United Airlines reimburses passengers for canceled flights when the cancellation is made by the airline. Passengers are entitled to a full refund regardless of the ticket type if they choose not to accept alternative transportation. This policy follows government regulations that require airlines to refund canceled flights promptly. Refunds must be processed within seven business days for credit card payments and within twenty days for other forms of payment. If a flight is significantly delayed, typically over three hours for domestic flights or six hours for international flights, passengers may also be eligible for a refund. Changes such as switching airports, added connections, or downgrades in service class can qualify for refunds as well. Basic Economy tickets generally are non-refundable unless canceled within 24 hours of booking and if booked at least seven days before departure. For other fare types, cancellations may result in refunds minus any applicable fees, depending on the fare rules. Refund requests can be made through United’s website or mobile app and will be credited back to the original payment method. Contacting customer service can help if there are issues with refunds. Overall, United reimburses for canceled flights when the airline cancels or when major delays or significant changes occur, but the exact refund depends on the ticket type and circumstances.