California's 5% Billionaire Tax: What November Voters Will Decide
California voters will decide in November 2026 whether to impose a one-time tax of up to 5% on the state's billionaires. The proposal, Proposition 40 in the 2026 election, would apply to taxpayers and trusts with covered assets valued over $1 billion who were residents of California on January 1, 2026. CalMatters
The levy is written as an initiative constitutional amendment and statute titled "Imposes One-Time Tax on Certain Individuals and Trusts." California Secretary of State Shirley N. Weber announced the measure as eligible for the November 2026 General Election ballot in a June 17, 2026 release. California Secretary of State
Proposition 40 would create the 2026 Billionaire Tax Reserve Fund, where all taxes, interest and penalties collected under the initiative would be deposited. Ballotpedia An estimated 200 to 250 billionaires would be subject to the 5% tax. Reuters
Governor Gavin Newsom opposes Proposition 40 and backs Proposition 42. CalMatters Proposition 42 would nullify the billionaire tax and ban future wealth taxes in California. A wealth tax is a levy on net worth, what you own, rather than yearly income. In operative terms, Proposition 42 would nullify taxes enacted after January 1, 2026.
A Citrin-POLITICO poll found the proposed billionaire tax was short of majority support as Californians began casting ballots. POLITICO
MarketWatch on Oct. 20, 2026 published "It's not just California's billionaire tax. Wealth is on the ballot in the midterm elections." MarketWatch Voters in Washington and Colorado are considering 2026 ballot measures that would raise taxes on millionaires and billionaires. Barron's California's proposal is the first U.S. billionaire tax to be put to a vote. AFP
The broader context here is tax design colliding with ballot mechanics, and it matters for household budgets and market expectations alike. For savers and borrowers, the direct effect is less the billionaires' bill than what the outcome signals for state finances and ballot-led tax policy. The operative variables are the Jan. 1, 2026 residency test, coverage of both individuals and trusts, and the one-time rate of up to 5% on covered assets above $1 billion. A single assessment date plus trust inclusion narrows deferral and splitting strategies that would matter more under an annual tax, while concentrating valuation, liquidity and enforcement risk in one event. The dedicated reserve fund structure also separates collection from general-fund appropriation, which matters for credit and cash-flow modeling if the tax survives legal challenge. The paired-measure structure creates a binary legal overlay. Proposition 40 would impose liability anchored to a past residency date, while Proposition 42 would void taxes enacted after that same Jan. 1, 2026 threshold. That leaves investors, advisors and taxable estates weighing not only voter approval of the levy but approval and ordering of a nullifying amendment. The early polling shortfall does not resolve that sequencing risk. With similar millionaire and billionaire questions before voters in Washington and Colorado, multi-state filers face parallel residency, sourcing and trust-situs questions rather than a single California event.
