> Contrary to what many believe, SEPA transfers are not entirely free. Sure, most banks do not charge for SEPA transfers, but some banks still do. When there are charges, you pay the same price for a SEPA transfer as you would for a domestic wire transfer. Regulation 924/2009 mandates banks to apply the same charges to cross-border euro transactions as they do for domestic transfers. Banks are prohibited from levying different charges based on the recipient bank's location. Therefore, if your bank in France charges you nothing for making transactions within France, then you will also pay nothing for euro transfers to Portugal, for example.

https://www.quanloop.com/en/investing/are-sepa-payments-real...

I was unable to find out what the cost to banks was, but it's possible there is one and it's covered by the monthly fees that European banks charge, which are relatively rare in the US.