On this page
“Earn 10% above $100” can describe two different calculations. One applies 10% to the entire eligible basket once the threshold is reached. The other applies 10% only to the portion above $100, leaving the first $100 at a lower rate. The same words can therefore produce very different rewards.
A tiered offer should state both the rates and the part of the basket each rate affects. Testing amounts immediately around the boundary reveals whether the higher tier creates a jump or a gradual increase.
Define whole-basket and marginal bands
Use a fictional reward with a 5% lower rate and a 10% higher rate around a $100 boundary. For the whole-basket design in this example, eligible baskets below $100 earn 5%, while baskets of $100 or more earn 10% on the entire eligible amount.
For the marginal design, the first $100 earns 5%, and only the portion above $100 earns 10%. At exactly $100, the reward is therefore $5. The higher rate begins affecting only additional spending beyond that amount.
These are original arithmetic designs for comparison, not RebateCardX configuration instructions. The merchant should select the intended behavior and then confirm support through the approved campaign discussion.
The distinction is similar to asking whether reaching a new band changes the treatment of earlier spending within the same basket. A whole-basket tier does. A marginal tier does not. Avoid describing either simply as a “better tier” without specifying the monetary effect.
Calculate values around the boundary
For clarity, retain unrounded amounts in the comparison and show final examples rounded to cents once at the order level, using ordinary nearest-cent rounding for these positive values.
| Eligible basket | Whole-basket calculation | Whole-basket reward | Marginal calculation | Marginal reward |
|---|---|---|---|---|
| $99.99 | $99.99 × 5% | $5.00 | $99.99 × 5% | $5.00 |
| $100.00 | $100 × 10% | $10.00 | First $100 × 5% | $5.00 |
| $100.01 | $100.01 × 10% | $10.00 | $5 + $0.01 × 10% | $5.00 |
| $120.00 | $120 × 10% | $12.00 | $5 + $20 × 10% | $7.00 |
| $180.00 | $180 × 10% | $18.00 | $5 + $80 × 10% | $13.00 |
At the boundary, the whole-basket example jumps from an unrounded $4.9995 to $10. The marginal example moves from $4.9995 to $5. The rates are the same, but the earning curves are not.
For every basket at or above $100 in this particular comparison, the whole-basket design provides $5 more than the marginal design before any separate cap. That difference comes from applying the extra five percentage points to the first $100: $100 multiplied by 5% equals $5.
The one-cent-above row is also useful. Both displayed marginal amounts round to $5.00 even though the unrounded reward increases by one tenth of a cent. Rounding can hide a small continuous change; it does not turn the marginal design into a whole-basket tier. Keep the conceptual rule separate from display precision.
A difficult case arises when the merchant writes “over $100” but implements “$100 or more.” Those phrases treat the exact boundary differently. Under the whole-basket design, that one distinction determines whether a $100 basket receives $5 or $10. The specification must name the inclusive or exclusive boundary rather than relying on casual wording.
Another case is a second higher band. The same question repeats: does reaching it reprice the entire basket, or only the next portion? A multi-band table should preserve one explicit method unless the merchant deliberately designs a more complex formula. Mixing methods without a clear reason makes the offer harder to explain.
Choose the tier behavior the offer will promise
If the merchant wants a visible step-up benefit when a basket reaches a defined amount, a whole-basket tier expresses that intention. If it wants additional spending to earn a higher rate without repricing earlier spending, a marginal design expresses that intention. The choice should reflect the desired value pattern, not a misunderstanding of the phrase “10% above $100.”
For the fictional campaign, a marginal decision note could read: “The first $100 of eligible value earns 5%. Eligible value above $100 earns 10%. A $120 basket therefore earns $7 before any separately defined adjustments. Reaching the higher band does not change the rate on the first $100.”
A whole-basket note would instead state that a basket of $100 or more earns 10% on its entire approved eligible amount. Attach the boundary table so the customer-facing description and internal amount model can be checked against the same outputs.
Do not confuse these spend bands with customer loyalty status. This article assumes a single approved basket and asks how its value is divided or repriced. A customer segment might influence which offer is available, but that is a different decision from the arithmetic within this offer.
Test whether the team can explain the $120 marginal example without saying the customer has reached a 10% reward on everything. The first $100 contributes $5 and the remaining $20 contributes $2. The combined $7 is approximately 5.83% of the whole basket. That effective percentage is an outcome of the mix of bands, not a new rate to insert into the next calculation. This distinction becomes increasingly important when the offer contains several marginal bands and the customer compares a headline upper rate with the actual total.
The practical result is an agreed earning curve with exact boundary behavior. Anyone reviewing a $99.99, $100 or $120 basket should be able to calculate the reward and explain why it changes. That is the level of precision a tiered promise needs before it becomes campaign copy or implementation work.
Review how higher spending bands should change the reward in your campaign. Discuss program fit.
Source references
This guide is general information, not financial, legal, tax or regulatory advice. Eligibility, card availability, permitted use and responsibilities depend on the applicable offer and card terms.