Sergey Brin gives $100 million to oppose California billionaire tax

Google co-founder Sergey Brin has now spent $100 million to fight a proposed California tax that would hit billionaires with a one-time 5% levy on their net worth.

Proposition 40, slated for the November ballot, is part of a wave of progressive tax pushes aimed at addressing wealth inequality in a state where the top 1% hold nearly half the wealth. Supporters say it would raise billions for education and homeless services. Opponents argue it targets a small group unfairly and could drive wealthy residents out of state. Brin’s $100 million contribution to the opposition campaign is one of the largest single donations in California political history, dwarfing the $16 million raised so far by supporters.

The tax would apply only to the roughly 100 billionaires living in California. Similar measures have failed in other states, but California’s sheer number of billionaires—including Bloomberg founder Michael Bloomberg and Tesla CEO Elon Musk—makes this fight a proxy for the national debate on taxing extreme wealth. Brin, once a vocal advocate for progressive causes, has largely stayed out of politics in recent years. His involvement now signals how seriously the tech elite view this threat.

If Prop 40 passes, it could set a precedent for other states to follow. But legal challenges are expected over whether a one-time tax on wealth violates constitutional protections. The outcome could reshape how states tax their richest residents—and whether billionaires see California as a place to keep building their fortunes.