Generally there is no written formal policy on change fees. The conditions of carriage (sometimes called terms of transportation or contract of carriage) usually just mentions the existence of change fees without specifying the amount of the fees or any waivers. Often the only mention of change fees on an airline's web site is to specify the amount of the fee.

In my experience, airlines will generally waive change fees when the change was due to a circumstance beyond the traveler's control, such as a death in the family or a serious illness. For example, after my cancer diagnosis the airlines waived change fees and allowed me to use the tickets as a credit toward a future flight.

If the traveler must make a change in the middle of a trip, in most cases the airline will require the traveler to pay a change fee. The traveler can then write a letter to the airline requesting a refund. Sometimes the refund will be granted in the form of flight vouchers good for a year.

It is best to make any changes before the scheduled date of departure.

If an airline ticket is completely unused, contact the airline. Even if the ticket is nonrefundable, you may be able to get a refund of the taxes paid on the unused ticket.