Some airlines charge passengers a re-booking fee in order to claim a voucher or credit.  In order to be eligible for a credit or voucher from these airlines, the price of your flight must drop to the point where it exceeds any re-booking fee.  Yapta will automatically take any of these re-booking fees into account so you are only notified of the price drop once your flight becomes eligible for a voucher or credit.

Click here for a complete list of those re-booking fees Airline change fees .

How to obtain a voucher or credit from the airlines