How card issuers earn money, and why your own rewards, interest and fees are what count

The short answer

Paying in full and collecting rewards raises a fair question: what does the bank get out of it? The issuer, the bank behind your card, has several sources of revenue. Merchants pay to accept the card, people who carry a balance pay interest, and particular activities carry fees. None of those figures is the issuer's profit, because its costs include funding, rewards, servicing, fraud and credit losses.

Julia does not try to work out the bank's profit. She looks at what she can measure on her own statement: the rewards she received, the fees she paid, the interest she was charged and any spending she would not otherwise have made. In her example, $360 of rewards stops looking impressive once $400 of interest and a $95 annual fee are added.

Where the money from one purchase goes

Take an $80 purchase. If the merchant pays $2.40 to accept it, the merchant receives $77.60, a 3% acceptance cost for this sale. Julia uses that figure for the example only. The actual charge depends on the merchant and the transaction.

The bank does not automatically keep the whole $2.40. If the card earns 2% on that purchase, the reward is $1.60, and subtracting it from the merchant's charge still does not reveal the bank's profit. It would leave out the other businesses and costs involved.

A common arrangement has 4 main participants: you, the merchant, the merchant's acquiring bank and the bank that issued your card. A network connects them and sets rules, and processors may help handle the payment. Some systems combine these roles, so not every transaction works exactly this way. You do not need to memorize the names. Just keep the issuer separate from the other businesses that help accept and process the payment.

Merchant pricing can include interchange, network charges and acquiring or processing services. Interchange compensates the issuer within that system, and the other participants have their own charges and arrangements. The amounts depend on the transaction, the card, the merchant and the contract. So if a store's processing quote says 3%, that does not mean your bank earns 3% in profit.

Interest and fees

Even when you pay in full, your purchases can generate revenue for the issuer. Interest-bearing balances add another source, with their own costs and risks. When someone carries a balance, they are paying to borrow under the card agreement, and the APR and the balance method determine the charge. Interest matters to issuers, but a large interest bill does not tell you which customer is most profitable once losses and costs are counted.

Fees are a further source, and the type of fee tells you which activity to check:

• An annual fee is a charge for holding the account or its package of benefits.
• A balance-transfer fee applies to moving eligible debt.
• Cash-advance fees apply to a different kind of borrowing.
• Late fees and foreign-transaction fees have their own conditions.

"No annual fee" removes one possible charge. It does not mean every way of using the account is free.

Take a card that earns 2% on an eligible foreign purchase but charges a 3% foreign-transaction fee. On a purchase equivalent to $900, Julia would earn $18 and pay a $27 fee, leaving her $9 behind from the fee and reward alone. A separate conversion markup or interest would be additional. So a card with no foreign-transaction fee may be more useful abroad, even if another card earns slightly more at home. Looking only at the reward rate would give the wrong answer.

Add up your own year

Julia's annual summary shows $360 in rewards, $400 in interest and a $95 annual fee. Put together, the interest and fee exceed the rewards by $135. The rewards screen may emphasize the $360, but a budget has to include the interest and the fee as well.

If having the card also led you to buy extra things, include that spending when judging whether it helped. The honest question is not what the bank made. It is what the card actually cost you.

Offers and credits

Welcome bonuses and promotional rates fit into this business too, because issuers want to attract accounts and spending. A bonus can work well when the qualifying purchases were already planned and affordable. It becomes a different deal if you buy extra just to qualify.

A 0% transfer offer can also help. Compare its fee and repayment schedule with your alternatives. The offer does not mean the debt will be gone before the regular rate starts, so put the expiration date into the payoff plan. Premium-card credits need the same review: the advertised maximum is not automatically the amount you will save. Your value depends on what you use, the prices and restrictions, and what you would have bought anyway.

Julia treats a shopping offer in an app the same way. Say it gives $15 back after spending $90. That might be useful for a purchase she had already planned. If she only needed $55 of supplies, adding another $35 just to qualify would leave her spending $20 more after the credit. The offer could encourage more card use while staying optional for her, so she decides from her shopping list before looking at the reward. That way the bank's invitation does not quietly become the family's spending plan.

What a receipt does not show

A merchant has a real acceptance cost, but that does not tell you exactly how it sets prices. How a particular merchant absorbs that cost or passes it on depends on its pricing and its market. You cannot assume a precise rewards surcharge is built into every receipt, and you cannot assume it comes back to you dollar for dollar.

Before you act

Julia's Wallet Check stays on what she can measure: rewards received, fees paid, interest charged and spending she would not otherwise have made. The recurring value in a Wallet Score follows the same idea, counting benefits that replace stated expenses and deducting the costs. She does not make costing the bank money a goal. She cannot see all of its costs, and a complicated strategy could waste her own money or time. She would rather choose an account that suits the purchases and payments she already needs to make.

At your next review, put rewards, interest and fees on the same page. On the issuer's page, check the APR and how the balance is calculated, each fee that could apply, the end date of any promotional rate and the conditions on any credit or offer. The figures here are Julia's worked examples. No card record sits behind this lesson, so it carries no verification date; confirm current terms with the issuer.