Ticketmaster has confirmed the process of refunding Garth Brooks ticket holders is now under way.
A spokesman for the company said customers who bought tickets via credit card will have their money refunded automatically, but said it will take seven to ten working days for that money to appear in their accounts.
Customers who bought at Ticketmaster outlets can download a refund form, or collect one from an outlet, and post the form back with the ticket or return it to the outlet.
A full refund including service charges will be processed by bank transfer within 21 days of receiving the form and tickets.
People who purchased tickets from unauthorised ticket sellers will need to contact that ticket seller to obtain a refund.
Ticketmaster has said the scale of the refund operation is unprecedented.
A last-ditch attempt to save the five Croke Park concerts failed last night.
Dublin City Council did not agree to allow an uncontested High Court action to overturn its decision in relation to the concerts.