Cash back can feel like the issuer giving money away. It is not. Understanding where the money comes from explains almost every rule in a rewards program.
Where the money comes from
Every card transaction carries an interchange fee, paid by the merchant and set by the card network. A portion goes to the issuing bank. Rewards are funded largely out of that share, supplemented by annual fees and interest income.
This explains several things at once. It is why merchants sometimes offer a discount for cash. It is why debit card rewards are rare — debit interchange is regulated and much lower. And it is why earning rates cluster in a narrow band: they are constrained by what interchange can support.
It also explains the exclusions. Transactions that generate little or no interchange generally earn nothing.
What does not earn
- Cash advances and cash-equivalent transactions
- Balance transfers
- Fees and interest charged by the issuer
- Payments made to the card itself
- Most gambling and lottery transactions
- Some tax and government payments, depending on the program
Program terms vary and are stated in the rewards agreement. If a category matters to you — large tax payments, for example — confirm before assuming.
How categories are decided
Bonus categories are assigned by merchant category code, a classification the merchant's payment processor applies to the business, not by what you bought.
This produces predictable frustrations. A supermarket inside a superstore may code as a discount store rather than a grocer. A restaurant inside a hotel may code as lodging. A wholesale club typically codes as a club, not as groceries.
When rewards post
Most issuers credit rewards when the transaction settles — typically one to three business days after purchase — though some post at the end of the billing cycle.
Returns reverse the rewards. Return a $200 purchase that earned $6 and the $6 is deducted. If your rewards balance is too low to absorb it, most programs carry a negative balance until you earn it back.
Caps, tiers and thresholds
| Limit type | How it works | What to watch |
|---|---|---|
| Quarterly cap | The bonus rate applies up to a spending limit each quarter | Spending beyond the cap usually drops to the base rate |
| Annual cap | A yearly ceiling on bonus-rate spending | Front-loaded spending can exhaust it early |
| Activation requirement | Rotating categories must be enrolled each quarter | Missing enrollment forfeits the entire quarter |
| Redemption minimum | A threshold before rewards can be redeemed | Small balances can sit unusable for a long time |
Redemption
The most common options are a statement credit, a direct deposit to a linked bank account, a check, or a purchase credit applied against a specific transaction.
Statement credits reduce your balance but do not count as a payment. If your statement balance is $500 and you apply $50 of cash back, you still owe the minimum payment — the credit does not satisfy it. This catches people every year.
Watch for redemption options that pay more than face value, such as gift cards at a discount, and for those that pay less. Redeeming a dollar of cash back for less than a dollar is a straightforwardly bad deal no matter how it is presented.
