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

The Fee Comparison: Not Remotely Close

Polymarket US charges a variable taker fee — at most ~1.5¢ per $1 contract at a 50¢ midpoint (Θ=0.06 model) — with maker rebates and no fees to deposit or withdraw USDC. PredictIt charges 10% of net profits per market plus 5% on every withdrawal.

This is roughly a 100:1 fee ratio for active traders on profitable positions. On a $500 winning trade:

• Polymarket cost: Approximately $0.50 in taker fees on the initial position entry
• PredictIt cost: $50 in profit share, plus 5% of whatever you then withdraw

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).

Currency: The Non-Negotiable Difference

PredictIt accepts USD directly via ACH or credit card. Polymarket requires USDC stablecoin on the Polygon blockchain.

This is not a minor operational difference. For investors with no existing crypto infrastructure, accessing Polymarket requires: opening a cryptocurrency exchange account, completing additional KYC, purchasing USDC, and either bridging to Polygon or using an on-ramp service. This process typically takes 30–60 minutes and involves managing a non-custodial wallet.

For crypto-native traders who already hold USDC in a Polygon-compatible wallet, this friction is zero. The currency difference is binary: if you are already crypto-native, Polymarket's fees and breadth make it the obvious choice. If you are not, PredictIt's USD acceptance removes that friction — at the cost of dramatically higher trading fees.

Note: Kalshi accepts USD directly and charges much lower fees than PredictIt. For USD-only traders who want low fees, Kalshi is the correct answer — not PredictIt.

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: Both Require Self-Reporting

Neither Polymarket nor PredictIt issues IRS Form 1099. Both require US traders to self-report gains and losses.

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.

For either platform, crypto tax software (Koinly, CoinTracker, TaxBit) can automate most of the gain/loss calculation by importing transaction history. This is especially useful for Polymarket, where all transactions are on-chain and therefore importable via wallet address.

By contrast, Kalshi provides automated Form 1099 with no self-reporting required. If tax compliance is a deciding factor, Kalshi is the correct choice over both Polymarket and PredictIt.