Every 7-figure FBA brand has them — SKUs that look fine in the aggregator dashboard but are net-negative once you bake in every variable cost. They survive for years because nobody runs the math at the unit level. The dashboard rolls them up into a green account-level number and the leak compounds quietly.
Here is the 30-minute audit we run on every new account.
What are the seven categories of margin-eating SKUs on Amazon?
- The fee-creep variant — same product, slightly heavier or larger packaging than the parent SKU. Fulfilment fee jumps a tier, margin disappears.
- The high-return variant — usually size/fit-driven. The product ships out and 12% comes back. You pay inbound + outbound + return processing every time.
- The aged-inventory ghost — sells slowly, sits in storage for a year, pays the long-term storage surcharge, and never recovers what it cost.
- The aggregator misprice — the price on Amazon is below your true cost-to-serve because the aggregator’s model used a stale fee table when it set the price.
- The free-shipping discount trap — the variant heavy enough to push the cart into a tier where marketplace shipping cost wipes the margin.
- The PPC-dependent SKU — turn off ads, sales drop 90%. You are not making money on the unit, you are renting attention from Amazon.
- The lost-sales variant — out of stock more than 8% of the time. The “good” SKU you are optimising for is actually one ranking position from disappearing.
How do I run the SKU audit inside Seller Central?
The aggregator dashboards do not run this math. Their “Profitability” view smooths storage fees monthly, ignores fee schedule lag, and uses 7-day attribution for ads. The settlement report is the only true source — see why aggregator software is lying to you.
What do I do with the SKUs that fail the audit?
You will typically find that 15–20% of SKUs produce 100% of your net profit — and the rest are eating it. The fix is not always to kill them. Sometimes it is repricing, sometimes it is repackaging, sometimes it is just letting the inventory burn down without reorder. But you have to see them first.
How often should I run this audit?
The brands that compound on Amazon are the brands that catch SKU drift inside a 30-day window. Everything else is just quarterly reporting on damage already done.
This SKU audit is the subsidy leak inside The Profit-Leak Method — the most counter-intuitive of the six leak categories and usually the second-biggest in dollars after ad waste.