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    Prediction Market Fees Explained: What Kalshi, Polymarket, Robinhood, and IBKR Actually Charge

    Prediction market fees are where a lot of traders get blindsided.

    By PredictionMarkets.usSaturday, March 7, 20269 min read

    Prediction market fees are where a lot of traders get blindsided.

    Not because the platforms are hiding them in some cinematic villain monologue, but because the fee structures are different enough that you can’t just assume every event contract works the same way. One platform charges per contract. Another charges takers but rebates makers. Another applies fees only on certain market types. And if you’re trading small size or high frequency, those differences stop being trivia and start eating your edge.

    This guide breaks down what the major U.S.-accessible prediction market platforms actually charge in 2026, using official platform docs and current market examples. If you trade on Kalshi, Polymarket, Robinhood event contracts, or Interactive Brokers’ ForecastEx access, you should know this cold before clicking buy.

    For a broader platform comparison, see Kalshi vs. Polymarket comparison. If you’re new to contract mechanics, our guide to how prediction markets work is the right pre-read.

    Why prediction market fees matter more than most beginners think

    Prediction markets look simple: buy a contract between $0.01 and $0.99, get $1 if you’re right, get $0 if you’re wrong. But net returns depend on more than whether your thesis hits.

    Fees change:

    • your true break-even price
    • whether short-term flipping is viable
    • whether passive order placement is worth the patience
    • how much edge you need to overcome transaction costs

    That matters even more in markets where prices already encode crowd information efficiently. The Commodity Futures Trading Commission describes event contracts as derivatives whose payoff depends on a specified event, occurrence, or value, and notes that designated contract markets self-certify many new listings while remaining subject to CFTC oversight and customer-protection requirements. Source: https://www.cftc.gov/IndustryOversight/ContractsProducts/index.htm

    And regulators are not treating these markets as some toy side quest. In February 2026, the CFTC’s Division of Enforcement issued an advisory after two Kalshi-related enforcement matters involving misuse of nonpublic information and fraud in prediction markets, underscoring that the Commission has “full authority to police illegal trading practices” on designated contract markets. Source: https://www.cftc.gov/PressRoom/PressReleases/9185-26

    In other words: prediction markets are real financial products, and the fee schedule is part of the product.

    The short version: how the big platforms price fees in 2026

    Before getting into the weeds, here’s the practical overview.

    That already tells you something important: “what are prediction market fees?” does not have one clean industry-wide answer. The industry is still a mess of different exchange models.

    Kalshi fees: not flat, not identical across every market

    Kalshi’s fee language is more nuanced than the lazy summaries you see on affiliate sites.

    According to Kalshi’s help center, the platform charges a transaction fee on the expected earnings on a contract, publishes the full math in its fee schedule PDF, and notes that some markets have different fees from others. Kalshi also says some markets may include maker fees for resting orders that eventually execute. Sources: https://help.kalshi.com/en/articles/13823805-fees and https://help.kalshi.com/en/articles/13823805-fees

    That means two things:

    1. You should not assume every Kalshi market has the same fee treatment.
    2. You should check the specific contract details before trading size.

    That second point matters because Kalshi often carries some of the biggest U.S. event-contract liquidity. In the latest live non-sports snapshot available during this writeup, Kalshi markets such as Will Iran close Strait of Hormuz before May 2026? were trading with about $675.2K in 24-hour volume, while the next Supreme Leader of Iran market showed roughly $332.3K in 24-hour volume. The point isn’t that these are the markets you should trade. The point is that fees matter most where people actually trade, and Kalshi has enough liquidity in major news contracts that active traders can’t afford to hand-wave costs.

    What Kalshi traders should actually watch

    If you’re comparing Kalshi vs Polymarket fees, that alone makes Kalshi feel more like an exchange product that requires you to read the damn rules before trading.

    Polymarket fees: mostly free on the core platform, but not universally anymore

    Polymarket is where fee discussions get sloppy because people collapse multiple products into one sentence.

    The official Polymarket trading docs say the vast majority of Polymarket markets have no trading fees, including no deposit or withdrawal fees from Polymarket itself and no fees to trade shares on most markets. But the same docs also say some markets now carry taker fees, including all crypto markets starting March 6, 2026, plus NCAAB and Serie A markets deployed after the activation date. Source: https://docs.polymarket.com/trading/fees.md

    That’s a meaningful change. If you still think “Polymarket has no fees” in every case, you’re already outdated.

    The docs also publish the formula for those fee-enabled markets and show that the effective rate varies by share price, peaking at 1.56% at 50% probability for the crypto fee table shown in the documentation. Source: https://docs.polymarket.com/trading/fees.md

    Separately, Polymarket US publishes a simpler exchange schedule: 0.30% taker fee on total contract premium and a 0.20% maker rebate, with a minimum fee or rebate of $0.0010. Source: https://www.polymarketexchange.com/fees-hours.html

    So the cleanest way to explain Polymarket fees in 2026 is this:

    • the main platform is still mostly fee-free
    • some market categories now carry taker fees
    • Polymarket US publishes its own explicit 10-basis-point taker fee schedule

    That’s not contradictory. It’s just not simple.

    Live example: why Polymarket fees matter more as volume scales

    Polymarket remains one of the deepest liquidity venues in the category. In the current top markets pull used for this article, the Fed decision in March event showed about $18.1M in 24-hour volume, while the Democratic Presidential Nominee 2028 event showed about $7.1M in 24-hour volume. On a platform doing that kind of size, even “small” fee changes stop being small if you trade actively.

    Robinhood event contract fees: simple enough that beginners actually understand them

    Robinhood’s event-contract fee model is easier to explain.

