Here's the lowdown
Proposition 40 would charge a one-time 5% tax on the wealth of billionaires who lived in California at the start of 2026.
The measure had 45% support with 60% of the estimated vote counted, below the majority needed to pass.
Even a late comeback may not be enough because Proposition 40 must also finish with more yes votes than rival Proposition 42.
A tax built for a tiny group became a giant fight
California asked voters to approve something no state had tried before: a one-time tax on billionaire wealth.
Proposition 40 would apply a 5% charge to people who were billionaires and California residents at the start of 2026. Most of the money would go toward health care.
The pitch was simple. Tax a very small group once, then use the proceeds to soften federal health care cuts. The execution was not simple at all.
With 60% of the estimated vote counted, the measure had 45% support. It needs more than half to pass.
The opposition spent like the tax was personal
Opponents raised more than $300 million. A group backed by Google cofounder Sergey Brin and other wealthy donors led the campaign against the measure.
That money paid for a broad argument: taxing wealth instead of annual income could drive capital and founders out of California, invite legal fights, and give the state a hard-to-value tax base.
The opposition was not limited to billionaires. Governor Gavin Newsom and Planned Parenthood affiliates in California also opposed the measure, creating an unusual coalition around a tax aimed at the ultrawealthy.
Supporters saw the same facts differently. They argued California needed a large, concentrated source of revenue to protect hospitals and health coverage.
Proposition 42 is the second lock on the door
Proposition 40 has to win its own vote. It also has to beat a competing measure.
Proposition 42 was designed to block the wealth tax. It had 54% support in the reported count.
For the 5% tax to take effect, Proposition 40 must clear 50% and receive more yes votes than Proposition 42. That creates a two-part test, not a normal pass-or-fail ballot question.
Advisers should keep that structure clear when talking with affected clients. A late rise above 50% would not automatically make the tax effective.
Mail ballots leave room, but not certainty
California counts a large number of mail ballots. Valid ballots can arrive up to a week after election day if they were mailed on time.
That means the current margin is not a certified result. Late ballots can move percentages, especially in a statewide contest with a huge spending campaign.
Still, a five-point deficit plus the competing measure is a steep climb. The responsible planning stance is to monitor the count without treating either defeat or enactment as final.
The idea is not going away
Supporters are already talking about trying again in 2028 if Proposition 40 fails.
That matters beyond California. Advocates hoped the state could provide a model for taxing extreme wealth elsewhere. A defeat would slow that strategy, but it would not end the political pressure behind it.
For tax professionals, the practical lesson is narrower. Wealth-tax proposals can turn residency dates, asset valuation, liquidity, and competing ballot language into planning issues long before a tax becomes law.
California voters may reject this version. The argument over how to tax billionaires is still very much alive.
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