What Betfair Exchange actually charges
Betfair does not price like the US event-contract exchanges, and the difference is not the percentage. It is when you pay at all. Betfair charges commission on your net winnings in a market, so a market you lose costs you nothing in commission. On Kalshi, Polymarket, Robinhood and Novig a losing trade still carries its fee. That single structural fact matters more than any rate comparison, and no table of percentages can express it.
Two architectures, not one rate card
Every venue in this category uses one of two fee models:
| Architecture | Venues | You pay | On a market you lose |
|---|---|---|---|
| Per-contract, on the curve | Kalshi, Polymarket, Robinhood, Novig | on every matched trade | yes, you still pay |
| Share of net winnings | Betfair, Smarkets | only when the market nets you a profit | nothing |
The split follows the regulator rather than the product. The CFTC-regulated US derivatives venues charge per contract; the UK-licensed betting exchanges charge on winnings. Betfair states it plainly:
"Betfair charges a Commission on your net winnings on a market. If you have a net loss on a market you do not pay commission."
If you want the other side of that comparison, see Kalshi fees and Robinhood fees, where the fee is charged whether you win or not.
Which rate applies to you turns on one setting
This is where most published guides go wrong, and where our own earlier reading was wrong twice in opposite directions.
Betfair's charges terms say your commission rate is "determined by your package choice in the 'My Betfair Rewards' section of My Account", and give a worked example on the Basic package:
"You have a net profit in a market of £100. You are opted into the Basic package of My Betfair Rewards. The commission rate in this package is 2%. Therefore the commission is £2.00 (£100 x 2%)."
The Market Base Rate formula that dominates the search results,
Commission = Net Winnings × Market Base Rate × (100% − Discount Rate)
, is real, and which of the two applies to you comes down to one thing. Betfair's support centre states it directly:
"Betfair Exchange charges Commission on winning bets. If you are opted into 'My Betfair Rewards', we use your chosen package to decide on commission rate. Otherwise, we use a [Market Base Rate] according to where you live to calculate your commission."
So there are three routes into the Market Base Rate: you are not opted into My Betfair Rewards, the event is an Australasian Event, or your account is part of a Master/Sub-Account structure. Opted in and betting on anything else, your rate is your package rate.
And the Market Base Rate is set by where you live, the support centre says so even though the charges terms never use the phrase.
Betfair's own worked example of the Market Base Rate path:
"You have net winnings in a market of £400. The Market Base Rate is 5%. Your current Discount Rate is 40%. Therefore the commission you pay is £12 (£400 x 5% x (1-40%))."
Deliberately not asserted: the per-country Market Base Rate figures. Betfair does not publish them as text, the country-by-country table on its help pages is an image, and its terms tell customers to read their own rate from "emails and web messages from Betfair". We have not transcribed the image, and we are not going to repeat numbers from third-party sites, which this project has already found to be wrong about fees three times. If you need your Market Base Rate, it is in your account correspondence.
Betfair says its own site displays the wrong rate
Buried in clause 4.8 of the charges terms is an admission worth reading twice:
"Please note that the Rules tab which is found on each market on the Classic or Old version of Betfair is incorrectly displaying the Market Base Rate as 5%. Please ignore the information about the Market Base Rate on the Classic or Old version of Betfair."
A rate displayed on the market screen, in the product, is wrong, and the correction lives in a terms page almost nobody opens. If you have ever taken 5% as your Betfair commission because that is what the Rules tab said, that is where the number came from, and Betfair says not to use it.
The Discount Rate decays every week
Where a Discount Rate applies, it is not a status you keep. It is a balance that erodes:
- You earn 1 Betfair Point for every 10 pence of commission paid on net winnings, or of implied commission on a net loss. Points accrue whether you win or lose.
- Your Discount Rate is recalculated from your points every Sunday at midnight GMT.
- After each calculation, your points balance is cut by 15%, the weekly decay.
- The discount is capped at 20% until you complete Betfair's KYC checks.
- Discount Rates apply at market settlement, not at bet placement, so a long-dated market may settle at a different rate from the one in force when you traded it.
You can pause the decay with a Betfair Holiday: one on registration, one more every three months, and no more than four unused at a time. A discount that requires you to keep betting to hold onto it is a rebate on activity, not a lower price.
Three charges above the commission
Most customers pay commission and nothing else. The terms describe three further charges that a heavy or profitable account can meet.
Transaction Charges, for high bet counts
Applies only above 5,000 qualifying transactions in any clock hour. A transaction is any placed bet, matched, unmatched, cancelled or lapsed, plus failed API transactions. Successful cancellations are free; failed ones are not.
| Transaction type | Cost per transaction |
|---|---|
| Market-making bet* | Free |
| Any other placed bet | £0.001 |
| Failed transaction, duplicate | £0.005 |
| Failed transaction, any other error code | £0.001 |
* a Put-Up Bet with a backer's stake of £10 or more, or a layer's liability of
£100 or more.
The exemption is the design: bets that add real liquidity are free, and the charge falls on high-frequency order churn.
Expert Fees, for consistently profitable accounts
Betfair states this applies to fewer than 0.5% of customers. An account is only considered once it has bet in more than 100 markets and its last 52 active weeks' gross profit exceeds £25,000.
| Last 52 active week gross P&L | Fee rate |
|---|---|
| Under £25,000 | 0% |
| £25,000, £100,000 | 20% |
| Over £100,000 | 40% |
The fee is charged weekly on gross profit above a Buffer, net of the commission you already generated:
Expert Fee Due = (Weekly Gross P&L − Buffer) × Fee Rate − Weekly Commission Generated
and "Commission Generated" is not simply what you paid. Betfair defines it as half of your commission plus half of an Implied Commission of 2.5% of your market losses, its share of what the people who beat you paid. So the charge targets accounts that win a lot while generating little commission either way.
Turnover Charges, Australian racing
A small number of customers on defined turnover-charge markets pay a percentage of the aggregate value of their matched back bets, triggered when the commission they generate falls below a threshold share of that turnover. The rates differ by market set, 3.0% on the general definition, 2.5% on the NRL set, and qualifying markets are flagged in each market's Rules tab. Betfair says it contacts affected customers before charging.
What this means beside the US exchanges
A per-contract venue charges you on the way in. Betfair charges you on the way out, and only if you are up. For a trader who loses a market, Betfair's commission is genuinely zero where Kalshi's or Polymarket's is not.
For a trader who wins consistently and in size, the direction reverses: the US exchanges keep charging the same small per-contract fee, while Betfair's ladder of Expert Fees is explicitly designed to take a share of sustained profit. The cheapest venue therefore depends on whether you win, which is not a question any comparison table asks.
