Aer Lingus will waive fees if customers want to change their flights from 3pm today.
Anyone who booked before March 6 for travel in March, April and May will now only have to pay the fare difference if they want to move their flights.
It comes as Irish people have been advised to avoid all non-essential travel to Spain as a result of the spread of the coronavirus.
In its second upgrade of the overall travel security status to the country in just two days, the Department of Foreign Affairs is now advising against all non-essential travel to any part of Spain - including the Balearic and Canary Islands.
A significant number of cases of Covid-19 have been confirmed in Spain. The highest incidences are in Madrid, Vitoria and Labastida in the Basque Country, Catalonia and the Rioja region.
"If you are in Spain, you should monitor developments regularly and follow the advice of local authorities. In what is an evolving situation, additional measures may be announced," said the Department.
Spain is the most popular tourist destination for Irish holidaymakers, with over two million Irish people flying there every year.