Proposition 40 would impose a one-time tax of up to 5% on individuals and trusts with more than $1 billion in covered assets. Covered assets include businesses, securities, art, collectibles, and intellectual property, while real property and certain pension and retirement assets are excluded. The measure directs 90% of revenue to healthcare and 10% to food assistance or education-related programs. California’s fiscal analysis expects a temporary revenue increase but also warns that behavioral responses could reduce other state tax receipts over time. A one-time tax sounds narrower than a permanent wealth tax, but billion-dollar portfolios are mobile and difficult to value. The right question is not only how much revenue can be collected once, but what rule is administrable and what behavior it changes afterward.