<prompt> Human: My friend just was approved for the Chase Sapphire Preferred credit card. If he adds an authorized user, he receives an additional 5,000 miles. How can this affect my credit? He hasnt had a late payment for any of his debt, but does carry a balance on them fairly often.  <response>: How can this affect my credit? He hasnt had a late payment for any of his debt, but does carry a balance on them fairly often.It will affect your credit historyscore, for better or worse, depending on how both you and your friend utilize the credit card. However, authorized users are not responsible for any credit debt from that particular card as opposed to joint account users, so your friend must have a lot of faith in you not to run up his card and leave him high and dry. 