A 0% APR credit card offer looks like a subsidy from the bank to the cardholder. It is not. The bank still collects money on every transaction, just from a different source than interest.
The misconception is that revenue requires interest payments. In reality, credit card issuers have three primary income streams: interchange fees, balance-transfer fees, and interest. A 0% APR promotion eliminates the third stream temporarily but maximizes the first two.
The mechanism
Every time a card is swiped, the merchant pays a processing fee to the payment network (Visa or Mastercard). A portion of that fee goes to the bank that issued the card. This is the interchange fee.
According to data from the Consumer Financial Protection Bureau, interchange rates typically range from 1.5% to 3% of the transaction amount. The bank keeps this money regardless of whether the cardholder pays interest on their balance. When a user takes a 0% APR offer, the bank sacrifices interest income but gains volume. More volume means more interchange fees.
Additionally, banks charge upfront fees for balance transfers. These are usually 3% to 5% of the transferred amount. This fee is collected immediately, before the 0% period begins. It is not deferred interest; it is a service charge for moving debt to a new account.
The math, with real numbers
Consider a standard 18-month 0% APR balance transfer offer. The scenario involves a $10,000 transfer and consistent monthly spending. The bank collects fees on both the transfer and the new spending.
Assume the following terms:
- Balance transfer fee: 3% of the principal.
- Interchange rate: 2% average on new purchases.
- Monthly new spending: $300.
- Promotion length: 18 months.
The revenue calculation breaks down as follows:
| Revenue Source | Calculation | Total |
|---|---|---|
| Balance Transfer Fee | $10,000 × 3% | $300.00 |
| New Spend Volume | $300 × 18 months | $5,400.00 |
| Interchange Revenue | $5,400 × 2% | $108.00 |
| Total Revenue | Fee + Interchange | $408.00 |
The bank earns $408.00 over 18 months without collecting a single dollar of interest. This revenue helps cover the cost of capital and acquisition. While the bank may spend more than $400 to acquire a new customer, this revenue stream offsets the cost of funds and contributes to the account’s lifetime value.
When the rule of thumb breaks
The 0% offer is not risk-free for the bank. Two conditions change the revenue model significantly.
First, missing a payment triggers a penalty APR. Under Visa and Mastercard network rules, issuers can raise the APR to 30% or higher if a payment is 60 days late. This resets the revenue stream from fees to high-interest charges. The 0% benefit is revoked, and the bank recovers its costs through penalty interest.
Second, the balance transfer fee caps the revenue. If a user transfers $1,000 instead of $10,000, the fee revenue drops to $30 (at 3%). The interchange on $300/month remains $108. The total revenue becomes $138. This is often insufficient to cover the cost of servicing the account. Banks prefer large transfers because the fixed cost of account maintenance is spread over higher fee revenue.
Finally, closing the account early stops the revenue. If a user pays off the $10,000 in month 6 and closes the card, the bank collects the $300 fee and roughly $36 in interchange. The 18-month revenue projection of $408 never materializes. This is why banks encourage users to keep the account open by offering rewards points on new spending, ensuring the $300 monthly spend continues even after the transfer is paid.
The summary
Banks generate revenue on 0% APR cards through fees, not interest.
- Balance transfer fee: Collects 3% upfront (e.g., $300 on a $10,000 transfer).
- Interchange fees: Collects ~2% on new spending (e.g., $108 on $5,400 over 18 months).
- Total revenue: Approximately $408 over the promo period without interest income.
The bank makes money on the transaction volume and the fee structure, not the interest. The 0% APR is a tool to capture spending volume that would otherwise go to a competitor. For the cardholder, the offer is beneficial if the fee is lower than the interest saved elsewhere. For the bank, the offer is a revenue shift from interest to interchange. The math shows $408 in revenue on a $10,000 transfer with $300 monthly spending, proving the bank profits even when the rate is zero.