Proposition 40 would impose a one-time 5% tax on the net worth of California residents and certain trusts whose assets exceed $1 billion, proponents say the levy would target roughly 200–250 people if voters approve it on Nov. 3.
The initiative sets the $1 billion threshold and a flat 5% rate, and the official voter guide describes the design as applying to individuals and some trusts with valuation rules for private assets, according to reporting and the ballot text.
Under the proposal the tax would apply retroactively to people who were California residents on Jan. 1, 2026, a detail noted in coverage that also says a handful of billionaires have already changed residency plans ahead of that date.
Supporters say most revenue would be spent on healthcare: KQED’s voter guide reports that 90% of proceeds are earmarked for healthcare services, with the remainder for food assistance and education-related programs.
Backers and academic allies have estimated the initiative could raise very large sums — some proponents say roughly $100 billion — while nonpartisan summaries and other outlets describe the likely yield as “tens of billions” over a limited period rather than an ongoing revenue stream.
Opponents warn the measure could prompt wealthy residents to leave and that it is a one-time levy while federal funding cuts are permanent; reporting shows major donations from wealthy individuals and organizations funding anti-Prop 40 campaigns.
Legal and valuation questions are central to the debate: analysts quoted in news coverage say valuing stakes in private companies and other illiquid assets is complex, and the initiative includes formulas and possible deferrals for hard-to-value holdings.
The contest has drawn prominent endorsements and opposition — from politicians and unions on both sides — and polling cited by outlets showed the measure close in October, with support slipping toward a narrow margin in some surveys.
For voters and businesses weighing the measure, the stakes are twofold: whether a one-time wealth levy is an appropriate emergency source to backfill projected health-care funding gaps, and whether it would prompt behavioral responses that reduce longer-term tax receipts.
Sources
- BBC — background on the scope of Prop 40, the Jan. 1, 2026 residency cutoff, estimates of roughly 200+ billionaires affected and reporting on wealthy residents leaving.
- KQED — voter guide text describing the one-time 5% tax, the $1 billion threshold, and that 90% of revenue would go to healthcare services.
- ECIKS — explainer on how the levy would work, revenue estimates and discussion of legal and valuation issues.
