Piggybacking is the act of improving your credit score or rating by becoming an authorized user on someone else’s credit card. By doing this, the authorized user receives a spillover of benefits of the main accountholder’s good credit. It is most often used by parents with their children or with spouses. For piggybacking to work, the “good credit” person must add the “bad credit” or “no credit” person as an authorized user, not the other way around.