Supplementary Credit Cards: What They Are and How They Work

By Dan Miller · July 18, 2022 · 7 minute read

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Supplementary Credit Cards: What They Are and How They Work

Adding supplementary credit cards — credit cards tied to a primary credit card account — can be a good way to help someone establish credit. For example, adding a supplementary credit card for a child can help them build credit, since they will get the benefit of the primary cardholder’s good credit history. Someone working to rebuild their credit could also benefit.

Still, it’s important to keep in mind that the primary cardholder is responsible for any charges made by any authorized users on the account. Read on to learn more about who can benefit from a supplementary credit card and the pros and cons of adding an authorized user to your account.

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What Is a Supplementary Credit Card?

A supplementary credit card, also known as an authorized user credit card, is a secondary credit card tied to the account of an existing user. This existing user could be a trusted friend, family member, or caregiver. The primary cardholder is responsible for all charges made by any authorized users or supplementary credit card holders.

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How Do Supplementary Credit Cards Work?

When you add a supplementary credit card to your credit card account, your credit card company will send a new physical card. The credit card issuer will typically mail the card to the address of the primary cardholder in order to prevent fraud.

In some cases, the supplementary credit card number will be the same as the card number of the primary credit card. In other cases, it may have a different number. Either way, all charges made on the account — including those made by supplementary cardholders — are the responsibility of the primary cardholder.

Supplementary Credit Card Annual Fees

For most credit cards, there is not a charge to add a supplementary credit card or authorized user. However, some premium cards, such as The Platinum Card from American Express, do charge an annual fee for additional cards.

Supplementary Credit Card Sign-Up Bonuses

Typically there is not a sign-up bonus or welcome offer for adding a supplementary card user. If you want to enjoy credit card bonuses, you must apply as the primary account holder.

Supplementary Credit Card Earnings and Redemption Rates

The earnings rates for supplementary credit cards are the same as the rates for the primary credit cardholder. Because the primary cardholder is financially responsible for all charges, they will receive the benefits of all rewards, regardless of which account makes the charges.

Who Needs a Supplementary Credit Card?

A supplementary credit card can be useful for someone who does not meet the credit card requirements to qualify for a credit card on their own.

For instance, you can get a supplementary card for a child to help them establish good credit. Adding them to your account also offers an opportunity for you to teach them the ins and outs of using a credit card responsibly.

You might also add a trusted friend or family member to your account to help them improve their credit score although this will depend on the primary cardholder keeping the account in good standing. Another reason you might add an authorized user to your account is to allow them to take advantage of travel or other benefits when you are not with them.

It’s also possible to add someone as an authorized user without actually giving them a card. This can allow them to enjoy the benefits to their credit score without the risk that they’ll overspend or otherwise use the card irresponsibly.

Pros and Cons of Supplementary Credit Cards

While there are benefits to supplementary credit cards, there are also downsides that are worth noting:

Pros of Supplementary Credit Cards Cons of Supplementary Credit Cards
Can help those with poor credit or no credit history to build or improve their credit score Primary cardholder remains financially responsible for all charges
Generally no annual fee to add a supplementary credit card Could damage the credit of the primary and/or secondary cardholder if used irresponsibly
Can earn additional rewards from the spending of multiple people Some cards may charge a fee to add an authorized user

Do Supplementary Credit Cards Affect Your Credit Score?

Yes, using a supplementary credit card can affect the credit score of both the primary and the secondary user. Depending on how a credit card is used, the effects could be either positive or negative.

If all cardholders on the account use their credit card responsibly, a supplementary credit card can have a positive impact on credit score due to how credit cards work. However, if the supplementary cardholder makes charges that the primary cardholder can’t repay, both of their credit scores could go down. Similarly, if the primary cardholder fails to make on-time payments, that could hurt the supplementary cardholder’s credit rather than helping it.

This is why it’s important that both cardholders are on the same page when it comes to credit card rules and best practices.

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How Much Do Supplementary Credit Cards Cost?

In most cases, there is no charge for adding supplementary credit cards or authorized user cards. However, some credit card issuers do charge an additional fee for adding supplementary cards. Make sure to check with your issuer before ordering one.

Applying for a Supplementary Credit Card

Because any supplementary credit cards are tied to the account of the primary cardholder, you can’t apply for a supplementary credit card directly. Instead, the primary cardholder will need to request an additional card directly from the issuer.

