When rewards stack, and when they do not
A Rakuten click, a card-linked offer and your card's own earn rate all pay out on the same purchase. They stack — not as a loophole, but because three different parties are paying you for three different things.
The useful way to hold this is to ask who is sending the money. Once two rewards come from the same party for the same act, one of them is going to lose.
| Layer | Who pays | What it is for | What breaks it |
|---|---|---|---|
Your card's rate |
The issuer | Putting the purchase on their card | Nothing, short of a return. It is the only layer that always fires. |
A card-linked offer
American Express, Chase, Bank of America and Citi |
The merchant, through the issuer | Choosing that merchant | Not adding it before you pay; paying with a different card at the same bank; a minimum spend you missed; an expiry. |
A shopping portal
Rakuten, Chase Shopping and Capital One Shopping |
The merchant, through an affiliate network | Arriving at the merchant through their link | A second click from somewhere else; a coupon extension that re-clicks; gift cards; opening the checkout in a different browser. |
An airline shopping portal
AAdvantage eShopping, MileagePlus Shopping, SkyMiles Shopping, Mileage Plan Shopping and Rapid Rewards Shopping |
The merchant, through an affiliate network | The same click, paid in miles | Everything above, plus: the miles land in that airline's programme, so what the click is worth depends on what a mile there is worth to you. |
Why the three do stack
None of them can see the others. The portal is paid an affiliate commission by the merchant and hands you a share of it; it has no idea which card you eventually typed in. The issuer funds a card-linked offer out of a deal with that merchant and has no idea you arrived through a link. And the card's own rate is a term of the card, which does not change because of how you got to the checkout.
That is why the stack is worth more than the choice of card so often. Picking the right card out of a wallet moves the return by a rate difference; adding a portal click and an offer on top of it moves it by a multiple.
Why two portals do not
There is only one affiliate commission per sale, and it is attributed to the last link you clicked. So a second portal does not add to the first, it replaces it — and so does a coupon extension that quietly re-clicks an affiliate link on its way to finding you a code. The same rule explains most of the rest of the list: gift cards break attribution because the sale happens at the gift-card issuer, and a purchase started on a phone and finished on a laptop breaks it because the cookie is on the phone.
Card-linked offers have their own version of this. They attach to one card, not to an account, so an offer added on one card at a bank pays nothing when you swipe another card at the same bank. That is a quiet way to miss one, and it is the reason Cardful files every offer it reads against the account label the issuer's page named rather than against the bank.
What Cardful will add up, and what it refuses to
Your offers are worth a number only when the issuer itself stated one. A statement credit is a dollar amount, and a percentage back with a stated ceiling is a dollar amount. A bare percentage is not — without knowing what you are about to spend, it is a rate, and printing a currency symbol in front of a rate would be the most confident wrong number in the product. So those are counted, named on screen, and left out of the total rather than folded into it.
Points you hold and offers you have not used are shown as two lines and a sum, never as one figure. They are both money on these cards and they are not the same money: points are yours now, an offer pays only if you spend at that store before it expires.
Portal rates are the most perishable data in this product — they change daily, sometimes hourly. Cardful records eight portals (Rakuten, Chase Shopping, Capital One Shopping, AAdvantage eShopping, MileagePlus Shopping, SkyMiles Shopping, Mileage Plan Shopping and Rapid Rewards Shopping) and shows every rate with the date it was read, rather than claiming it is current. A stale rate you can go and check yourself still beats no information; a stale rate presented as current is how somebody comes to believe they earned ten times what they earned.
The airline portals are the ones worth the extra thought, because their payout is not dollars. five of the eight pay miles, in programmes this site already carries a published valuation for — so an airline portal's rate and a card's rate can be compared in the same unit, and a cash-back portal's cannot be compared to either without deciding what a point is worth to you first.
None of this involves connecting anything. Cardful holds no bank credential and speaks to no aggregator: an offers scan runs inside the tab you already opened, under the access clicking the toolbar icon grants, and it ends when that tab navigates away.
Every offer, next to the store it pays at.
Cardful reads the offers already on your cards and surfaces them at the checkout they apply to, so the stack is built before you pay rather than remembered afterwards.