If one has permission to use another person’s credit card. when one purchases something. is it viewed as the credit card owner purchasing and then the second person purchasing it from them? or is it viewed as a double loan once from the credit card company and and then from the person loaning the card?
It is viewed as a double loan, the credit card owner is borrowing the money from the credit card company, and he in turn is lending it to his friend. This fact has numerous, halachic ramifications regarding hilchos ribbis. A person that takes a loan on someone else’s credit card, which will be paying interest, has a serious ribbis issue, because even if the credit card company is a gentile, and it is permitted for the Jew to pay then the interest. The Jew may not in turn ask his friend for the interest payments, because that is ribbis! A person that will let his friend use his credit card for such a use must make a proper heter iska first. Additionally one may not pay his friend for using his credit card, since it is paying him for a loan that he was given. Please see the following links https://dinonline.org/2019/06/03/ribbis-with-credit-cards/ and https://dinonline.org/2018/06/15/credit-card-and-ribis/