Polymarket vs PredictIt (2026): Global Liquidity vs Political Depth

The Fee Comparison: Not Remotely Close

Polymarket US charges a variable taker fee — up to ~1.74¢ per $1 contract at a 50¢ midpoint (Θ=0.0695 model) — with maker rebates and free withdrawals. PredictIt takes 10% of the profit on every winning trade and nothing on a losing one; standard withdrawals are free.

On a winning trade PredictIt's cut is several times larger. On 1,000 contracts bought at 50¢ that win $500:

• Polymarket cost: At most about $17.38 in taker fees on entry (0.0695 × 1,000 × 0.50 × 0.50), charged win or lose
• PredictIt cost: $50 in profit share; nothing if the trade had lost, and the withdrawal is free

For active traders — anyone who places more than a handful of trades per year — this fee differential is the most important fact in the comparison. PredictIt's fees are priced for an era when it had no serious regulated competition. They were never revised following Kalshi's 2021 launch or Polymarket's 2025 CFTC registration.

The only context where PredictIt's fees are acceptable: if you are paying for access to a resource that cannot be replicated elsewhere at a reasonable cost. For researchers, that resource is ten years of US political market data. For active traders, no such justification exists.

Market Breadth: No Contest

Polymarket offers 1,200+ active markets spanning US and international politics, crypto/tech, AI, sports, economics, and global events. PredictIt offers primarily US political events with minimal coverage of other categories.

For a political event trader whose interest extends beyond US borders — international elections, EU policy outcomes, major global geopolitical events — Polymarket is the only regulated option. PredictIt simply does not cover these markets.

Within US political markets specifically, Polymarket has caught up significantly. Major US political events (presidential elections, congressional races, Supreme Court nominations) have competitive liquidity on Polymarket's global platform, often exceeding PredictIt's liquidity on the same events (constrained as it is by the no-action framework's trader limits).

Funding and Custody: Both in US Dollars

PredictIt accepts USD directly via ACH or credit card. Polymarket US takes US dollars by debit card, bank transfer (ACH) or wire; withdrawals are free and go back to the original funding source. Both are custodial: Polymarket US holds your cash in your account at its clearinghouse.

The USDC-on-Polygon setup with a self-custody wallet belongs to Polymarket's international app, where US residents can close existing positions but cannot open new ones. For a US trader, funding no longer separates the two platforms — fees, market breadth, historical data and tax reporting do.

Note: Kalshi also accepts USD and charges much lower fees than PredictIt — and, unlike either platform here, it offers CPI, FOMC and GDP markets.

PredictIt's Irreplaceable Advantage: Historical Data

PredictIt has one genuine advantage that Polymarket cannot replicate: ten years of continuous US political market data from 2014 through 2026.

Polymarket launched in 2020. Its US political market data begins with the 2020 presidential election cycle. Events from 2014 to 2019 — including three congressional elections and one presidential race — exist only on PredictIt. Academic researchers who study prediction market accuracy for US political events often cite PredictIt specifically because its dataset predates all alternatives.

Victoria University of Wellington's ongoing academic partnership with PredictIt has produced peer-reviewed political science research that treats PredictIt markets as the canonical source for US political probability data. This academic credibility is meaningful in research contexts even as PredictIt's competitive position as a trading platform has weakened.

For traders, this historical advantage is marginal. What matters is current pricing accuracy and liquidity — and Polymarket's global user base and AI agent market-making (Polystrat) provide competitive political market pricing without historical data.

Tax Treatment: PredictIt Issues a 1099

PredictIt issues Form 1099 to US traders with $600 or more of net profit in a calendar year (PredictIt FAQ). Polymarket US's participant agreement covers electronic delivery of tax forms including Form 1099-B, but Polymarket has not said whether one is issued for event-contract profits.

There is one practical difference: PredictIt deducts its 10% profit share at resolution, so your account balance already reflects the platform deduction. You report your net gains after the platform fee. Polymarket operates at gross — you receive your full contract proceeds and must calculate net gains after accounting for fees on your own.

Until Polymarket US says whether it issues a 1099 for event-contract profits, keep your own record of every trade.

For comparison, Kalshi does not issue a 1099 for event-contract profits; it provides a monthly profit-and-loss statement (Account → Tax Info) instead.