California’s proposed billionaire tax appears to face an uphill battle, with prediction-market traders assigning the measure a relatively low chance of approval as voters prepare to weigh 14 statewide propositions next week.
Displayed markets on Kalshi and Polymarket International show several initiatives with strong odds of passing. Others—including proposals requiring voter identification and directing community health clinics to spend more on patient services—are attracting considerably less support.
Here is how the current market-implied probabilities compare:
Housing and infrastructure
- Proposition 1 — Housing bonds: Authorizes $11.25 billion for affordable housing and housing programs for veterans. Kalshi: 75% | Polymarket: 89%
- Proposition 37 — Homebuyer loans: Establishes a state-backed low-interest loan and mortgage program for middle-income buyers purchasing eligible newly built homes. Kalshi: 91% | Polymarket: 82%
State finances and elections
- Proposition 2 — Rainy Day Fund: Increases deposit limits and raises the maximum balance allowed in the state’s reserve fund. Kalshi: 92% | Polymarket: 72%
- Proposition 4 — Public campaign financing: Eliminates the ban on using public funds to finance election campaigns. Kalshi: 9% | Polymarket: 22%
- Proposition 5 — Recall elections: Revises the recall process for statewide officials by ending the requirement that voters choose a replacement at the same time as they vote on removal. Kalshi: 9% | Polymarket: 26%
Taxes and spending rules
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- Proposition 3 — High-earner tax: Makes a temporary income-tax increase permanent, with the revenue supporting public schools and health care. Kalshi: 95% | Polymarket: 94%
- Proposition 40 — Billionaire tax: Creates a one-time wealth tax on billionaires to help pay for health care and educational facilities. Kalshi: 25% | Polymarket: 23%
- Proposition 41 — Tax spending limits and audits: Limits new state taxes that do not comply with specified spending rules and requires independent audits of revenue raised through special taxes. Kalshi: 54% | Polymarket: 59%
- Proposition 42 — Property and retroactive taxes: Bars the state from imposing new personal property taxes or enacting tax laws retroactively. Kalshi: 79% | Polymarket: 80%
- Proposition 43 — Local tax votes: Increases the approval threshold for certain local tax increases. Kalshi: 19% | Polymarket: 25%
Voting, health care and the environment
- Proposition 39 — Voter ID: Requires voters to present government-issued photo identification at the polls. Kalshi: 14% | Polymarket: 21%
- Proposition 38 — Immunology research bonds: Authorizes $8.4 billion in state bonds for medical research facilities. Kalshi: 82% | Polymarket: 72%
- Proposition 44 — Clinic spending: Requires community health clinics to allocate at least 90% of their revenue to patient programs and services. Kalshi: 8% | Polymarket: 11%
- Proposition 45 — Environmental review: Revises the California Environmental Quality Act review process for designated housing, transit and infrastructure projects. Kalshi: 32% | Polymarket: 37%
California voters can trade contracts tied to these political outcomes because prediction markets operate under a legal and regulatory structure distinct from sports wagering.
Under federal law, prediction-market contracts are classified as financial derivatives rather than sports bets. That designation allows Kalshi and the US-regulated version of Polymarket to operate within the financial-markets framework.
These percentages reflect the market’s implied probability that each measure will pass—not an official projection or election result.
The odds may change as traders buy and sell contracts, and they offer no guarantee of how Californians will ultimately vote.
