Most of what we write about is judgement: where to aim spend, how to defend a price, when to launch. This piece is different. This is about money that is already yours, sitting inside your account, waiting for someone to do the arithmetic that retrieves it. Fee errors, mismeasurements and unreimbursed losses are a routine feature of operating at Amazon's scale, Amazon itself provides the mechanisms to correct them, and yet most brands have never once run the audit. At rankhouse it's standing work on every account, filed under a name that fits: fee forensics.
Why the errors exist at all
No malice required, just scale. Amazon measures millions of products with automated systems, warehouses billions of units, and processes over a million returns a day in the UK alone. At that volume, small error rates produce large absolute numbers: a product scanned with its packaging flexed lands in the wrong size tier; a returned unit goes astray between the doorstep and the shelf; a damaged item gets logged without the reimbursement that should follow. Each error is pennies or pounds. Multiplied by every unit, every month, since whenever it started, they become real money, and the burden of noticing sits entirely with you.
| What happened | Where it shows up | What to do |
|---|---|---|
| Inbound units lost or damaged | Shipment reconciliation discrepancies | Reconcile every shipment, claim the gap |
| Warehouse damage or loss | Inventory adjustments without reimbursement | Match adjustments to credits, claim the difference |
| Customer refunded, item never returned | Refund issued, no return scan within the window | Claim once the return window lapses |
| Wrong size tier or weight on file | Every single order overcharged | Remeasure, dispute, claim the historic overcharge |
| Fee category miscoded | Referral percentage higher than the category warrants | Audit category assignment ASIN by ASIN |
The audit, line by line
1. Dimensions and size tiers: the biggest single prize
Every FBA fee starts from your product's recorded dimensions and weight, and a millimetre or a few grams across a tier boundary changes the fee on every unit, forever. The method: pull Amazon's recorded dimensions for every ASIN, measure your actual packaged products, and flag every discrepancy, especially anything sitting suspiciously close to a tier line. Where Amazon's numbers are wrong, request a re-measure and pursue the correction. We've seen single re-measures worth four figures a year on one ASIN, and the 2026 structure raised the stakes: with fulfilment fees now carrying a percentage fuel surcharge, every wrongly-fat fee costs its error plus 1.5%, compounding the case we made in the fee changes scorecard for re-checking tiers this year specifically.
2. Lost and damaged inventory
Units vanish in fulfilment centres; units get damaged in handling; both are reimbursable under Amazon's own policies, and both frequently require you to notice first. The inventory adjustment reports carry the trail: reconcile what went in against what sold, what's held and what came back, and query the gaps within the eligible claim windows. This is patient, unglamorous reconciliation, which is exactly why it goes undone and exactly why it pays.
3. Returns that never came home
A refund to the customer should be followed by one of two things: the unit back in your sellable stock, or a reimbursement when it isn't. Track refunds against returned inventory over a rolling window and a persistent gap appears on most accounts, refunds issued, units never returned, reimbursement never triggered. Each instance is a claim; the pattern is a monthly report worth automating.
4. Fee-type spot checks
Beyond the big three: referral fees taken at the wrong category rate, storage billed on wrong volumetrics, charges that survived a programme change. A quarterly sweep of fee previews against actuals per ASIN catches drift early, and drift is the natural state of any billing system this complex.
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Get the free audit at rankhouse.co.uk →Doing it right: the house rules
- Document everything. Claims succeed on evidence: measurements, photos, report extracts, dates. Assemble first, claim second.
- Respect the windows. Claim eligibility periods are finite and have tightened over the years. A backlog audit captures what's still in window; the standing process ensures nothing ages out again.
- Stay inside the lines. File accurate, honest claims through the proper mechanisms. Spurious volume claiming is a policy risk, and unnecessary: the genuine errors are plentiful enough.
- Make it a system, not an event. The one-off audit recovers the past; the monthly cadence protects the future. On our accounts these checks run on schedule beside the kill list and the cover review, because leakage control is a rhythm, not a rescue.
Why this belongs in a growth strategy
Recovered fees arrive at 100% margin, no ad spend, no discounting, no new stock risk, which makes fee forensics the highest-margin activity in the entire account. And its second effect matters more than the cash: the audit forces true per-unit costs into the light, and true costs are the foundation every real decision stands on, as the Qualkem story showed from the first week. You cannot price, bid or forecast correctly on fees that are quietly wrong.
The free audit we run at rankhouse includes a fee forensics pass as standard: recorded versus actual dimensions on your catalogue, the reimbursement gaps in plain sight, and an honest estimate of what's recoverable. For some brands it's a modest housekeeping win. For a few, it has paid for the year's fees before we've discussed a single strategic idea. Either way, it's your money, and finding it shouldn't require anyone's permission.
