If I cancel a flight ticket for my customer, how do I know how much money they will actually get back?

Yes, in most cases you can see what the refund comes to before you confirm the cancellation, but how exact that amount is depends on the airline and on the fare your customer bought.

When you ask to cancel a ticket, the booking engine checks the fare rules attached to that booking and works out the airline cancellation charge, the part of the taxes that comes back, any service charge the airline applies, and your own markup if you added one. That gives you a refund breakdown on screen, so you can tell your customer what to expect before anything is cancelled. For many full service airlines this comes back straight away and is reliable, because the airline lets the refund be calculated and processed automatically through the API.

For some airlines, and for most low cost carriers, it does not work that way. The fare may be almost entirely non refundable apart from a few taxes, or the airline may only accept a refund request that one of their staff has to look at. In those cases you will see the request go through as pending, and the final amount is confirmed only once the airline replies. How long that takes is the airline's decision, not ours. Group tickets, special or promotional fares, and tickets where part of the journey has already been flown are usually handled by request as well, rather than instantly.

Before you cancel anything, open the fare rules on the booking and read the cancellation section, and if refunds are a regular part of your business, ask us which of the airlines you sell support instant refund quotes so you know where to expect a wait.