For most of its existence, Polymarket's pitch was simple: no trading fees. Zero. You paid the spread, nothing else. That was a real advantage over Kalshi, which charges a taker fee on every transaction, and it attracted a lot of volume from traders who were tired of being nickel-and-dimed by fee structures on other platforms.
That changes on March 30, 2026.
What's happening
Polymarket is rolling out fees across all major market categories - Politics, Finance, Economics, Tech, Culture, Weather, Mentions, and more. Crypto and Sports already had fees; now essentially everything does.
The headline numbers look small. Peak fees land between $0.44 and $1.07 per 100 contracts depending on the category, with Crypto being the most expensive and Sports the cheapest at peak. But the way these fees are structured is worth understanding before you write them off as noise.
How the fee actually works
Fees aren't a flat percentage of your trade. They're a function of where the contract is priced.
The formula:
fee = contracts × price × feeRate × (price × (1 − price))^exponent
That price × (1 − price) term shapes the curve - it's highest near the middle of the range and falls toward zero at both extremes. A contract priced at 5 cents or 95 cents carries almost no fee. But there's also a leading × price multiplier, which means the curve isn't symmetric: it peaks not at 50¢ but at around 67¢ for most categories, and skews toward higher prices.
The chart below shows this for each category across 100 contracts.
Polymarket new Fee Structure
The exponent changes the curve's shape. An exponent of 1 gives you the standard skewed curve peaking around 67¢. An exponent of 0.5 (used for Economics and Weather) pushes the peak further right to around 75¢ and keeps fees elevated across a broader range of prices. An exponent of 2 (Other/General, Mentions) does the opposite: the curve spikes sharply near the peak price and drops off steeply on both sides.
In practice, this means your costs are highest when you're trading contracts priced in the 60–75¢ range - not at the uncertain 50¢ midpoint as you might expect. Markets where the crowd has already tilted toward a likely outcome are actually the most expensive to trade.
The maker rebate
The fee revenue doesn't just disappear into Polymarket's pocket - at least not all of it. A portion goes back to market makers through the Maker Rebate Program, distributed in USDC daily.
The rebate percentage varies by category:
- Finance: 50% - the most generous, likely to attract liquidity into a category that's historically thinner
- Crypto: 20% - smallest rebate, but highest fee, so makers still get meaningful compensation
- Everything else sits at 25%
This is a deliberate structural choice. By routing taker fees back to makers, Polymarket is trying to deepen liquidity without eating all the margin themselves. Tighter spreads benefit everyone, especially on markets where the bid-ask gap has historically been wide.
Whether it works depends on whether the rebates are large enough to shift behavior. On high-volume categories like Crypto and Politics, probably yes. On thin categories like Weather, the jury's still out.
How this compares to Kalshi
Kalshi's fee formula charges a percentage on both sides of the market, calculated as feeRate × contracts × price × (1 − price) . Same general shape - peaks at 50¢, tapers at the extremes. Their taker fee runs around 7%, which peaks at roughly $1.75 per 100 contracts.
Polymarket's new structure is meaningfully cheaper across all categories. Crypto is their most expensive at $1.07 peak, Politics, Finance, and Tech each land at $0.59, and Sports is just $0.44. Even at its priciest, Polymarket tops out at roughly 60% of Kalshi's peak fee.
For traders who've been choosing Polymarket over Kalshi partly because of zero fees, the math shifts - but Polymarket remains the cheaper platform by a significant margin. The more interesting question is what happens to markets that trade on both platforms simultaneously. Both are now charging fees with similar curve shapes, but at very different rates. The cost structure of cross-platform positions is now more complex to model.
What this actually means
For casual traders, the fees are small enough that they probably won't change behavior much. At the Politics peak price of around 67¢, you're paying $0.59 per 100 contracts. On a $67 position, that's under 1% - noticeable, not catastrophic.
For high-frequency or high-volume traders, the math is different. Every basis point matters when you're running a lot of size, and Polymarket's zero-fee reputation was a genuine edge for that cohort. Some of that volume will adjust.
The maker rebate partially offsets this if you're providing liquidity rather than taking it. If you're consistently posting orders that get filled, you're now getting paid for that, which you weren't before.
The broader context: Polymarket is one of the most-used prediction market platforms in the world by volume, and it's been running fee-free for most of that growth. Introducing fees at scale is a test of whether the liquidity and user base are sticky enough to sustain a business model beyond venture funding. Given the volume numbers from the past two years, there's reasonable evidence they are.
Effective March 30, 2026. Geopolitical and world events markets remain fee-free.
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