To do so, the primary cardholder can either call the customer service number listed on the back of their credit card or request an additional card through their online account.

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Alternatives to Supplementary Credit Card

Opening a supplementary credit card can be a good way to help a family member improve or establish credit, but it does come with some risk. One alternative to giving someone a supplementary credit card is to open a supplementary credit card account but keep the actual card.

With this arrangement, the authorized user gets the advantages of a supplementary account — namely, building their credit through the primary cardholder’s responsibly use — without the risk that they will use their card irresponsibly.

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The SoFi Credit Card

Supplementary credit cards, or authorized user cards, are additional cards tied to the credit card account of a primary cardholder. When used responsibly, they can help the authorized user build or establish credit. However, the primary account holder is responsible for all charges made by supplementary cardholders, so there is also some risk if the supplementary credit card is used irresponsibly.

The SoFi Credit Card offers unlimited 2% cash back on all eligible purchases. There are no spending categories or reward caps to worry about.1

Take advantage of this offer by applying for a SoFi credit card today.


Are bills paid with the card number of the primary or supplementary card?

The card numbers of the primary and supplementary cards are both tied to the primary cardholder’s account. As such, the primary cardholder is responsible for all charges made, including by authorized users.

Is a supplementary credit card the same as a joint card?

A joint credit card account allows two people to use the same credit card account, with both account owners holding responsibility for all charges made to the account. In contrast, a supplementary credit cardholder is not responsible for charges they make. Instead, only the primary cardholder is financially responsible for all charges made by any user.

Who is responsible for a supplementary credit card?

Only the primary account holder is responsible for charges made by any and all authorized users. Any secondary or supplementary cardholders are not considered financially liable for any charges they make.

Does a supplementary card affect credit score?

Yes, having a supplementary card can affect your credit score. It can help build or establish good credit when used responsibly. But because the primary cardholder is ultimately responsible for all charges, their credit could suffer if an authorized user uses the card irresponsibly. An authorized user could also see their score suffer if the primary account holder fails to manage their account responsibly.

Photo credit: iStock/MixMedia

Financial Tips & Strategies: The tips provided on this website are of a general nature and do not take into account your specific objectives, financial situation, and needs. You should always consider their appropriateness given your own circumstances.

Disclaimer: Many factors affect your credit scores and the interest rates you may receive. SoFi is not a Credit Repair Organization as defined under federal or state law, including the Credit Repair Organizations Act. SoFi does not provide “credit repair” services or advice or assistance regarding “rebuilding” or “improving” your credit record, credit history, or credit rating. For details, see the FTC’s website .

The SoFi Credit Card is issued by SoFi Bank, N.A. pursuant to license by Mastercard® International Incorporated and can be used everywhere Mastercard is accepted. Mastercard is a registered trademark, and the circles design is a trademark of Mastercard International Incorporated.

1See Rewards Details at

New and existing Checking and Savings members who have not previously enrolled in direct deposit with SoFi are eligible to earn a cash bonus when they set up direct deposits of at least $1,000 over a consecutive 25-day period. Cash bonus will be based on the total amount of direct deposit. The Program will be available through 12/31/23. Full terms at SoFi Checking and Savings is offered through SoFi Bank, N.A. Member FDIC.

SoFi members with direct deposit can earn up to 4.00% annual percentage yield (APY) interest on Savings account balances (including Vaults) and up to 1.20% APY on Checking account balances. There is no minimum direct deposit amount required to qualify for these rates. Members without direct deposit will earn 1.20% APY on all account balances in Checking and Savings (including Vaults). Interest rates are variable and subject to change at any time. These rates are current as of 3/17/2023. Additional information can be found at

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SoFi cardholders earn 2% unlimited cash back rewards when redeemed to save, invest, a statement credit, or pay down eligible SoFi debt.

1Members earn 2 rewards points for every dollar spent on purchases. No rewards points will be earned with respect to reversed transactions, returned purchases, or other similar transactions. When you elect to redeem rewards points into your SoFi Checking or Savings account, SoFi Money® account, SoFi Active Invest account, SoFi Credit Card account, or SoFi Personal, Private Student, or Student Loan Refinance, your rewards points will redeem at a rate of 1 cent per every point. For more details please visit the Rewards page. Brokerage and Active investing products offered through SoFi Securities LLC, member FINRA/SIPC. SoFi Securities LLC is an affiliate of SoFi Bank, N.A.


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