Can I change the date on a ticket I have already issued through your flight booking API, or does my customer have to cancel and rebook?

Yes, in many cases you can change the date on a ticket you have already issued, but it depends on the airline and on the fare rules attached to that particular ticket, so it is not something that works the same way on every booking.

Where the airline allows it and the supplier behind the fare supports it, the flight booking API lets you pull up the existing booking, ask for the new dates, and get back what the change will cost, both the airline change fee and any difference in the fare itself. You show that to your customer, confirm it, and the ticket is reissued for the new dates. The booking reference often stays the same, which means there is less for you to explain to the traveller.

There are plenty of cases where it will not work that smoothly. Some of the cheapest fares do not permit changes at all, and the only route is to cancel if the rules allow and book again. Low cost airlines frequently handle changes only on their own systems, so the API may show you the booking but decline the change. Some suppliers also insist that changes go through their own support desk rather than automatically, particularly very close to departure or once the trip has already begun. In those situations you can still see the booking in your system, but the change is done by raising a request rather than in one step.

Before you rely on this, check with each supplier you are connected to whether date changes are handled automatically or need a manual request, and make sure your staff can tell which fares are changeable at the point of selling them.