California billionaire wealth tax passes at just 25% on both Kalshi and Polymarket

California’s billionaire wealth-tax ballot contract is priced at a 25% chance of passage on both Kalshi and Polymarket, according to defirate.com. The matching readings put the implied probability at roughly one in four.

Matching prices, a weekly decline

The Kalshi probability fell 8 percentage points over the past week to 25%, according to defirate.com. The supplied figures do not include a corresponding weekly change for Polymarket, so they establish agreement on the current probability—not necessarily on how the two markets reached it.

Defirate.com’s average of the two platforms is also 25%. With both venues at the same level, that average adds no difference to the individual readings.

Price and payout

Polymarket’s displayed buy price is 25¢, according to defirate.com. The outlet also reports that $100 placed on Kalshi at the ask would pay $400 if correct, before fees. That figure is the stated payout, rather than net profit.

The supplied material does not provide the contract’s resolution terms, a ballot timetable or an explanation for the weekly decline. Those limits leave the price movement clearer than its cause.

What it means for prediction markets

• Passage remains the less likely outcome in market pricing: both platforms assign it a 25% implied probability.
• Kalshi has moved lower: its 8-percentage-point weekly decline signals a reduced market-implied chance of passage, but the material does not identify a catalyst.
• Cross-platform agreement has limits: identical headline probabilities do not establish identical contract terms, fees or trading conditions.