Polymarket tax forms: what Polymarket US has published

The polymarket.com help center belongs to a separate product and is not in the table. Polymarket’s own documentation describes polymarket.com this way: Polymarket’s international, crypto-based product on a blockchain, separate from Polymarket US.

What that leaves unpublished, as of October 22, 2026: a reporting threshold, a delivery date, any form other than the 1099-B, and any statement of how Polymarket US event contracts are taxed. Where the year is reported without a form is below; how the same trades come out under each common route is on Polymarket taxes.

The year is rebuilt from the activity API, the balance ledger and the CSV reports. Three things about them matter for a form. Fees are not on the activity API’s trades, so a rebuild that reads trades alone leaves them out. The ledger and CSV reports reach back only to May 1, 2026, so neither covers the start of the year. And 3 activity types are payments from the exchange rather than trades (TAKER_FEE_REBATE, REFERRAL_BONUS, LIQUIDITY_PROGRAM), which no Polymarket US document ties to a form.

Every source, its start date and its fields are on Polymarket trade history. The order to pull them in is on how to file Polymarket taxes.

There is no IRS guidance on how event contracts are taxed. Of the people we’ve seen file a Polymarket US year, three routes are the most common, and each has a line for unreported trades.

• For people filing under Section 1256, Form 6781 part I asks filers to list separately each transaction with no Form 1099-B behind it. A Polymarket US position open on December 31 goes there at its year-end price, which Polymarket US publishes only as a book-derived display price, not a trade. Form 6781 for event contracts walks through the lines.
• For people filing as standard capital, Form 8949 box C (short-term) and box F (long-term) are for sales not reported on a Form 1099-B. Prediction market capital gains covers the rows.
• For people reporting the year as gambling, winnings go on Schedule 1 and losses on Schedule A, for those who itemize.

Income counts whether or not a form reports it: the tax code reaches “all income from whatever source derived” (26 U.S.C. §61).

The IRS instructions for Form 1099-B have brokers report profit or loss on regulated futures and Section 1256 contracts in boxes 8 to 11, separately from the proceeds and basis of other sales in boxes 1a to 1e. Which boxes a Polymarket US form used would show how Polymarket US itself reported the contracts, something none of its documents says today.

• A figure in box 11 goes on Form 6781 line 1 for people filing under Section 1256.
• Sales in boxes 1a to 1e go on Form 8949 box A, B, D or E, depending on the holding period and whether basis was reported to the IRS.
• Either way the trade history is the check on the form. A Polymarket US trade has no fee field and its documentation does not say how a form would treat fees, so a difference between the two can be a fee question before it is anything else.