Ecommerce · Amazon seller
FBA fees and returns had overtaken the margin on the hero ASINs.
This marketing & margin audit surfaced $61k in recurring annual margin in a DTC / Ecommerce business, evidenced, senior reviewed, and delivered in 6 days.
The business
This was an established third party seller doing strong volume on Amazon, with a handful of hero ASINs that drove most of the revenue and looked like dependable winners. The team watched top line sales and advertising ACoS closely, and by those measures the account was healthy, so the underlying per unit profitability of the bestsellers was rarely rebuilt from scratch.
What triggered the audit
Total profit stubbornly refused to grow in step with unit sales, a mismatch that points to per unit economics rather than demand. The audit rebuilt true contribution on the hero ASINs, loading in current FBA fulfillment and storage fees, referral fees and the real, rising return rate that the ACoS view completely ignored.
What the audit found
Rebuilt properly, the hero ASINs had slipped underwater without anyone noticing. Amazon’s FBA fulfillment and storage fees had crept up repeatedly, referral fees took their fixed share, and the return rate on the bestsellers had risen, and returned units carry their own inbound, inspection and frequent write off cost. Stacked together against prices that had held steady, these deductions had quietly overtaken the margin on the very ASINs the business leaned on most. Because the team steered by top line sales and advertising ACoS, none of it showed up: the ad metric looked efficient while the unit itself lost money after the marketplace took its cut and returns ate the rest. Across the hero range it came to roughly $61k a year of margin consumed by fees and returns.
What we changed
Rebuilt contribution per ASIN with current FBA, storage, referral and returns cost fully loaded, so profitability is judged after the marketplace takes its full cut rather than before it.
Repriced the affected hero ASINs and adjusted pack sizes to reduce dimensional fees and the return rate driving the leak.
Culled or reworked the SKUs that couldn’t reach a positive contribution once returns were counted, rather than subsidizing them on sheer volume.
Set a quarterly fee and returns review, so future Amazon fee increases trigger a pricing check before they erode margin again.
The result
The outcomes were measured for three months after a 90 day implementation period. The published chart shows net margin on hero ASINs moving from −2% to +6%, an 8 percentage point increase, after FBA fulfillment and storage fees, referral fees, and return handling and write off costs were included. Advertising ACoS was a steering metric, not the outcome measure. $61k a year recovered on the ASINs the business relied on most, an annual figure equal to 10× the $5,950 Audit + Sprint fee. For any marketplace seller, the trap is exact: advertising ACoS looked efficient while fees and returns quietly ate the unit beneath it. If you haven’t rebuilt contribution since Amazon last raised FBA fees, your bestsellers may be your biggest losers, and every sale deepens the hole. It takes loading fees and returns into per ASIN economics to see it. A fixed fee audit does that in days, before another quarter compounds the loss.
From kickoff to signed off findings: 6 days, inside our fixed 5–7 day window.
What the client said
$61k a year found in 6 days
Net margin on hero ASINs, fees & returns in: −2% → +6%
“ACoS looked efficient while our hero ASINs lost money. Victoria rebuilt contribution per ASIN with FBA fees, storage, referral fees and returns loaded in. We repriced and repacked the affected lines.”
Victoria MillerSenior Auditor · signed this audit off