You shipped 240 units to an Amazon fulfillment center. Seller Central says 232 were received. Where did the other eight go? If you sell through FBA, that question is not hypothetical. It is a recurring line item in your business, and since October 2024 you have only 60 days per shipment to do anything about it.
Most sellers treat the Amazon warehouse as a black box: boxes go in, orders come out, and the numbers in between are taken on faith. That faith is expensive. Understanding what physically happens to a unit inside a fulfillment center (how it is checked in, stowed, transferred, returned, and sometimes lost) is the foundation for catching discrepancies while you can still claim them. This guide walks through the whole journey from a seller's perspective.
What an Amazon Fulfillment Center Actually Is
An Amazon fulfillment center (FC) is a warehouse built around speed of outbound shipping, not around keeping your inventory neatly in one place. Unlike a traditional 3PL warehouse where your pallets sit in dedicated bays, an FC uses random stow: your units are scattered across thousands of bin locations, often mixed on the same shelf with other sellers' products, because that placement makes picking faster.
Random stow sounds chaotic, but it works because every unit is barcode-tracked at every touch. A picker doesn't need your products grouped together; the system routes them to whichever bin holds the nearest unit. The trade-off is that your inventory has no physical home, only a database record, and when the database and the shelf disagree, the discrepancy shows up in your account as missing or found inventory.
Amazon operates many types of buildings (sortation centers, delivery stations, receive centers, and cross-dock facilities), but for an FBA seller, the fulfillment center is where the events that hit your account actually happen: receiving, stowing, picking, packing, and processing customer returns. Every one of those events generates a record in your Seller Central reports, and every handoff between them is a point where a unit can be miscounted, damaged, or lost.
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The Inbound Journey: From Your Carrier to a Bin
When your shipment arrives at the FBA warehouse, it does not get counted the moment the truck doors open. Inbound processing happens in stages, and your shipment's status in Seller Central reflects where it is in that pipeline, which is why received quantities often trickle in over days or even weeks.
Here is the typical path a unit takes from your supplier's box to a sellable bin location.
- 1
1. Dock check-in
The carrier delivers; Amazon scans box labels and marks the shipment delivered. No unit counts yet, just an acknowledgment that boxes arrived.
- 2
2. Receive
Workers or automated systems open boxes and scan individual units against your shipment plan. This is where 'units received' starts incrementing, and where miscounts are born.
- 3
3. Stow
Each unit is placed into a bin location (often a robotic pod) and the bin scan ties the unit to a spot. A unit scanned at receive but never stowed can vanish here.
- 4
4. Pick and pack
A customer orders; the unit is picked from its bin, packed, and shipped. Pick errors can send the wrong seller's unit out the door.
- 5
5. Return or removal
If the customer returns it, the unit is graded sellable, damaged, or unfulfillable, and either goes back to a bin or sits awaiting your removal order.
How Inventory Moves Between Fulfillment Centers
Your inventory rarely stays in the amazon warehouse you shipped it to. Amazon constantly rebalances stock across its network through inter-facility transfers, moving units closer to predicted demand. You will see this in inventory reports as units in 'reserved' status with a transfer designation; they exist, but they are on a truck or being processed at a new building.
Transfers matter to sellers for two reasons. First, every transfer is another physical handling event, and handling events are where units get damaged or lost. Second, transfers explain why your receiving numbers can look wrong when they are not: a shipment checked in at one FC may be partially forwarded to others before receive scans complete, so quantities appear, disappear, and reappear across locations. Patience is warranted for a week or two; blind patience past the claim window is not.
One Pool of Inventory, Several Sales Channels
Units sitting in an FC don't have to be sold on Amazon. Amazon Multi-Channel Fulfillment (MCF) lets you send a pick, pack, and ship instruction for an order that came from your own website, eBay, Walmart, or anywhere else, and the unit ships out of the same bin your Amazon orders draw from. Sellers running a Shopify store often price MCF against dedicated Shopify fulfillment services or a regular 3PL, and the trade-offs are real on both sides: MCF wins on not splitting your stock across two buildings, a 3PL usually wins on unbranded packaging, custom inserts, and cheaper long-tail storage. Fees for MCF vary by unit size, shipping speed, and whether the order came from an Amazon channel, so check the current MCF rate card rather than assuming FBA economics carry over.
For reconciliation, multi-channel fulfillment adds a wrinkle worth knowing about before it bites you. A unit that leaves the fulfillment center on an MCF order is a legitimate outbound event, so it will not show up as a loss, but it also will not appear in your Amazon sales reports. If you reconcile inventory against Amazon orders alone, MCF volume looks like shrinkage. Pull MCF fulfillments into the same ledger as your FBA orders, and the count reconciles.
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Why Receiving Discrepancies Happen
When shipped quantity and received quantity disagree, there are usually a handful of root causes. Some are Amazon's fault, some are yours, and some are the carrier's, and the fix is different for each.
Common causes worth checking before you file anything:
- •Counting errors at receive: a worker scans one unit and keys a case quantity wrong, or a case pack is logged as a single unit.
- •Mislabeled units: if your FNSKU label is wrong, missing, or covers the manufacturer barcode incorrectly, units get received against the wrong listing, or set aside as problem inventory.
- •Carrier shortage: a box never made it off the truck. Compare your bill of lading and box count against what Amazon checked in.
- •Prep issues: units quarantined for failed prep (bagging, bubble wrap, expiration dates) can sit outside received totals for a while.
- •Genuine loss inside the FC: a unit was scanned at the dock but never stowed. This is the category that reimbursement claims exist for.
- •Phantom discrepancies: receive scans still in progress or units mid-transfer. These self-correct; track them, but give them time before filing.
