Google co-founder Sergey Brin spending more than $100 million fighting California wealth tax

The fight over a proposal to tax the assets of California billionaires to fund healthcare is getting more expensive.

Google co-founder Sergey Brin has poured $102 million this year into Building a Better California, a group that’s funding two ballot measures that could block a billionaire tax, data from the California Secretary of State show.

Brin’s latest donation totaled $20 million. It highlights how California’s ultra-wealthy are battling a proposal to tax their net worth.

Brin’s net worth was $284 billion at the start of the week, making him the world’s fourth-richest person, according to the Bloomberg Billionaires Index.

Building a Better California’s website says it’s a nonpartisan group focused on “supporting forward-looking ideas to improve affordability and quality of life for all Californians” while protecting innovation and economic growth. It’s also backing affordable housing efforts.

The group declined to comment about Brin’s contributions.

Building a Better California is bankrolling two ballot measures — Propositions 41 and 42 — that supporters of the billionaire tax say are meant to “trick voters” into nullifying a wealth tax.

Voters will weigh in on the tax proposal, known as Proposition 40, and the other measures in November. The Service Employees International Union United Healthcare Workers West, politicians such as U.S. Sen. Bernie Sanders (I-Vermont), the California Democratic Party and other groups back the wealth tax.

“California billionaire Sergey Brin would rather spend $100 million to fund a shady opposition campaign than simply pay his fair share in taxes so millions of Californians don’t lose their healthcare. That’s shameful. Billionaires already pay much lower tax rates than what working families pay out of every paycheck,” SEIU-UHW Vice President Debru Carthan said in a statement.

Proposition 41 would require audits for new state special taxes. It would bar new state taxes that exempt their revenue from a state spending limit. Proposition 42 would prohibit new taxes on “retirement holdings, individually-owned assets, and other forms of personal savings.” It would bar retroactive taxes on past earnings.

While supporters of the measures say they aim to cut wasteful government spending, improve transparency and protect retirement savings, both conflict with the proposed billionaire tax. That means that they could block the billionaire tax from becoming law, according to the Legislative Analyst’s Office.

If Proposition 41 or 42 receives more approval votes than the proposed billionaire tax proposal, that would nullify the wealth tax.

Proposition 40 imposes a one-time 5% tax on billionaires’ assets. The tax applies to people with a net worth of at least $1 billion who resided in California on Jan. 1. Ninety percent of the tax would fund healthcare, and 10% would go toward education and food assistance.

Supporters estimate that the tax would raise roughly $100 billion to offset federal funding cuts. The Legislative Analyst’s Office said the exact amount is tough to predict, but the state probably would collect tens of billions of dollars.

The proposal also faces a growing amount of high-profile opposition, including from the California Chamber of Commerce, California Gov. Gavin Newsom, the California Teachers Assn. and Planned Parenthood Affiliates of California. Opponents fear that billionaires will flee California and harm the economy.

Meanwhile, billionaires have reduced their ties to California or threatened to move. Brin relocated to Nevada and is buying new property elsewhere, like Florida.

Brin told the New York Times in April that he fled socialism with his family in the 1970s and doesn’t want “California to end up in the same place.”

Ripple Labs co-founder Chris Larsen, venture capitalist Ron Conway and others also have been funding opposition to the billionaire tax.

Building a Better California’s biggest contributors include John Doerr, chairman of venture capital firm Kleiner Perkins; Michael Moritz, former partner at Sequoia Capital; and Patrick Collison, chief executive of fintech company Stripe. Executives from DoorDash, the Wonderful Company, Affirm and Ripple, as well as former Google Chief Executive Eric Schmidt, also contributed to the group, data from the California Secretary of State show.