What is Commission?
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. Your Discount Rate reduces the amount of commission you pay and is based on how many Betfair Points you’ve earned. We reward you with Betfair Points when you win or lose on the Betfair Exchange.
 
When do I pay Commission?
Betfair charges Commission only on your net winnings on a market. You do not pay commission on losing bets.

How much Commision do I pay?
This is how it is calculated: Commission = Net Winnings x Market Base Rate x (100%-Discount Rate).