There are many reasons to reschedule a flight. Unfortunate events can happen anytime. Nothing is certain in this pandemic situation. Rescheduling a flight can become a necessity sometimes. Some airlines have different policies about rescheduling. Many airlines charge you the penalty fees and the difference between the old ticket and the new ticket and some do not charge you any fees. Due to coronavirus, there are many changes in the airline's policy. In the United States, The fares, on the other hand, will range anywhere from $75 for a domestic flight to over $500 for an international flight.
ALASKA AIRLINES: there are no charges for the domestic flight change. But if you change on the same day then there will be a penalty of $25-$50 for the economy class
AMERICAN AIRLINES: there are no charges for the domestic flight change and international flight change but if you change on the same day then there is a charge of $75-$150 for economy class.
DELTA AIRLINES: In this airline, there are no penalty charges for the domestic flight change and international flight changes. $75 is charged on the same-day change or the economy class.
FRONTIER AIRLINES: this airline has the policy of charging 0-$59 on domestic and international flight change. The same-day flight change is charged $59.
JETBLUE: they have the policy to charge around $75-$200 in domestic and international flight change. The same-day flight change penalty will be $75.
SPIRIT AIRLINES: this airline will charge you the penalty of $90-$100 on domestic and international both. Their same-day flight change can cost around $99.
UNITED AIRLINES: United airlines have the policy of charging up to $400 on international flights. No charges on domestic flight change and on same-day flight change.
SOUTHWEST AIRLINES: Southwest Airlines does not charge any penalty from their customers for the domestic, international, and same day.