Adding an authorized user to a cash back credit card allows that person to make purchases on the account and have those purchases earn cash back under the primary account's rate structure, without the authorized user needing their own credit application or credit check.
This is a commonly overlooked strategy for households where a spouse, adult child, or family member makes regular purchases -- consolidating that spend onto a single well-optimized card captures the bonus rate on every dollar spent across the household, rather than splitting spend across multiple lower-rate cards.
For category-specific cards, this consolidation can be particularly valuable: if one household member does most of the grocery shopping and another does most of the gas purchasing, having both as authorized users on a card with strong bonuses in both categories captures both bonuses under one account rather than needing two separate optimized cards.
Authorized user relationships also matter for credit-building purposes independent of cash back, since the primary account's payment history and utilization often reflect on the authorized user's own credit profile -- though this is a secondary benefit, not the primary reason to consider the strategy for reward optimization.
The main consideration before adding an authorized user is trust and shared spending visibility, since the primary account holder remains fully liable for all charges made by every authorized user on the account, regardless of who benefits from the resulting cash back.
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Some cards charge a small annual fee per authorized user, though many no-fee cash back cards add authorized users at no additional cost.
Yes -- the primary account holder is fully responsible for all charges regardless of which authorized user made them.