even a yes vote may not take effect: rival Propositions 41 and 42 would cancel Proposition 40 if either wins more yes votes.

What Happened

California voters went to the polls on Tuesday, November 3, 2026, to decide Proposition 40 alongside federal, state and local races in the midterm elections. The measure, formally the 2026 Billionaire Tax Act, asks voters to approve a one-time levy on extreme wealth held by people who were California residents on January 1, 2026. Net worth would be measured on December 31, 2026, capturing stocks, bonds, cash and business interests, while real estate and most retirement accounts would generally be excluded.

The tax would be payable with the 2026 tax return in 2027, or in five annual instalments for those who choose to spread the cost, subject to a 7.5% deferral charge. The Legislative Analyst's Office, the state's nonpartisan fiscal adviser, estimates the measure would raise tens of billions of dollars over several years. Under the measure's allocation, 90% of the revenue would go to health care, with the remainder directed to education, food assistance and administration.

Polling before Election Day suggested a close and shifting contest. A UC Berkeley and Los Angeles Times poll released on October 29 found 50% opposed and 42% in favour, down from a narrow majority in favour six weeks earlier. That movement underscored how much the campaign's final weeks, and the presence of competing measures on the same ballot, could matter to the outcome.

Background and Context

California has long been home to an outsized share of America's wealth, from Silicon Valley technology fortunes to entertainment, real estate and venture capital. It has also faced persistent pressure on health care costs, school funding and food assistance, pressures that supporters of Proposition 40 argue make a one-time levy on billionaire wealth both fair and practical. The measure's backers present it as a targeted charge on fortunes that, in their view, have grown far faster than the public services on which ordinary Californians depend.

California Proposition 40: How the Billionaire Tax Would Work

Under Proposition 40, the tax would apply only to residents worth at least $1 billion. The 5% rate would be applied once to net worth above that threshold as measured at the end of 2026, rather than as an annual levy. Stocks, bonds, cash and business interests would be included in the calculation, while real estate and most retirement accounts would generally be excluded, a distinction that matters for how different fortunes would be assessed.

Reactions and the Campaign Divide

The campaign has split California's political landscape in unusual ways. Supporters include Senator Bernie Sanders, who has long advocated higher taxes on very large fortunes, and who frames the measure as a question of fairness. For supporters, the argument is straightforward: a small number of people with extraordinary wealth can contribute a one-time share toward health care, schools and food assistance without affecting the vast majority of Californians.

Why It Matters

Proposition 40 matters first for California's budget. Tens of billions of dollars, even spread over several years, would be a major infusion for health care, which would receive 90% of the revenue under the measure. In a state where health care costs and access remain pressing concerns, that funding could affect hospitals, clinics, coverage and public health programmes, though the precise uses would depend on later legislative and administrative decisions.

What Happens Next

Results will be counted on election night and in the days that follow, with California's large vote-by-mail system meaning that close contests can take time to resolve. The first question will be whether Proposition 40 itself wins a majority. The second, equally important, will be how Propositions 41 and 42 perform. Proposition 41 concerns spending limits and Proposition 42 would ban new personal-property taxes, and either winning more yes votes than Proposition 40 would cancel it, even if Proposition 40 also passes.

Frequently Asked Questions

What is California Proposition 40? It is the 2026 Billionaire Tax Act, a ballot measure proposing a one-time 5% tax on California residents worth $1 billion or more.

Who would pay the tax? About 200 people, based on residency on January 1, 2026, and net worth measured on December 31, 2026, covering stocks, bonds, cash and business interests, with real estate and most retirement accounts generally excluded.

How much would it raise? The Legislative Analyst's Office estimates tens of billions of dollars over several years, with 90% for health care and the rest for education, food assistance and administration.

When would it be paid? With the 2026 return in 2027, or in five annual instalments with a 7.5% deferral charge.

Could Proposition 40 pass and still not take effect? Yes. Rival Propositions 41 and 42 would cancel it if either wins more yes votes than Proposition 40.

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