Questions we get asked about this
How much money do brands typically recover from a fee audit?
Honestly: it ranges from housekeeping to remarkable, and anyone quoting you a universal percentage is selling. The drivers are catalogue shape and history: physically large catalogues near tier boundaries, high return-rate categories, and accounts that have never been audited recover most, because errors compound monthly from whenever they started. Single dimension corrections have been worth four figures a year on one ASIN; reimbursement reconciliations on busy accounts surface steady monthly recoveries; some tidy accounts yield modest sums and the more valuable by-product, verified true costs. The honest framing: it's your money, the audit is hours not months, and the downside case is confirmed-accurate economics, which is itself worth having.
Will filing lots of claims put my account at risk?
Filing accurate, evidenced claims through Amazon's own mechanisms is the system working as designed; the reimbursement policies exist precisely because errors are a known feature of operating at this scale. What creates risk is the opposite behaviour: spurious volume claiming, automated shotgun claims without evidence, or tools that file aggressively on your behalf hoping some stick, which is both a policy exposure and unnecessary, because the genuine errors are plentiful. The house rules that keep you safe: document first, claim second; respect the eligibility windows; claim what the evidence supports and nothing beyond it. Precision is both the compliant approach and, over time, the more profitable one.
What's the single most valuable check to run first?
Dimensions against size tiers, because it's the check where one finding repriced every future unit rather than just recovering the past. Pull Amazon's recorded dimensions and weight for every ASIN, measure your actual packaged products, and flag every discrepancy, prioritising anything sitting within a few millimetres or grams of a tier boundary, where mismeasurement is likeliest and costliest. Where Amazon's numbers are wrong, request re-measurement and pursue historical correction. The 2026 structure raised the stakes on exactly this check: with a percentage fuel surcharge now riding on fulfilment fees, every wrongly-fat fee costs its error plus 1.5%, forever, until someone does this hour of work.
Can't I just use one of the automated reimbursement services?
They have a place, and understand the trade before signing: typical services charge a substantial share of recoveries, often a quarter or more, and the aggressive ones create the claim-quality risks covered above. The maths that matters: the core checks, dimension reconciliation, refund-versus-return gaps, lost and damaged inventory, are systematic spreadsheet work that an operator who already lives in your data can run as monthly routine, keeping 100% of recoveries and, more importantly, feeding verified true costs into every pricing and bidding decision. Our view in practice: forensics belongs inside account management, not outsourced around it. If you do use a service, audit their claim quality and cap their scope.
How often should fee forensics run once the backlog is cleared?
Monthly for the reconciliations, quarterly for the sweeps, permanently, because leakage is a flow, not a stain: new mismeasurements happen, returns keep going astray, and fee structures now change every year, sometimes mid-year, creating fresh drift each time. The standing cadence we run: monthly, refund-versus-return gaps and inventory adjustments within claim windows; quarterly, fee-type spot checks of preview against actuals per ASIN and a dimensions review on anything new or repackaged; annually, a full pass timed to the fee-change announcements. Slotted beside the kill list and the cover review, it's an hour or two a month, and it's the highest-margin hour in the account, every recovered pound arriving at 100%.
Somewhere in your account is money that's simply yours: fees overcharged on mismeasured dimensions, stock lost or damaged without reimbursement, refunds issued for returns that never came home. No malice required, just Amazon's scale, where small error rates produce large absolute numbers and the burden of noticing sits entirely with you. The audit in order: dimensions against size tiers first, because one correction reprices every future unit and the fuel surcharge now multiplies every wrongly-fat fee; then lost and damaged inventory reconciliation; then refund-versus-return gaps; then quarterly fee-type spot checks. House rules: document first, respect claim windows, file only what evidence supports, and convert the one-off audit into a monthly cadence, because leakage is a flow, not a stain. Recovered fees arrive at 100% margin, making forensics the highest-margin hour in the account, and the by-product matters more than the cash: verified true costs, which every real decision stands on.
The next step is twenty minutes.
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About the author
Daniel Whalley is the founder of rankhouse, a boutique specialist agency for Amazon-focused growth in FMCG, health, wellness and beauty brands. He has spent 10 years inside Amazon accounts, generating £100M+ for the brands he works with, and manages £500k+ a month in ad spend across the UK, Europe and the US. He writes from inside the accounts he runs, not from the sidelines. Connect on LinkedIn → · amazon@rankhouse.co.uk