Costco, Amazon, and Other Portal-Excluded Retailers: Building Your Stack Around the Exceptions
The two biggest retailers in America are largely off-limits to shopping portals. Here's what still stacks at each, and why the workarounds are different for each one.
Why These Two Retailers Are Different
Amazon's marketplace structure — where a huge share of listings are sold by third-party sellers rather than Amazon directly — makes standard affiliate-portal tracking unreliable, which is the main reason Rakuten and TopCashback either exclude Amazon entirely or cap participation to specific, narrow categories that change frequently. Costco has historically restricted third-party affiliate and cash-back tracking on its site as a matter of policy, largely because its membership-fee business model doesn't need the same acquisition-marketing incentives a typical retailer relies on. Neither exclusion is a technical accident — both are deliberate choices by the retailers.
| Retailer | Portal Cash Back? | What Still Stacks |
|---|---|---|
| Amazon | Rare, narrow, and frequently changes — check before assuming | Amazon Prime Visa's 5% back on Amazon.com; card category bonuses generally don't apply since Amazon usually codes as its own MCC |
| Costco (in-warehouse) | No — in-person purchases can't be portal-tracked at all | Costco Anywhere Visa's elevated gas/restaurant/travel rates; Costco's own 2% executive membership rebate |
| Costco.com | Occasionally available on select portals for specific categories | Same as in-warehouse, plus whatever narrow portal coverage exists that week |
The Amazon Workaround
Because general-purpose category bonuses and shopping portals are largely neutralized at Amazon, the practical stack collapses to a single decision: does the Amazon Prime Visa's flat 5% back on Amazon.com purchases (for Prime members) beat whatever your best alternative card would earn there, factoring in that alternative's realistic points value? For most households, 5% flat cash back is difficult for a general transferable-points card to beat unless that card's category happens to cover the specific item being purchased (electronics sometimes code separately, for instance) — the Prime Visa is close to a default-correct choice for Amazon-heavy spend specifically because the rest of the stack doesn't apply there.
The Costco Workaround
Costco's own Costco Anywhere Visa by Citi (available only to Costco members) is purpose-built around this gap — it earns an elevated rate on gas (including at non-Costco stations), restaurants, and travel, categories that otherwise wouldn't get any portal or card-category treatment inside a Costco warehouse. Combined with the 2% annual reward the Executive membership tier already pays on qualifying Costco purchases, a household spending heavily at Costco can realistically capture 4%+ combined between the card and the membership rebate — without any portal involved at all, since none applies.
The Instacart and Third-Party Delivery Bridge
Costco and, to a lesser extent, other portal-resistant retailers are sometimes reachable indirectly through delivery services like Instacart, which do participate in some portal and card-linked-offer programs even when the underlying retailer doesn't. This isn't free — delivery fees and markup on item prices generally offset some or all of the portal/offer value — but for a large enough order, or when a card-linked offer specifically targets Instacart with a flat statement credit, the math can still favor ordering through the delivery service over an in-person Costco run, particularly if a card's dining/delivery category bonus also applies to the Instacart charge itself.
Bottom Line: Let a Purpose-Built Co-Branded Card Do the Work at Amazon and Costco
Don't force the five-layer framework onto retailers it wasn't built for. Amazon and Costco both reward a different approach — a purpose-built co-branded card doing most of the work — rather than trying to recreate portal-and-coupon stacking that these two retailers have specifically engineered their systems to prevent.
Frequently Asked Questions
Why don't shopping portals work well at Amazon?
Amazon's marketplace structure, where many listings are sold by third-party sellers, makes standard affiliate-portal tracking unreliable — Rakuten and TopCashback either exclude Amazon entirely or cap participation to narrow, frequently-changing categories.
What's the best card to use at Amazon?
For most households, the Amazon Prime Visa's flat 5% back on Amazon.com purchases (for Prime members) is difficult for a general transferable-points card to beat, since portals and most category bonuses don't apply there.
Can I earn cash back on in-warehouse Costco purchases?
Not through a shopping portal — in-person purchases can't be portal-tracked. The Costco Anywhere Visa by Citi and the Executive membership's 2% annual rebate are the main levers, together capable of 4%+ combined on Costco-heavy spending.