Kalshi launched as America's first federally regulated prediction market. The CFTC approval process took years, multiple legal battles, and ultimately reshaped how regulators think about event contracts in the United States. That regulatory legitimacy is real - and so is the cost structure that comes with operating a licensed derivatives exchange.
Their taker fee is 7%. Here's what that actually means when you place a trade.
Two rates, not one
Kalshi has a two-tier fee structure: 7% for takers, 1.75% for makers.
Takers are orders that match immediately - you cross the spread and take what's already sitting in the book. Makers are orders that rest and wait - you post a limit price and let someone else come to you. The 4:1 ratio between the two rates is Kalshi's mechanism for incentivizing liquidity provision: if you're consistently posting orders that get filled rather than crossing the spread, you pay significantly less.
The concept is similar to Polymarket's maker rebate program, which launched in January 2026 for 15-minute crypto markets and expanded with the broader fee rollout on March 30, 2026. The mechanics differ - Polymarket refunds a portion of taker fees to makers daily in USDC, Kalshi simply charges makers less upfront - but the underlying incentive is identical: reward people who add depth to the order book rather than drain it.
How the fee actually works
The formula:
fee = round_up(feeRate × contracts × price × (1 − price))
The price × (1 − price) term is doing most of the work. It's the mathematical expression for the variance of a binary event: highest when the outcome is most uncertain, falling toward zero as a contract approaches near-certainty in either direction. A contract at 5¢ or 95¢ - essentially already resolved - carries almost no fee. A contract at 50¢ - maximum uncertainty - carries the maximum fee.
This makes Kalshi's curve perfectly symmetric around 50¢. The fee is identical at 30¢ and 70¢, identical at 20¢ and 80¢, identical at 10¢ and 90¢. There's no skew toward higher-priced contracts, no category-specific exponents - just one clean curve that peaks at the midpoint and mirrors itself.
Kalshi vs. Polymarket Fee Visualization
In numbers: 100 contracts at 50¢ costs $1.75 in taker fees. Move to 30¢ or 70¢ and you pay $1.47. Drift toward the extremes - 10¢ or 90¢ - and fees drop to $0.63. Maker fees at the same checkpoints: $0.44 at 50¢, $0.37 at 30¢ or 70¢, $0.16 at 10¢ or 90¢.
The rounding mechanic
Fees are always rounded up to the nearest cent. This matters at the margins.
On a 100-contract trade at 50¢, the raw fee is exactly $1.75 - no rounding occurs. But at other quantities or price points, sub-cent remainders get pushed up. Ten contracts at 50¢ produces a raw fee of $0.175, which rounds up to $0.18 - an effective rate of 7.2%, not 7%. The smaller the trade, the more pronounced this effect; the larger the trade, the more it fades into the noise.
For a trading system modeling costs precisely, this means the formula is a floor, not an exact output. The actual fee is always at or above the raw calculation, never below it.
How this compares to Polymarket
Polymarket's fee structure went live on March 30, 2026, with a meaningfully different formula:
fee = contracts × price × feeRate × (price × (1 − price))^exponent
The extra leading price multiplier makes their curve asymmetric. Polymarket doesn't peak at 50¢ - it peaks at around 67¢ for most categories, skewing toward higher-priced contracts where the crowd has already tilted toward a likely outcome. The exponent shifts this peak further depending on the category and controls how sharply the curve rises and falls.
At their respective peaks, every Polymarket category is cheaper than Kalshi's taker rate. Crypto is Polymarket's priciest at $0.27 peak; Politics, Finance, and Tech land at $0.15; Sports comes in at $0.11.
But comparing peaks at different prices obscures a bigger gap. If you're trading contracts priced near 50¢ - the zone where genuine uncertainty is highest - Kalshi's $1.75 taker fee sits against Polymarket Politics' $0.12 at the same price. That's a 14× difference at an identical contract price, which is the more relevant comparison for most real trading decisions.
The crossing point matters for cross-platform positions. On any matched trade where one leg sits on Kalshi and the other on Polymarket, your combined fee burden depends directly on where in the price range that market is trading. Near-50¢ markets - the ones with the most genuine uncertainty and historically the widest cross-exchange spreads - are where Kalshi's premium over Polymarket is most pronounced.
The deposit fee
Kalshi charges a 2% processing fee on debit card deposits. Debit card withdrawals carry no fee - funds typically arrive back to your card within 30 minutes. ACH transfers and wire transfers carry no withdrawal fee on Kalshi's end, though banks may add their own charges on wires. For traders cycling capital in via debit, the 2% deposit fee is the relevant cost: on a $200 deposit it's $4, on a $2,000 deposit it's $40. Worth including in ROI calculations whenever the trading strategy involves regular capital movement via debit card.
What this means for different traders
For directional traders, 7% on near-50¢ markets is real friction. A 100-contract position at 50¢ runs $1.75 in taker fees entering the position, another $1.75 exiting if you take liquidity again - $3.50 round-trip on a $50 position. That's 7% in fees before any consideration of spread. Short-duration directional trades on uncertain markets are expensive on Kalshi.
For market makers, 1.75% is more workable. In liquid markets where you're consistently earning the spread and the reduced fee applies, the economics are favorable. In thin markets, the risk of sitting in the book longer than intended - and having the market move against you while your order rests - may outweigh the fee advantage.
For cross-platform arbitrage, Kalshi is almost always the dominant fee leg. Polymarket's new fee structure changed the combined cost model, but didn't close the gap - Kalshi remains the expensive side on any matched trade involving both platforms. The minimum viable spread on a Kalshi-involved position needs to clear both legs: up to $1.75 on the Kalshi side at peak, plus the applicable Polymarket category fee on the other. Fee modeling that uses Polymarket's old zero-fee assumption will systematically overstate profitability; the Kalshi leg was always the one doing the heavy lifting on the cost side.
The predictability is worth noting in Kalshi's favor. One formula, one symmetric curve, no category variants, no exponent adjustments. At any given price and contract count, you can calculate the exact fee with no surprises beyond the rounding behavior.
Kalshi's maker rate (1.75%) applies to limit orders that rest in the book and are eventually filled. The taker rate (7%) applies to all orders that match immediately. A 2% processing fee applies to debit card deposits. Debit card withdrawals carry no fee. ACH and wire withdrawals carry no Kalshi fee.
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