Google billionaire Sergey Brin gets Gavin Newsom's backing to kill California's billionaire tax

American billionaire Sergey Brin has won the backing of California Governor Gavin Newsom for a ballot measure that would wipe out a proposed one-time tax on the state's billionaires and ban similar wealth taxes in the future.

Newsom endorsed Proposition 42 on Oct. 9, less than four weeks before Californians vote on Nov. 3. The measure was funded and placed on the ballot by Brin, the Google co-founder, who could face a tax bill of nearly $14 billion if the billionaire tax passes, according to CNN.

"We all agree that Californians deserve to have their retirement and life savings protected from new state taxes," Newsom said in a statement released by the measure's backers.

How the measures clash

The billionaire tax, Proposition 40, would impose a one-time 5% tax on the assets of people worth more than $1 billion who lived in California on Jan. 1, 2026. About 250 Californians would be affected. Supporters say it would raise about $100 billion, with 90% going to Medi-Cal, the state's health program for low-income residents, to offset federal Medicaid cuts. It is backed by the Service Employees International Union-United Healthcare Workers West.

Proposition 42 would cancel it by banning retroactive taxes. It would also bar new state taxes on personal property, including retirement accounts, investments, business holdings and art collections. A third measure, Proposition 41, also backed by Brin, would subject the billionaire tax's revenue to spending limits and audits. Newsom has not taken a position on it.

Under California law, if two conflicting measures both pass, the one with more votes takes effect. That means Proposition 42 could nullify the billionaire tax even if voters approve it.

Newsom has opposed the billionaire tax for months, with his office saying it has fundamental flaws. Critics argue it would push wealthy residents out of a state that relies on its top 1% of earners for nearly half of its personal income tax revenue.

A $187 million campaign

Billionaires have poured more than $187 million into defeating Proposition 40, compared with about $32 million raised by supporters, according to CalMatters and Quartz.

Brin is the biggest single donor on the opposing side, having given more than $102 million. Other contributors include Ripple co-founder Chris Larsen, venture capitalist John Doerr and Palantir co-founder Peter Thiel. Polls show the electorate closely divided, with a slim majority of likely voters backing the tax in a survey by the Public Policy Institute of California.

Brin, 53, co-founded Google with Larry Page in 1998 while they were graduate students at Stanford University. His fortune rests on his stake in Google's parent company, Alphabet, and Quartz has estimated his net worth at about $270 billion, making him one of the richest people in the world.