What is the least payment you can effectively transact in non-cash fiat?
What is the least payment possible for you? What is the least payment where the commission is less than rest of transaction? Please indicate the payment systems of the sender and recipient.
Not sure I understand this question's context but as a UK retail bank customer, electronic payments via BACS and Faster Payments, etc are free of charge even for sending a penny from normal current accounts.
I thought this was standard in modern banking systems!