Kalshi vs Polymarket
Kalshi and Polymarket are the two best-known prediction markets, and they share the same core idea: trade Yes/No contracts on real-world events. But they differ in ways that matter for cost, taxes, and how you fund and trade.
Here is the comparison.
Regulation and money
Kalshi is a CFTC-regulated US exchange that operates in US dollars. Polymarket runs on crypto rails, settling in stablecoin on a blockchain. That single difference cascades into funding, recordkeeping, and tax treatment.
Fees
Kalshi charges small per-trade fees that scale with the contract price, and limit (maker) orders can avoid them. Polymarket has historically charged nothing upfront but taken a cut of net profits. Which is cheaper depends on your win rate and how you trade, since a profit-based fee and a per-trade fee bite differently.
Markets and access
Both list a wide range of events. Kalshi's regulated status shapes which markets it can offer in the US, while Polymarket's crypto-native model gives it a different footprint. Availability and the exact catalog shift over time, so check each for the specific markets you want.
Taxes and recordkeeping
Kalshi's dollar-based, regulated structure is the strongest basis for the contested Section 1256 tax argument, though that remains unsettled. Polymarket's crypto settlement is generally analyzed more like property, and its on-chain activity makes reconstructing your cost basis harder. Neither hands you a complete tax form, so you self-report either way.