Legal-liability standards this lesson follows
Authorized user: federal CFPB guidance says authorized-user status generally does not itself obligate the person to repay the account debt. Specific agreements and applicable law can matter.
Co-signer / guarantor: a co-signer can be legally obligated to repay if the primary borrower does not. Credit-card rules for young consumers also recognize written consent by co-signers, guarantors and joint accountholders who accept liability.
Permission to use your card: if you voluntarily give someone the card or authority to use it, later charges may still be treated as authorized until the issuer is told that person is no longer authorized. Do not describe an over-budget family charge as “fraud” automatically.
New account opened without permission: that can be identity theft. FTC and IdentityTheft.gov provide formal reporting, blocking and dispute procedures.
State-law caution: contract liability, agency/authority questions, marital-property rules and collection remedies can vary by state. This article explains general federal consumer-credit principles and does not determine liability in an individual dispute.