Polymarket vs Kalshi is the passport, read in either order.

People type Polymarket vs Kalshi and Kalshi vs Polymarket as if the word order picked a winner. It does not. The split is where you live and what you can send.

Kalshi is a CFTC designated contract market. US residents can open it. The book is dollars. Signup is KYC. Idle cash has been advertised around 3.5–4% APY; the live figure is in the app, not in this sentence. The taker fee peaks near 50¢ and caps at $1.75 per 100 contracts.

Polymarket is the USDC venue. It does not run the same KYC door, and it does not take a US member the way Kalshi does. A percent of notional is a different shape from Kalshi’s formula. Run a real clip on both before you call one cheaper.

If the passport is American, Kalshi is the regulated default. If you already hold USDC and Kalshi’s list says your address is closed, that is a different problem — not a reason to pretend you live somewhere else. The full table is the comparison guide. StartKalshi does not place the order on either venue.