California voters will face a proposed one-time wealth tax on the state's billionaires when they head to the polls in November. The measure, known as Proposition 40 or the 2026 Billionaire Tax Act, would impose a 5 percent levy on the net worth of residents worth more than $1 billion as of January 1, 2026, with valuation set at the end of that year.

The tax would apply to worldwide assets excluding primary real estate holdings, though business-owned real estate remains taxable. Proponents estimate it would generate about $100 billion over five years from roughly 250 affected taxpayers, with funds directed primarily to healthcare programs, K-14 education, and food assistance. Taxpayers could spread payments over five annual installments subject to a deferral charge.

The initiative qualified for the ballot after organizers collected sufficient signatures, according to state officials. It emerged amid concerns over reduced federal funding for state programs. A healthcare workers union led the effort, framing the tax as a way for billionaires to contribute more to sustain essential services.

Governor Gavin Newsom has urged voters to reject the measure, warning it could accelerate the departure of wealthy residents and businesses from the state. Some high-net-worth individuals have already relocated in anticipation of the tax. Critics argue the retroactive elements and broad definition of assets could create liquidity issues and discourage investment.

The proposal has drawn support from labor unions and certain progressive figures but faces skepticism from moderate Democrats. Competing ballot measures on the same November ballot may further complicate its prospects. Legal challenges are also expected if it passes, given questions over its constitutionality and enforcement.

From a policy standpoint, the tax represents an aggressive attempt to target accumulated wealth rather than income. Historical evidence from other jurisdictions shows wealth taxes often lead to capital flight and administrative burdens without delivering sustained revenue gains. California's already high tax burden and regulatory environment amplify these risks at a time when the state faces ongoing fiscal pressures and population outflows.

With the election roughly seven weeks away, campaigns on both sides are intensifying. The outcome will test whether voters prioritize short-term revenue extraction over long-term economic competitiveness.