Form 1099-B

Form 1099-B is an information return that brokers and exchanges send to both you and the IRS. It reports the proceeds from the sale or disposition of securities, futures, and other financial instruments.

Which prediction market platforms issue 1099-B?

• Kalshi: Yes — issues 1099-B for all traders with $10+ in proceeds
• Robinhood: Yes — issues consolidated 1099 including 1099-B for event contracts
• Polymarket: No — unregulated, does not issue tax forms
• DraftKings: May issue W-2G for large wins, but not typically 1099-B

What's on the form

A 1099-B reports: date acquired, date sold/settled, proceeds, cost basis (if known), and whether the gain/loss is short-term or long-term. This information maps directly to Form 8949.

Important: The IRS gets a copy

When you receive a 1099-B, the IRS has already received the same information. If the numbers on your tax return don't match, you may receive a CP2000 notice. You must either report the amounts as shown or file with an explanation of any adjustments.

No 1099-B ≠ no tax obligation

Even if a platform doesn't issue a 1099-B (like Polymarket), you're still legally required to report your income. The IRS can discover unreported income through other means, including blockchain analysis for on-chain platforms.