Every business card pitch comes down to one choice: a simple flat rate on everything, or a higher rate on a few categories and a lower rate on the rest. Neither is better in general. Which one wins depends on how your own spending is split, and on whether the category card charges an annual fee. This guide shows how to work that out with real arithmetic you can repeat in the calculator.
A flat-rate card pays the same percentage on every purchase. If the rate is 2%, then $1,000 of spending returns $20, whether it was fuel, software or a one-off equipment purchase. There is nothing to track and nothing to cap out.
A category card pays a higher rate (the "bonus" rate) on specific kinds of spending, such as travel, dining, office supplies or online advertising, and a lower "base" rate on everything else. The headline number is attractive, but you only collect it on the portion of your spending that falls inside the bonus categories.
Take the same spending profile used on the calculator's home page. The business spends $500 a month on travel, $300 on dining, $800 on office supplies and software, and $600 on online advertising. Those four add up to $2,200 a month, or $26,400 a year of bonus-category spending. Another $1,200 a month, or $14,400 a year, goes to payroll services, rent, insurance and miscellaneous vendors. Total annual spending is $40,800.
Now compare two hypothetical cards. These are invented for illustration and are not any real product.
| Step | Card A (flat) | Card B (category) |
|---|---|---|
| Rate structure | 2% on everything | 3% bonus, 1% base |
| Annual fee | $0 | $95 |
| Rewards on $26,400 bonus spend | $528 | $792 |
| Rewards on $14,400 other spend | $288 | $144 |
| Gross rewards | $816 | $936 |
| Net after annual fee | $816 | $841 |
For this profile, the category card comes out $25 ahead per year. That is a small margin for a card that needs more attention to use well, and it is worth asking whether $25 justifies the extra tracking.
The margin depends heavily on how much of your spending lands in the bonus categories. Write the share of bonus spending as s and total annual spending as T. Card B earns T × (0.03s + 0.01(1 − s)) − 95, while Card A earns 0.02 × T. Setting them equal with T = $40,800 gives s of about 61.6%. In plain words: Card B only wins if more than roughly 62% of your total spending falls in its bonus categories. In the example above the share is 26,400 / 40,800 = 64.7%, which is why B edges ahead.
Now change the profile. Suppose a different business has the same $40,800 total, but only $12,000 a year in bonus categories and $28,800 everywhere else. Card B pays 12,000 × 0.03 = $360 plus 28,800 × 0.01 = $288, for $648 gross and $553 net after the fee. Card A still pays $816. The flat card wins by $263. Same cards, same total spending, very different answer.
A flat card has one hidden advantage: it keeps paying when your business changes. If you stop running ads next year or take fewer trips, a category card quietly loses its edge, while a flat rate does not care. If your spending is stable and concentrated, a category card can be worth the attention. If it moves around, simple is often safer. The calculator does not make that call for you; it only shows the arithmetic so that you can.