How do Supplementary Credit Cards Work?

**This post may contain affiliate links. I may be compensated if you use them.

Have you ever wondered how do supplementary credit cards work? Whenever you sign up for a new credit card, you’re always asked if you want to add a supplementary card or an authorized user credit card. Saying yes can be a great way for families to manage their finances, but are there any risks involved to be aware of? Of course, there are, which is why you need to understand how joint credit cards work before you add any users.

How do supplementary credit cards work?

Supplementary cards are pretty straightforward. The primary cardholder can add an authorized user to their account. That user could be a family member, caregiver, or even a friend. Although each additional card will have a unique credit card number, the account is managed by the primary user.

What that means is that when the monthly bill comes, it’s addressed to the primary cardholder. All purchases made by others users will be shown on the statement, but the primary user will be responsible for all the charges. There’s no denying that having authorized users can be handy since the main account holder can monitor purchases, but those extra cards could also be abused.

Generally speaking, you should never add a supplementary user unless they live with you and you trust them. If a friend ever approaches you to add them as an authorized user or to co-sign a card for them because they have bad credit, don’t do it, as you’d have to pay their bills if they don’t.

Supplementary card annual fees

When it comes to the supplementary credit card annual fees, consider it separate from the primary cardholder. If you have one of the best credit cards with no annual fee, you likely won’t have to pay an annual fee when you add a supplementary card.

However, if your credit card does come with an annual fee, then you’ll likely have to pay an annual fee for any supplementary credit cards that you add. The good news is that the annual fee of any supplementary card is usually lower than the fee that the primary cardholder pays, but you also need to consider any promotions available.

For example, the BMO World Elite Mastercard usually has a promo where the annual fee of $150 is waived for the first year. If you add an authorized user credit card, that would cost you an annual fee of $50 since the fee is not waived for the supplementary card.

That said, you don’t always pay a fee for the supplementary credit card. If you look at the Amex joint credit card fee for the American Express Gold Rewards Card, you can add one supplementary card for free which normally costs $50. Better yet, when you use a referral link to apply for the card, you also get an extra 5,000 American Express Membership Rewards points for free when adding a supplementary card.

As you can see, it’s important to know how do supplementary credit cards work so you don’t get caught paying fees you weren’t expecting. Don’t worry about having too many credit cards as it likely won’t matter if you’re managing your finances properly.

Supplementary card sign up bonuses

If you decide to add a joint credit card when you sign up for a new credit card, you won’t get double the sign up bonus even if you meet the minimum spend requirement with both cards. The good thing about supplementary credit cards is that the spending made on that card counts as overall spending if you’re trying to meet the minimum spend to get your welcome bonus.

Generally speaking, there’s no sign up bonus that you would get when you add an authorized user credit card, but as mentioned above, the Amex Gold Rewards Card does give supplementary cardholders a bonus when using a referral link.

That said, some credit card companies have experimented with offering a sign up bonus when you add a supplementary card. TD Bank had a promo recently which required you to sign up to get part of your welcome bonus. This was annoying since not everyone needs a joint credit card and there was a fee charged to the joint cardholder’s account. This is pretty annoying so I’m happy they haven’t used that tactic in a while. If they do bring it back, they should add a bonus like American Express.

Earn and redemption rates

When it comes to the earn rate with joint credit cards, it’s exactly the same for both cards. Let’s say you have the Marriott Bonvoy American Express Card. The earn rate is 5 Marriott Bonvoy points for every $1 spent on eligible purchases at participating Marriott Bonvoy properties and 2 points per dollar spent on all other purchases. It doesn’t matter if you’re the primary cardholder or you’re using the authorized user credit card, you both earn the same number of points.

Supplementary cardholders can not make redemptions directly. Since you’re pooling your miles and/or points, everything ends up in the primary cardholder’s account. This isn’t a big deal since the primary cardholder can just make a redemption on behalf of the joint cardholder. However, that could still pose a problem if you’re not travelling with the primary cardholder as your included travel insurance (with the exception of travel medical) wouldn’t be included. 

Do supplementary credit cards affect your credit score?

If you’re the supplementary card, there is no effect on your credit score at the time of application. The primary cardholder typically sees a decrease in their credit score of 10 points, regardless of how many authorized credit card users they add. This happens because a hard check is performed whenever you apply for new credit.

Although supplementary credit cardholders may like the idea of their credit card not affecting their credit score, it can actually work against them. Only the primary cardholder gets their credit history reported to the credit bureaus. If you’re the joint credit cardholder and you’re trying to build a credit history, you wouldn’t be able to do it. You’d be better off applying for a credit card where you’re the primary cardholder.

