Premium Charge Summary
You will only be considered for the Premium Charge if, over the lifetime of your account, you satisfy the following criteria:
Your account is in profit;
Your total charges generated are less than 20%† of gross profits; and
You bet in more than 250 markets.
Two further conditions reduce the likelihood that you will be required to pay the Premium Charge:
Any single win that constitutes more than 50% of your gross profits over the lifetime of your account will be excluded from the calculation; and
Each customer will have a lifetime allowance of £1,000 against the Premium Charge.
Each week the customers who meet all the conditions set out above will be charged the lesser of:
The difference between 20%† of the previous week’s gross profits and the total charges generated during the week; and
The difference between 20%† of gross profits and the total charges generated during the lifetime of the account.
http://www.betfair.com/AUS_NZL/aboutUs/Betfair.Charges/