This is part of the agreement at the start of ticket sales and is billed at the conclusion of the event.
The only other cost is the charge levied by the payment provider at the point of sale.
Use this configurator to determine the ticket price that best suits your needs. Select your preferred payment gateway and enter a ticket price. For any number of tickets in a transaction, the configurator will tell you the revenue per ticket you will receive after payment gateway and Ticket-Office fees.
If you have a required revenue per ticket, enter that and the price per ticket to charge will be shown.
These figures are based on Paypal charges of 2.99% + 30p per transaction, Square charges of 1.4% + 25p per transaction and Ticket-Office.co.uk charges of 3% of gross tickets sales before payment gateway charges.