    Its support article gives a plain-language example showing that if you buy a contract for $0.60, the commission is $0.01, bringing the total cost to $0.61 per contract. Robinhood’s published fee schedule also lists event contract commissions of $0.01 per contract, per side. Sources: https://robinhood.com/us/en/support/articles/robinhood-event-contracts/ and https://cdn.robinhood.com/assets/robinhood/legal/RHD_Fee_Schedule.pdf

    That simplicity is part of Robinhood’s pitch. The tradeoff is that Robinhood is better understood as a distribution layer for event contracts than as the deepest standalone exchange destination. In the U.S. prediction market stack, Robinhood offers accessibility and familiar onboarding, but it does not erase the need to understand cost per contract.

    Who Robinhood fees hit hardest

    Robinhood’s $0.01-per-side structure is easy to calculate, but it can feel heavier for:

    • smaller contract sizes
    • traders who enter and exit often
    • traders chasing tiny edge on short-dated contracts

    The beginner trap is assuming “simple” means “cheap.” Sometimes it does. Sometimes it just means the fee is obvious.

    Interactive Brokers and ForecastEx fees: cheap on paper, but know which product you’re using

    Interactive Brokers’ event-contract commission page makes an important distinction.

    For ForecastEx contracts, IBKR lists $0.00 per contract under both tiered and fixed commission columns, with no third-party fees shown on that page. For CME event contracts, IBKR lists $0.01 per contract under both tiered and fixed pricing, plus exchange and regulatory fees disclosures. Source: https://www.interactivebrokers.com/en/pricing/commissions-events.php

    That’s an unusually clean split, and it means traders need to know whether they’re looking at ForecastEx exposure or CME event contracts before comparing “IBKR fees” with anything else.

    This is also why blanket “best prediction market app” rankings are usually garbage. They mix:

    • direct exchanges
    • broker interfaces
    • white-labeled distribution partners
    • different regulatory wrappers

    and then pretend a one-line fee summary settles the issue. It doesn’t.

    Which prediction market platform is cheapest?

    Annoying answer: it depends on what you trade.

    But the non-annoying version is still useful:

    So no, there isn’t one universal winner. Anyone telling you otherwise is probably optimizing for affiliate conversions, not accuracy.

    The right way to compare prediction market fees

    If you’re serious, compare platforms across five dimensions instead of just staring at one fee number.

    1. Commission structure

    Is the fee per contract, based on premium, based on expected earnings, or conditional on market type?

    2. Maker vs taker treatment

    A venue with rebates for passive liquidity can be much cheaper for patient traders than it looks at first glance. Source: https://www.polymarketexchange.com/fees-hours.html

    3. Market-specific exceptions

    Kalshi and Polymarket both now have enough nuance that “one fee schedule for the whole platform” is too simplistic. Sources: https://help.kalshi.com/en/articles/13823805-fees and https://docs.polymarket.com/trading/fees.md

    4. Liquidity and spread

    A low explicit fee on a thin market can still be worse than a slightly higher fee on a deep market with tighter spreads.

    5. Regulatory and product structure

    The CFTC’s event-contract framework, self-certification regime, and enforcement posture matter because they shape what gets listed, how surveillance works, and what protections exist. Sources: https://www.cftc.gov/IndustryOversight/ContractsProducts/index.htm and https://www.cftc.gov/PressRoom/PressReleases/9185-26

    FAQ: prediction market fees in 2026

    Do prediction markets charge fees on every trade?

    No. It depends on the platform and sometimes the market category. Polymarket’s docs say most markets are fee-free, but some crypto and NCAAB markets now have taker fees. Robinhood charges $0.01 per contract per side for event contracts. Kalshi uses a different fee framework tied to expected earnings and notes that some markets have special fee treatment. Sources: https://docs.polymarket.com/trading/fees.md, https://robinhood.com/us/en/support/articles/robinhood-event-contracts/, https://help.kalshi.com/en/articles/13823805-fees

    Is Polymarket free to trade?

    Usually, but not always. The official docs say most Polymarket markets have no trading fees, while certain newer crypto, NCAAB, and Serie A markets can have taker fees. Source: https://docs.polymarket.com/trading/fees.md

    How much does Robinhood charge for event contracts?

    Robinhood’s support and fee documents say event contracts carry a commission of $0.01 per contract, per side. Sources: https://robinhood.com/us/en/support/articles/robinhood-event-contracts/ and https://cdn.robinhood.com/assets/robinhood/legal/RHD_Fee_Schedule.pdf

    Does Interactive Brokers charge fees for prediction markets?

    It depends on the contract. IBKR’s commission page lists ForecastEx contracts at $0.00 per contract, while CME event contracts are listed at $0.01 per contract plus related fee disclosures. Source: https://www.interactivebrokers.com/en/pricing/commissions-events.php

    Why do fee differences matter if contracts only settle at $1?

    Because your edge lives in the gap between your entry price, your exit price if you trade out, the final settlement value, and all trading costs in between. On highly efficient markets, a small fee can be the difference between a smart trade and a dumb one.

    Bottom line

    Prediction market fees are not standardized, and pretending they are is how traders make lazy mistakes.

    Kalshi requires more careful reading because fees can vary by market and may include maker fees. Polymarket is still mostly fee-free on the main platform, but not across every market type anymore. Robinhood keeps the math simple with a $0.01-per-contract-per-side structure. Interactive Brokers looks cheapest on paper for ForecastEx contracts, but that depends on the product you’re actually accessing.

    The best habit is brutally simple: before you trade, read the fee page, read the rules, and check the exact market you’re about to touch. Anything else is paying tuition to the market.

    If you want a broader breakdown of how exchanges differ beyond fees, browse Kalshi vs. Polymarket comparison and our explainers on how prediction markets settle.

    Sources

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