Question:
What is Halacha regarding my Credit card that I let someone else use, and that one pays it back late, can he pay for the late fee and interest? (Can you kindly provide sources)
Answer:
When you let someone use your credit card , you are essentially taking a loan upon yourself from the credit card company, because you alone are the one liable to pay it. If you pay the credit card company late, then you are paying them ribbis, however if the company are not Jews it is permitted. Now when the person that borrowed the card pays your credit card bill, he is essentially paying you back for the loan that YOU gave him. Therefore when he pays the interest, he is paying your bill of interest for the loan that he took from you, which is ribbis. For example Levi used your card for $100, that means that you essentially lent him $100. Now that he is paying your credit card bill for you of $120 dollars, he is paying your bill for you because you gave him a loan, no different than if he paid your electric bill for you because you gave him a loan. Therefore it is very problematic. Either the person who owns the card should not collect the ribbis , or someone else should offer to give the owner of the card the ribbis. Please see the following post where this has beeen discussed. https://dinonline.org/2015/12/22/credit-card-interest-and-ribbis/