Aer Lingus allows flight date changes up to two hours before departure, subject to fare type and availability. Change fees vary: Saver and Plus fares incur a fee plus any fare difference, while Advantage, AerSpace, Smart, Flex, and Business fares may only require the fare difference. Changes must be made from the same country of origin, and all travel must be completed within one year... https://americanairtravel.com/aer-lingus-flight-date-change-policy/