By Biz Carson, Bloomberg

Google co-founder Sergey Brin is continuing to push deeper into California politics by donating to a group that opposes a proposed tax hike on businesses with highly-paid executives in San Francisco.

The $500,000 check is a paltry sum for one of the world’s richest people with a net worth of $304.5 billion, according to the Bloomberg Billionaires Index. But it signals Brin’s desires to shape the state beyond fighting a proposed tax on billionaires and is an early foray into city-level politics.

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The donation, reported in a filing on Wednesday, is to oppose a proposal that would levy a higher tax on companies that have “overpaid” chief executives that’s being put before San Francisco voters in June. The union-backed proposal would impose an eight-fold increase to a gross-receipts tax on any large company doing business in San Francisco where the highest paid executive earns 100 times or more than their median employee.

The measure could generate additional revenue of $250 million to $300 million to the city, according to the city controller’s analysis.

It has met opposition from deep-pocketed billionaires like Ripple Labs’ Chris Larsen who warn it could drive companies out of the city and undo efforts to make it more business-friendly.

Brin so far has spent more than $60 million in state politics this year and has been instrumental in rallying a cohort of like-minded tech billionaires.

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Ultrawealthy donors have spent more than $270 million into state’s politics this election cycle, according to a Bloomberg analysis. Brin recently started a new nonprofit, Compass4, to direct some of his giving. The $500,000 donation against the San Francisco ballot item came through that organization, according to the filing.

A representative for Brin did not respond to a request for comment.

While much of Brin’s money has been directed to measures to counter a proposed billionaires’ tax, the state “has some very systemic issues” that aren’t about one tax or particular person, he told Bloomberg on the sidelines of the Met Gala earlier in May. Living in Nevada with his girlfriend since buying a new lakeside mansion, Brin said they’re now “pretty happy where we are.”

–With assistance from Eliyahu Kamisher.

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