2026 California Proposition 40

The story so far

As of August 3, 2026

California’s Proposition 40 is a statewide ballot fight over whether to impose a one-time 5% tax on the wealth of Californians worth at least $1 billion. Backed by progressive advocates and opposed by many business-aligned groups and wealthy residents, it is a high-profile test of taxing extreme wealth by popular vote in the country’s largest state. The stakes include significant potential revenue for health care and education and a precedent that could shape national tax debates.

Supporters moved the measure onto the political stage by turning in 1.5 million voter signatures, well above the roughly 875,000 needed to qualify for the November ballot. That show of strength shifted the campaign from qualification to coalition-building and forced an internal debate among Democrats over whether to give the measure official backing.

That debate culminated in a narrow California Democratic Party endorsement, giving Proposition 40 the imprimatur of the state’s dominant political organization heading into the fall campaign. The close vote underscored divisions, with the party breaking from Gov. Gavin Newsom and Attorney General Xavier Becerra, who opposed the measure. After pushback, a major labor backer offered to scale back the proposal, signaling that design details are the fault line for wavering Democrats even as the party machinery now lines up behind Yes.

What matters now is credibility on execution. The fight centers on how to value illiquid assets for a one-time assessment, what revenue the levy would actually produce, and whether a state wealth tax can withstand court scrutiny without triggering investor flight. Supporters cast it as a targeted fairness measure affecting only a tiny slice of residents; opponents are mounting a well-funded campaign, with billionaires spending millions to defeat it. The next phase is the November vote, as official guides and advertising land and both sides press their legal and economic cases to a broad electorate.