Originally Posted by GUWonder

A lot of US banks, Citibank included, charge account holders a fee per withdrawal from another banks' ATM, even when the ATM-operating bank does not charge a fee to the ATM cardholder. So while the UK banks won't be charging the Citibank US cardholder for the withdrawal, Citibank US often still does charge an international out-of-network withdrawal transaction fee.

Being milked by one's own bank does get frustrating, but there is a bit of comfort to be got by knowing that the bank ATMs in the UK don't charge fees themselves, but that requires changing banks in the US or some other modifications. One modification some use is to transfer funds from a Citibank account to a Paypal account since the ATM fees are generally lower for Paypal withdrawals overseas than they are for most Citibank US customers withdrawing money overseas from non-Citibank ATMs.