Credit card debt

Ultimately, any credit card debt incurred by the supplementary cardholder is the responsibility of the primary cardholder. In theory, the authorized user’s credit card could rack up a huge amount of debt and have no worries. Of course, you wouldn’t want to do that since presumably, the primary cardholder is someone you’re tight with.

On the flip side of things, the primary cardholder should think hard before they add supplementary credit cards. If it’s your partner, child or caregiver, you’re probably fine, but you don’t want to add a friend who has problems getting their own credit card.

Cardholder benefits

Just because you have a supplementary card, that doesn’t mean you’re automatically entitled to the benefits that the primary cardholder gets. To make things more complicated, every credit card has different rules about the benefits that authorized users get, so you need to read the fine print. For example, the American Express Platinum Card clearly states that joint cardholders get the following benefits:

  • The American Express Global Lounge Collection
  • Platinum Concierge and Global Dining Collection
  • Toronto Pearson International Airport Benefits
  • Hertz and Avis Car Rental Benefits
  • Platinum Card Travel Service
  • American Express Invites
  • Travel insurance

The one major benefit that they don’t get which the primary cardholder does get is the annual $200 travel credit. This should be obvious since the annual fee for the secondary card is $175, but you’d be surprised how many people assume they still get it.

Now, if you look at the Scotiabank Passport Visa Infinite Card’s welcome kit, you might be surprised to learn that the Priority Pass Membership and six free annual lounge visits don’t apply to the supplementary cardholder. Many people don’t expect six free passes to be given to both the primary and supplementary cardholders, but sometimes people are shocked to learn that the secondary cardholder can’t use any of the lounge passes unless the primary cardholder is present.

Should you get a supplementary credit card?

If you’re looking to pool your points or you want to give someone access to credit, then it definitely makes sense to have a supplementary card. That said, you shouldn’t just sign up right away. First, check to see if there’s an annual fee. If getting a joint credit card is free, then it doesn’t hurt. That said, remember, the supplementary user doesn’t build their credit score with a joint credit card.

It’s also worth paying attention to what the card offers. As mentioned, some cards share the benefits, but quite often people are more interested in the earn rate. If you can have multiple people in your family pooling their points into one account, it definitely benefits you. For example, one ideal credit card to get supplementary credit cards is the American Express Cobalt Card. There’s no annual fee for additional cards, the earn rate is high, and the American Express Membership Rewards points you earn are incredibly valuable.

American Express Cobalt Card

  • $12.99 Monthly fee ($155.88 yearly)
  • 1,250 monthly points when charging $750 each month for a year (15,000 points total)
  • Earn 5 points per $1 spent on eats and drinks
  • Earn 3 points per $1 spent on streaming services
  • Earn 2 points per $1 spent on travel
  • Earn 1 point per $1 spent on all other purchases

About Barry Choi

Barry Choi is a Toronto-based personal finance and travel expert who frequently makes media appearances. His blog Money We Have is one of Canada’s most trusted sources when it comes to money and travel. You can find him on Twitter:@barrychoi


  1. Clevy on April 11, 2022 at 6:04 AM

    question when, paying the bills of the supplementary card do you pay it using the card number of the supplementary card or you can pay it using the primary card number ?

    • Barry Choi on April 11, 2022 at 6:14 AM

      Hi Clevy,

      You would pay the primary cardnumber.

  2. susana.carpenter on May 27, 2022 at 9:33 PM

    If the primary card holder dies, is the secondary holder obliged to pay the debt?

    • Barry Choi on May 28, 2022 at 6:53 AM


      As long as you were a supplementary user and not a co-signer, you’re not responsible for the debt.

  3. susana on May 28, 2022 at 2:33 PM


  4. Valentin on July 28, 2022 at 11:15 PM

    If you add a supplementary cards that is of a different credit card, does the supplementary card also earn it’s welcome bonus?

    • Barry Choi on July 29, 2022 at 6:07 AM


      No, the supplementary user does not get a separate welcome bonus, but their spending counts towards the primary cardholder’s minimum spend requirement to get their bonus.

      • L Allen on April 17, 2023 at 5:13 PM

        What you don’t mention is what happens if you want to cancel the supplementary card. Amex will require you to close the account. If you hold more than one card with them then you should be able to transfer your points across and not lose them. However, it’s something to be aware of.

Leave a Comment

Get a FREE copy of Travel Hacking for Lazy People

Subscribe now to get your FREE eBook and learn how to travel in luxury for less