Most shoppers use one cashback source at a time — a card, or a browser extension, or a coupon code. “Stacking” means layering all three on the same purchase, so each one pays out independently.
The three layers
- Shopping portal: click through a cashback site before you shop, so the store’s affiliate commission gets routed to you.
- Cashback credit card: pay with a card that earns a flat or rotating percentage back, on top of the portal payout.
- Coupon or promo code: apply a discount code at checkout — this reduces what you pay, which is separate from what you earn back.
A worked example
Say a retailer is offering 5% through a shopping portal. You pay with a card earning 2% on all purchases. You also apply a 10% off coupon at checkout. On a $100 order: the coupon brings the price to $90, the card earns $1.80, and the portal pays 5% of the $90 sale — about $4.50. Total cashback: roughly $6.30, plus the $10 you saved upfront.
Common mistakes
- Opening the retailer’s app instead of clicking through the portal link — this usually voids the portal’s tracking.
- Using an ad blocker that strips the tracking parameters from the cashback link.
- Assuming every category qualifies — many cards exclude categories like gift cards or wire transfers from cashback.
Compare current portal rates on our full comparison page before you check out.