Joint credit cards explained

Add someone to your credit card and you're granting permission for them to spend up to your credit limit (they get their own card and PIN).

So, in the worst case, they could max out the card and leave you with the bill to pay – which could also lead to charges if they bust the credit limit and/or expensive interest on top if you can't clear the debt in full.

However, if you're comfortable with that risk, having the ability to add an additional cardholder can be useful. Here's a couple of examples: 

• Gets you both access to better and cheaper credit, if one of you has poorer credit. Joint credit cards could help where one person is finding it difficult to get approved for a credit card, or isn't eligible for the top deals.
  
  As only one person needs to be approved for the card, if one of you has better acceptance odds than the other, that person could apply and then add the other as an authorised used. 
  
  This also works if the poorer credit scorer has existing credit card debt, as certain cards allow you to shift your partner's debt to your card. So if you can get a better 0% balance transfer offer than them, this could help cut costs significantly. See full warnings and which cards allow this in transferring partner's debt. 
  
  However, this won't help improve or repair the credit history of the additional cardholder, as activity is only reported to the main cardholder's report. If this is what you're after, see credit cards for bad credit and how to improve your credit score. 
  
  
• Channels both of your spending to one card, which can max cashback and rewards. If you're debt-free and can afford to clear your credit card IN FULL every month, a top reward credit card that pays you to spend can be lucrative.
  
  These offer a variety of cashback, points and airmiles, often with large introductory bonuses if you spend a certain amount (for example, 20,000 reward points if you spend £3,000 in the first three months). There can also be extra perks or a better rate of rewards if you spend over a certain amount on the card each year (for example, 0.5% cashback up to £10,000/year spent, 1% above).  
  
  These should never be used as an excuse to overspend, but combining both of your spending could mean you're more likely to benefit from the best rewards.