Most airlines allow these unused tickets as full or partial payment toward a new ticket on the same airline. Some fare bases do not permit this, but right now they are the exception. If you cancel before the original departure date, we will contact the carrier to cancel your trip, verify that the ticket is nonrefundable and review the re-use policies. If the old ticket has less value than the new, you must pay the difference at that time. If the old ticket was of greater value than the new, we consult the airline's particular rule.
Some airlines save the excess value in voucher form for future use.
Even so, there is a transaction fee that's not deducted from the excess value. Other airlines require issuance of a new ticket at a ticketing office. For yet other carriers, the excess value is lost. If a reissued ticket MTS handles results in a voucher, the voucher becomes nontransferable and nonrefundable. The most restrictive is Continental, which requires that all travel be completed by one year from the original issue date.