Why can’t I pay for the extra baggage in advance?

You can pay extra bag charges in advance if all the flights in your ticket are marketed and operated by Finnair. If you are travelling on a flight operated by Finnair but your ticket has been issued by another airline, or your itinerary includes flight operated by another airline, please pay for your excess baggage at the airport. Please note that cash payments are not accepted for Finnair services at Helsinki Airport.