If you want to add somebody as a co-signer, consider Discover credit cards. Credit scores for both the cardholder and co-signer will be reported on both credit histories. But remember, if you add someone as a co-signer and anything goes wrong, you will be liable for the balance, interest, and penalty fees. Authorized users have permission to use a credit card but are not financially responsible for the account. This means that the authorized user is not liable to pay the debt, interest, or penalty fees. However, the account information will be reported on the authorized user’s credit history.