The California billionaire tax ballot measure is set for a November 3, 2026, vote after last-ditch negotiations between Governor Gavin Newsom and the union backing the initiative collapsed before the 25 June deadline. The initiative, formally titled the One-Time Wealth Tax for State-Funded Health Care Programs Initiative, qualified for the ballot on 17 June after the California secretary of state’s office verified the required petition signatures, according to CalMatters.
The measure would impose a 5% one-time levy on the net worth of California’s 200-plus billionaires, the largest concentration in any US state. Most of the projected $100 billion in revenue is earmarked to offset federal cuts to healthcare for low-income residents, with additional funds directed to food assistance and education programmes, according to Fortune.
The California Billionaire Tax Ballot: What the Measure Actually Requires
The union behind the initiative is the Service Employees International Union-United Healthcare Workers West, which argues California needs the revenue to rescue its healthcare system from cuts in the Trump administration’s tax reform package, the ‘One Big Beautiful Bill Act.’ The day after the measure qualified, the union offered to drop the 5% proposal if Newsom would back a 2% levy instead, a compromise that would have required the Legislature to act before the deadline. No deal was reached.
The mechanics are more complex than the headline rate suggests. Under the initiative, residency eligibility is determined as of 1 January 2026, while net worth is calculated as of 31 December 2026. The tax covers shares of capital stock, bonds and other debt instruments, real estate held through a business, and any legal or equitable interest. It also applies to certain trusts, defined as any non-grantor, non-tax-exempt trust to which a qualifying billionaire has transferred property, according to Baker Botts.
Proponents say the bill is not a pay-it-all-now demand: the tax can be settled upfront or spread across five years in annual instalments of 1% of the assessed net worth each year, with deferral charges applied, according to the Institute on Taxation and Economic Policy (ITEP).
Advisors Say Wealthy Clients Are Already Voting With Their Feet
Advisors to the ultra-wealthy say many of their clients moved before the residency cut-off date. David Lesperance, a lawyer who advises billionaires on immigration, citizenship, and taxes, told Business Insider he had seven clients leave California before 1 January 2026. He said those clients ‘always assumed it wasn’t one time, it was the first time,’ meaning even those already liable may not remain for a potential second round.
Michael Cole, managing partner at R360, an invite-only club for ultra-high-net-worth families, said the measure could be the final push for those who have not yet left. He called it ‘another example of people feeling like California is at the leading edge of undue tax onto those that succeed.’ Cole pointed to a specific practical problem for founders: a person with a net worth above $1 billion held almost entirely in illiquid private company stock could face a cash bill of around $50 million before ever realising that value. ‘Have to pay $50 million of cash when the value of the company has never been realized yet,’ he said.
ITEP estimates that, including all taxes at all levels of government, California billionaires paid only 24% of their true economic income in taxes in the years 2018–20, compared with a US-wide average of 30% during the same period.
Legal challenges are widely expected if the measure passes. Baker Botts has identified a potential constitutional challenge on the grounds that the retroactive application of the tax to residents as of 1 January 2026 may violate the Due Process Clause of both the United States and California constitutions. Kristin Yokomoto, a private wealth attorney at FBT Gibbons, has flagged additional questions around the nature of taxing net worth rather than income, treatment of out-of-state assets, and complications such as divorces that push a couple below the $1 billion threshold.
Newsom, widely regarded as a 2028 presidential contender, has responded by calling instead for a federal wealth tax, one that would be harder to escape by relocating. According to PBS NewsHour, he also called for new inheritance tax rules, warning that the transfer of wealth among the ultra-wealthy would ‘lock in a permanent American aristocracy of inherited wealth,’ and for raising corporate tax rates to pre-Trump first-term levels.
Lesperance said some of his clients are funding lobbyists to find a tax framework that satisfies California without triggering further departures, quoting the old line: ‘The art of taxation is plucking the golden geese with the least amount of hissing.’ Whether California’s ballot box or its courtrooms resolve the matter first may define the outcome.