Delta Air Lines said Wednesday it will extend through 2023 the window for customers to rebook credits earned when they purchased but then canceled flights during the pandemic.

Before the announcement, Delta flight credits were set to expire at the end of 2022. The new date will also apply to all tickets bought in 2022. Customers will be able to use the credits throughout 2024 if the trip is booked by Dec. 31, 2023, the airline said.

The move was not immediately matched by American Airlines or United Airlines, where credits are set to expire March 31 and Dec. 31, respectively.

Passengers are entitled to refunds under federal law if the airline cancels their flight. But if the passenger cancels, airlines generally provide only some form of credit or voucher, typically with a one-year expiration.

Refunds have become a major source of airline consumer complaints to the U.S. Transportation Department. Congress is considering legislation that would require airlines to cover lodging, meals and other costs that consumers incur when airlines cancel their flight.