Regulation
Kalshi is a CFTC-regulated Designated Contract Market — federally licensed, audited, with mandatory KYC and segregated customer funds. Polymarket is a non-custodial smart-contract protocol on Polygon. It is not licensed in the US and is geo-blocked for US users.
US access
Kalshi works in all 50 states. Polymarket blocks US IPs and requires geofencing acknowledgement; using a VPN to bypass it violates Polymarket's terms.
Settlement currency
Kalshi settles in USD via ACH. Polymarket settles in USDC on Polygon — you need a crypto wallet, USDC, and a bridge to get money in and out.
Liquidity and market breadth
Polymarket has had deeper liquidity historically on a few headline political and crypto markets. Kalshi has broader coverage of regulated US categories — macro data, weather, sports, entertainment — and the gap has narrowed sharply through 2025–2026.
Tax treatment
Kalshi issues 1099-Bs and the IRS treats event-contract gains as Section 1256-style or capital, depending on the contract. Polymarket gains are crypto disposals — every fill is a taxable event in USDC terms.
Who should use which
If you're a US trader who wants regulated, USD-denominated event contracts with a 1099 at year-end, Kalshi is the clear default. Polymarket is for non-US users or US users who already live in DeFi and accept the regulatory ambiguity.