Sergey Brin Spends $102 Million Fighting California Wealth Tax That Bernie Sanders Says Would Cost Him $14 Billion

Google co-founder Sergey Brin has spent $102 million (£75 million) to defeat a California measure taxing his fortune once at 5%, a sum Senator Bernie Sanders says he could easily absorb while millions of residents' healthcare rides on the result.

Where the Billions Would Go

Proposition 40, on California's November ballot, would impose a one-time 5% tax on residents worth more than $1 billion (£738 million). About 90% of the revenue would fund the state's public healthcare programmes, including Medi-Cal, with the rest split between education, food assistance, and administration.

Supporters estimate it could raise close to $100 billion (£73.8 billion) at a time when federal cuts threaten California's health system. The measure was pushed by the Service Employees International Union United Healthcare Workers West (SEIU-UHW), which says those cuts could strip a similar sum from state healthcare over five years.

For the roughly 200 billionaires who called California home on 1 January 2026, the bill would come due in 2027, payable over five years. For millions of low-income residents who rely on Medi-Cal, the vote decides whether that funding gap gets filled.

Sanders Puts a Number on Brin's Bill

Brin has become the measure's loudest financial opponent, giving $102 million (£75 million) this year to Building a Better California, according to state campaign filings. The group is backing two rival measures, Propositions 41 and 42, that would cancel the wealth tax if either draws more votes, and it has since put $5 million (£3.7 million) directly into the 'No' campaign.

On 11 August, Sanders took aim at that spending. He said Brin had made $140 billion (£103 billion) since President Donald Trump's election and would owe $14 billion (£10 billion) under the tax while still holding a fortune worth $270 billion (£199 billion). 'So what is he doing?' Sanders wrote. 'Spending $100 million to defeat the proposal.'

Brin has likened the measure to Soviet-era socialism, telling the New York Times he fled the Soviet Union in 1979 and does not want California to follow the same path.

Can the Tax Collect if the Rich Leave?

Brin now lists Nevada as his residence, and state business records show an entity tied to him terminated or moved 15 California limited liability companies (LLCs) late last year, several re-registered in Nevada. That has fed a wider argument that a wealth tax simply chases fortunes to Nevada, Texas, and Florida rather than raising money.

The design of Proposition 40 complicates that claim. Because the tax applies to anyone who was a California resident on 1 January 2026, tax attorneys say leaving afterwards would not avoid it, though the retroactive date is expected to face legal challenge. Six of the state's billionaires reportedly left before or around the cut-off, though they are expected to face residency audits.

A National Bureau of Economic Research working paper found that even if every California billionaire left, it would take about 25 years of lost income tax to equal the roughly $100 billion the one-time levy would raise.

Billionaires on Both Sides

Brin is not alone. Peter Thiel, Ripple co-founder Chris Larsen, and venture capitalist Ron Conway have also spent against the measure, and Governor Gavin Newsom opposes it, telling Politico it 'makes no sense'. Backers include the California Nurses Association, the state Democratic Party, and Representative Ro Khanna. Voters decide on 3 November.