Interactive tool · works year-round
Cashback stacker: what card + portal + rebate really earn together
A 2% card, a 5% shopping portal and a 10% rebate do not add up to 17% back. Each layer compounds on the price, so the real combined rate is lower — and each layer pays on its own schedule. Stack your actual layers below and see the honest number.
Cashback stacker: card + portal + rebate
Cashback layers multiply, they don't add — 2% + 5% + 10% is about 16.4% back, not 17%. Enter your layers and see the real combined rate.
Combined cashback $32.42 (16.2% real rate)
Naive addition would promise $34.00 — stacks compound: each layer earns on the post-discount amount, not the sticker price.
Estimate only. Shopping portals often post quarterly, rebates need claims, and card categories change — actual rates and timing come from each program's own terms.
Why the layers don't add
Percentage rewards multiply the same way stacked discounts do: a $200 purchase through a 5% portal earns $10, and a 2% card earns on the full $200 too — but the combined rate is 1 − (0.95 × 0.98) ≈ 6.9%, not 7%. Add a 10% rebate and the real figure is about 16.4%, not 17%. The gap is small per layer but grows with each one you stack.
Timing is the other half of the story: card cashback posts monthly or at statement close, shopping portals often pay quarterly and require the purchase to originate from their link, and rebates need a claim. Cashback stacks are a discount you wait for — the stacked discount calculator and the stacking simulator cover what comes off at checkout instead.
Whether a retailer even allows coupon layers on top of portal-tracked orders is a terms question — the documented per-retailer rules live in our coupon stacking guide and the retailer rules library.
Sources & verification
- DiscountCalc — coupon stacking rules by layer and retailer
- DiscountCalc — discount stacking simulator (order-sensitive)
- DiscountCalc retailer rules dataset — stacking and adjustment fields, 12 retailers (asOf 2026-10-16)
Sources last verified 2026-11-04. Retailer policies and sale calendars change without notice — treat the retailer's own help pages as the authoritative version before you buy.
Cashback rates, categories and payout schedules are set by each card issuer, portal and rebate program and change without notice. This calculator is a planning estimate — verify each layer's current terms before you buy.