United Airlines has a 24-hour flight change policy that is comparable to its 24-hour flight cancellation policy. Passengers who have booked tickets seven days or more prior to departure have up to 24 hours from the time of first booking to make changes to their reservation free of charge. Except for Basic Economy tickets, this regulation applies to all tickets. United Airlines flight change policy prohibits changes to Basic Economy tickets, even if made within 24 hours. The best option is to cancel (for free) within 24 hours and buy a new ticket. When making adjustments to refundable tickets, United Airlines will not charge a change fee. However, you will be responsible for the price difference if you upgrade to a more expensive ticket. Depending on the circumstances of the ticket, the cost difference may be refunded to the original payment method if you switch to a cheaper alternative.