Can I use someone else's credit card if they let me?

You certainly can’t use someone else’s credit card without permission. That’s fraud, which is a crime. And you technically aren’t allowed to use a credit card that isn’t your own under any circumstances. But in reality, you shouldn’t run into any problems if you’re using a friend’s or family member’s credit card with their permission. That’s especially true if you’re the same gender.

Most merchants simply don’t compare the names on their customers’ IDs and credit cards to confirm they match. A credit card whose signature panel is unsigned or reads, “See ID,” might arouse some suspicion, though. And the merchant could request identification as a result. But merchants are not allowed to decline transactions due to a lack of ID when the card is signed.

It’s a similar story for a child using a parent’s credit card with permission. Many children have credit cards, as issuers generally don’t have minimum age requirements for authorized users. And it’s fairly common for a parent to send their child into a store or restaurant to pay for a purchase with their credit card. So merchants can’t be too suspicious. But context matters in this case, too. If a merchant has reason to believe a youth is using a credit card without permission, they might ask for ID.

You also have to remember that letting someone else use your credit card could wind up being pretty costly. Since you’re giving that person permission to make purchases, you’re on the hook for what they spend. But you should be fine as long as you choose whom to lend your card to wisely, establish firm ground rules and regularly monitor your account.

At the end of the day, it’s not illegal to use someone else’s credit card with permission. But doing so does violate card network rules. Anytime your credit card is out of your direct control, it is theoretically more susceptible to fraud. You don’t absolutely know how it’s being used. And the credit card company didn’t approve your friend or family member for an account. They approved you. Plus, if fraud ever crops up on your account, it will be more difficult to determine whether the charge was authorized.

With that being said, there’s a viable, above-board alternative to sharing your physical credit card – though it applies more to family members than friends. Making a relative an authorized user on your credit card will give them spending privileges as well as help them build credit.

You can use someone else's credit card if they let you. But if they don't give you permission, it's fraud - and that is a crime. If the card owner reports that card as being stolen or fraudulently used, the authorities will begin an investigation. And since all cards come with $0 fraud liability, the card owner may be reimbursed for the unauthorized charges after the investigation is complete.

The issuer only authorized the person who got approved for the card to access its credit line. So even using someone else's card with permission is a violation of that card's terms. In that case, the cardholder is liable for any charges you make.

A perfectly legal way to use someone else's credit card with permission is to ask the card's owner to add you as an authorized user.

If someone else's adds you to the account as authorized user, yes. If someone else lends you his/her credit card he/she would be breaking their agreement with the credit card company. 

Technically, it would be against terms and conditions to use someone else's credit card, even if you've got the PIN. That being said, they can't ask for identification if the card is signed. If it's not signed, they are allowed to ask for it, but it's not required or anything.

It's against the terms of service. You might get away with it in most cases, but I would make sure I had it in writing that I'm using the card with the owner's permission.