Prediction markets had a monster year. Election cycles, Fed decisions, sports, even weather: if it can resolve yes or no, someone is trading it on Polymarket. And because the on-chain platform never sends a tax form, a lot of traders have quietly decided their winnings do not exist as far as the IRS is concerned.
That assumption is wrong in two separate ways, and the second one catches even careful people off guard.
Way one: winnings are taxable with or without a form
No 1099 does not mean no tax. Polymarket’s on-chain platform takes no KYC and files nothing with the IRS, but US taxpayers owe tax on prediction profits regardless. The unsettled question is only how to classify them. Gambling income, capital gains, and Section 1256 contract treatment all have advocates among tax professionals, and each produces a different bill. Most traders report winnings as capital gains, though the IRS has never blessed any single position.
What the IRS does see is the edges of your activity. The exchange where you bought USDC files a 1099-DA. The exchange where you cashed out files one too. When six figures flow out of Coinbase, disappear into a wallet, and come back larger, the mismatch is visible even if the middle is not.
Way two: every trade is also a crypto disposal
This is the layer most traders miss entirely. Polymarket settles in stablecoins: USDC historically, converted to pUSD since April 2026. Under IRS property rules, every purchase of an outcome share, every sale, every redemption, and arguably the USDC-to-pUSD conversion itself is a disposal of a digital asset.
One bet can generate five reportable events. Four of them round to zero gain because stablecoins hold their peg. They still belong on Form 8949, and the burden of proving those zeros falls entirely on you, because nobody sends you records.
Skip the paperwork and the risk is not just an underreporting notice. Blank cost basis on a cash-out can make an exchange’s software, or the IRS, treat your entire withdrawal as profit.
What a clean Polymarket year looks like
Export your full transaction history and wallet activity now, not in April. Match every deposit to the exchange transaction that funded it and every withdrawal to where the money landed. Keep the resolution records for winning positions, because your profit calculation starts there.
Losses work in your favor if you can document them: under the common capital-asset position they offset other gains without limit, then up to $3,000 of ordinary income a year, with the rest carried forward.
For a checkpoint-by-checkpoint breakdown of the whole picture, including what the QCX-run US exchange changes and how the digital asset question on Form 1040 applies, the crypto tax specialists at Count On Sheep maintain a detailed guide to Polymarket taxes
Prediction markets reward people who price reality accurately. The reality here is that the IRS treats your winnings as income and your stablecoin trail as property, and the traders who reconcile both now are the ones who keep what they won.
