Kalshi and Polymarket taxes: what the venues send, and what they don't
Facts about reporting, not tax advice. The IRS has not issued formal guidance on event contracts; talk to a CPA who knows trader taxation.
What forms you get
| Venue | Forms reported by tax practitioners |
|---|---|
| Kalshi | When IRS thresholds are met: 1099-INT (interest), 1099-MISC (credits and rewards), and 1099-B / 1099-DA for crypto transfers. Trading gains are not on any 1099; Kalshi provides a FIFO profit-and-loss statement instead. |
| Polymarket US | Not published. The venue's documentation has no tax-forms page; accounts are identity-verified under CFTC rules. |
| Polymarket (global) | No forms issued, per tax practitioners; the on-chain record is the audit trail. Not available to US accounts. |
What that means
The absence of a form does not remove the obligation to report. Practitioners describe exporting the full trade history, computing net proceeds minus cost, and reporting the result — with an open question about characterization (Section 1256 contracts, gambling income, or ordinary income), on which the profession has not settled. Pick one reasonable treatment, apply it consistently, and document it.