California is home to roughly 200 billionaires who collectively control about $2 trillion in wealth, much of which remains largely untaxed under current income tax systems. The vast fortunes held by these individuals typically avoid traditional income taxation because they are not classified as "income" under existing tax codes.

The structure of billionaire wealth often consists of assets like stocks, real estate, and business holdings that generate value through appreciation rather than regular income payments. This means that while these assets may increase dramatically in value over time, they do not trigger income tax obligations until they are sold.

In response to this tax gap, lawmakers have proposed wealth tax legislation that would directly target billionaire assets. Senator Bernie Sanders has proposed a 5% annual wealth tax specifically targeting billionaires, which builds upon similar legislative efforts already under consideration in California.

The California wealth tax proposal has garnered support from health care labor unions, which view such measures as a potential revenue source for public programs. These proposals represent a shift from traditional income-based taxation toward asset-based tax systems.

Wealth taxes face significant implementation challenges, including asset valuation difficulties and questions about constitutionality. Several European countries have attempted similar wealth taxes with mixed results, often encountering administrative complexities and capital flight concerns.