A one-time tax on California billionaires would levy a single surcharge on ultra-high net worth residents' wealth as approved by voters.

Passage decides whether the state raises a large, earmarked windfall for programs like homelessness and education and whether similar taxes spread to other states or face prompt legal fights.

California voters and the state's richest residents will decide the measure at the ballot.

Governor Newsom, the legislature, tax-reform advocates, anti-tax donors, county election officials, and state courts will shape implementation, defense, and enforcement after the vote.

Polling on ballot support, likely-voter modeling, and turnout among young and suburban voters will shift projected passage odds.

Campaign cash from wealthy donors, high-profile endorsements, legal pre-emptive challenges, and ballot-language litigation are immediate levers that can reverse or cement momentum.

Election night counts, absentee ballot tallies, and county-level turnout breakdowns will show where the measure is winning or lagging.

Watch pre-election fundraising reports, any court rulings on ballot wording, endorsements from labor or tech leaders, and post-election legal challenges that could delay or void implementation.