Google billionaire throws $100M at battle over California tax

Google co-founder Sergey Brin, the world’s fourth-richest man, has now spent more than $100 million to fight the Billionaire Tax and avoid shelling out an estimated $13.3 billion.

Brin’s net worth is estimated to be around $267 billion. He recently donated another $20 million to Build a Better California, which is an organization that advocated against California’s proposed billionaire tax, according to a recent filing.

Sergey Brin, co-founder of Google, at a dinner at the White House in Washington D.C. on September, 2025. Bloomberg via Getty Images

Google headquarters in New York (pictured). (Christopher Sadowski) Christopher Sadowski

Prop 40, known as California’s billionaire tax, would impose a one-time 5% tax on the net worth of around 200 billionaires that live in the state.

The funding from the proposed tax would be expected to go to California’s healthcare programs.

Governor Gavin Newsom has come out saying he’s against the tax and instead in favor of a “national billionaires’ tax.”

“Today, the office worker can shoulder a higher tax rate than the heiress,” Newsom said on Substack. “We should end the ‘tax-free lifestyle loan,’ the gimmick that lets the ultra-wealthy borrow against their stock portfolios while reporting no taxable income.”

Prop 40 is on California’s ballot in November.

But it’s expected to have competition with other initiatives that could render it moot.

One of the competing measures that made it to the ballot would “require audits of programs funded by new state special taxes”, the California Secretary of State announced in June.

It was the first to qualify of the multiple ballot proposals backed by Building A Better California.

This comes as Trump’s budget cuts are expected to take shape next year. The state’s Medicaid program alone is expected to lose up to $30 billion in federal funding.

Several others are also looking to avoid the tax. Meta founder Mark Zuckerberg reportedly bought a $170 million mansion near Miami this year. Venture capitalist Peter Thiel, former Uber CEO Travis Kalanick and Google co-founder Larry Page have also left the state.

Others like Jensen Huang, Nvidia’s co-founder, have said they’re “perfectly fine” paying the billionaire tax.