Let's say I know a credit card number and the card doesn't belong to me, can I deposit money on that credit card? The receiver will not object getting extra money. But is this possible and how you do it? Let's assume that the credit card is Mastercard, in case there are different practices with other cards.
A credit card is not a bank account. It is, essentially, a contract to extend a line of credit on an as needed basis through a process accepted by the provider(purchase through approved vender, cash advance, etc). There is no mechanism for the bank to accept or hold a deposit. While most card issuers will simple retain the money for a period of up 30-60 days to apply toward transactions, I have had a card that actually charged a fee for having a negative balance in excess of $10 for more than 30 days(the fee was $10/month).
So no you can not DEPOSIT money on any credit card. You need an account that accepts deposits to make a deposit.
Is this a hypothetical question? It sounds like a combination of "can my amount owed on a card go negative (i.e. a credit) and can I deposit to someone else's XXX account. My wife kept her last name. when I pay her charge card I've never gotten rejected, I don't see why this wouldn't work if a stranger gave me their number and address to make payment.
JohnFx is more experienced than I am but I have paid off friends cards before. It was as simple as asking them the routing number of the bank that gave them the card and setting up an ACH with their card number.
I guess this might be against some banks T&C but the CU I used to carry out the ACH gave me the go ahead as long as I did not dispute the payment later.