There are two ways to share a credit card account with another person:
You can be an authorized user or a joint account holder.
The liability for the payments differs greatly.
“Authorized users are entitled to use the credit extended to the card holder, but have no legal responsibility to pay the bill.”
Joint account holders, on the other hand, actually share ownership of the account and both are liable for repaying the debt.
A joint account must be opened by the account holders at the same time. It’s literally like a joint liability account.
The advantage is that both credit histories get updated, and both account holders are legally responsible for the debt.