California's 5% billionaire tax faces poison-pill ballot challenge

California voters will decide in November whether to impose a one-time 5% wealth tax on the state's 259 billionaires, but two counter-initiatives funded by tech billionaires could void the measure even if it wins a majority.

"Passing this ballot initiative will ensure that millions of working-class and middle-class Californians won't lose their healthcare," Ro Khanna, the U.S. Representative from California and a leading Prop. 40 supporter, said.

Prop. 40 would tax residents with assets above $1 billion, excluding real estate and certain retirement accounts. The measure could raise tens of billions, with 90 percent going to health coverage programs and 10 percent to education and food assistance. Recent polling shows 48 percent support versus 41 percent opposition.

The stakes extend beyond the ballot box. If Prop. 40 passes, California could collect tens of billions from the wealth tax, but the Legislative Analyst's Office warns the long-term fiscal outlook is uncertain. Billionaires including Mark Cuban have threatened to leave the state, and Google co-founder Sergey Brin has poured millions into the opposition PAC.

Building a Better California, a PAC formed this year to oppose Prop. 40, has backed two counter-initiatives — Propositions 41 and 42 — that contain conflict clauses designed to void Prop. 40 if either receives more votes. Prop. 41 prohibits new state taxes that exclude revenues from the state spending limit approved by voters in 1979, while Prop. 42 prohibits new state taxes on personal property, including business interests, intellectual property, and financial assets. Neither is explicitly labeled as an anti-billionaire-tax measure, but their conflict clauses make them effective poison pills.

Billionaire flight risk shapes the debate

Mark Cuban has been among the most vocal critics. "People don't realize that a billionaire doesn't mean you have a billion dollars in liquid assets," Cuban said on the Pivot podcast. "If you have a company that's valued at $10 billion, and you have three founders that each own 10%, they're billionaires by the state of California's definition. The chances of them having $50 million in cash are zero."

Cuban said he would leave California before Prop. 40 took effect if it passed, and that he would advise portfolio companies to relocate. "But you can bet if I'm investing in a multi billion dollar startup, I'm asking them to move from California first," he wrote on X.

The political alignment is sharply split. A UC Berkeley poll found 80 percent of California Republicans oppose Prop. 40, while 70 percent of registered Democrats support it. Gov. Gavin Newsom and Democratic gubernatorial candidate Xavier Becerra oppose the measure, arguing it could push the state's wealthiest residents out and ultimately hurt revenues. Nine Democratic state lawmakers signed an open letter opposing it, writing that "while well-intentioned, this measure will blow a massive hole in our state budget in the years ahead."

The California Democratic Party endorsed Prop. 40, arguing the revenue is critical to backfill federal funding cuts to health care and food assistance programs.

The window tax precedent

The debate echoes an earlier experiment in wealth taxation. England's window tax, imposed in 1696 and repealed in 1851, charged property owners based on the number of windows in their homes, on the theory that larger homes had more windows and thus more wealth. The tax raised far less than expected because owners boarded up windows and built homes with fewer of them, and landlords passed costs to tenants in higher rents. Charles Dickens called it a tax on "air and light," and economists later cited it as a classic case of "excess burden" — when a tax distorts behavior more than it raises revenue.

The Wall Street Journal's editorial board drew the parallel in an August opinion piece, arguing that a wealth tax would similarly encourage avoidance. The editorial noted that the initiative exempts real estate, which could push billionaires to shift assets into property.

Prop. 3: Making progressive rates permanent

Separately, Proposition 3 would make California's progressive income tax brackets permanent. The brackets, which require the wealthiest residents to pay more, are set to expire in 2031. Joint filers earning up to $22,000 annually pay 1 percent, while those earning over $1.5 million pay 12.3 percent. The Legislative Analyst's Office estimates Prop. 3 would preserve $5 billion to $15 billion in annual state income tax revenue.

California's income tax supplies nearly half of the state's General Fund revenue, funding public education, health and human services, corrections, and higher education. Despite predictions of millionaire flight after the 2016 extension of the progressive brackets, California's share of million-dollar tax filers expanded from roughly 14.9 percent in 2010 to over 16 percent in subsequent years.

Building a Better California endorsed Prop. 3, stating revenues are needed "to protect funding for our schools and healthcare by maintaining the state's progressive income tax rates."

This article is for informational purposes only and does not constitute investment advice.