Returns, Damaged Units, and What Amazon Does With Them
Customer returns flow back into the fulfillment center and get graded. A unit judged sellable goes back into a bin and your available inventory. A unit graded 'customer damaged' or 'defective' becomes unfulfillable stock that sits until you create a removal or disposal order. A unit Amazon damaged in the warehouse, or lost after a return was accepted, is supposed to trigger a reimbursement.
The word 'supposed' is doing real work there. Two policy changes reshaped this: on November 1, 2024, Amazon began auto-reimbursing many lost-inventory cases in the US, which helped, but auto-reimbursement does not catch everything, and refunded-but-never-returned units remain a major leak. Then on March 31, 2025, Amazon switched reimbursement valuation to your manufacturing or sourcing cost (its own estimate unless you provide your actual costs), excluding your margin and fees. If you have not uploaded accurate unit costs, you are likely being reimbursed on Amazon's guess, which may be lower than reality.
Unfulfillable stock is not free to ignore, either. Anything sitting in a bin accrues monthly storage, and units that pass Amazon's day-in-inventory thresholds pick up an aged inventory surcharge on top (this is what most sellers still call amazon long term storage fees, renamed and restructured). Damaged returns you never dispose of are the classic case: they can't sell, they can't be reimbursed once graded customer-damaged, and they quietly bill you rent every month. Check the current storage and aged-inventory rates in Seller Central before deciding whether to remove, liquidate, or dispose, because the answer flips depending on unit size and how long the stock has been sitting.
Watch the refund-without-return case especially. Amazon sometimes refunds a customer who never sends the item back, or the return window lapses with no unit arriving at the FC. When that happens, you're owed either the unit or the money. Neither shows up on its own; you have to match refunds against physical return receipts to spot the gap, which is tedious by hand and exactly the kind of cross-check software does well.
Reconcile Shipped vs. Received, Every Shipment, Within 60 Days
On October 23, 2024, Amazon cut the claim window for fulfillment-center claims to 60 days, down from a previous window that was dramatically longer. That single change converted shipment reconciliation from a quarterly cleanup task into a standing deadline. If you discover in month four that an FBA warehouse shorted you 30 units in month one, that money is simply gone.
Here is an illustrative example of what is at stake. Say you ship 500 units of a product with a $14 sourcing cost, and 2% go missing at receive: 10 units. That is $140 of cost-basis reimbursement per shipment if you claim it, and $0 if you notice on day 61. A seller sending four such shipments a month is risking roughly $6,700 a year in unclaimed cost recovery alone, before counting lost margin on units that would have sold. (Your numbers will differ; the point is that small percentages compound across shipments.)
The reconciliation routine itself is simple: for each shipment, compare units shipped against units located (received plus in-transfer plus problem inventory) once receiving has settled, investigate gaps against the causes above, and file claims with supporting documentation (invoices, packing lists, proof of delivery) well inside the window. The hard part is doing it for every shipment, every time, with cost data attached.
One more accounting note: receiving discrepancies do not just cost reimbursements. They corrupt your inventory valuation. If your books say 500 units arrived but 490 actually did, your cost of goods sold and ending inventory are both wrong until someone reconciles. Tying shipment-level receiving data to perpetual inventory records is the unglamorous core of amazon fba bookkeeping, and it keeps the balance sheet honest, not just the reimbursement ledger. How these adjustments flow into your books and tax filings depends on your situation; consult your accountant or tax professional.
Tools for the Job: Software, Services, or Spreadsheets
You have three ways to run this discipline, and the honest answer is that each fits a different scale. At low volume (a few shipments a month, a handful of SKUs), a spreadsheet and a monthly calendar reminder genuinely suffice. Log each shipment, check it at the two-week and six-week marks, and file what's short. No tool required.
Past that, the math changes. An amazon reimbursement service typically audits your account for you and takes a percentage of whatever it recovers, often a substantial cut; you do nothing, but you permanently give up a slice of money that was already yours. Amazon reimbursement software flips the model: it flags discrepancies (receiving shortfalls, lost and damaged units, refund-without-return gaps) and you file or auto-submit claims, keeping what's recovered. When you compare options, check three things: whether it covers all discrepancy types or just FC losses, whether it attaches your actual sourcing costs to claims (that valuation change makes this the difference between full and partial recovery), and what it costs against what it finds. BeanHawk's FBA reimbursement audit is free with 100% of recoveries kept, which is worth using as a baseline before agreeing to pay anyone a percentage.
Whatever you pick, it should read your account directly. An Amazon Seller Central integration (SP-API access, granted once from your account's user permissions) is what lets a tool pull shipment plans, receipt events, and reimbursement records without you exporting reports by hand, and hand-exported reports are exactly where 60-day deadlines get missed. The same connection is what makes the bookkeeping side work: a QuickBooks Amazon FBA setup that only imports your settlement deposit tells you almost nothing, while one that also carries shipment-level receipts and unit costs lets you tie inventory on the balance sheet to units actually sitting in bins.
The same logic extends upstream. Amazon inventory management software that tracks units and costs per shipment gives your claims their evidence trail automatically, and most amazon seller tools that handle restock planning already hold half the data a reconciliation needs. However you assemble the stack, the test is simple: could you, in five minutes, say how many units of your top SKU Amazon should be holding and what each one cost you? If yes, your fba reimbursement service or software choice is a detail. If no, fix that first.
What This Means for How You Operate
Treat every inbound shipment to an Amazon fulfillment center as an open accounting item, not a fire-and-forget event. Practically, that means three habits: label flawlessly and photograph outbound pallets (your evidence for carrier and receive disputes), upload your true sourcing costs to Amazon so reimbursements are not based on estimates, and put a recurring reconciliation check on the calendar that closes each shipment well before day 60.
Remember the broader economics, too. Amazon's referral fees already take typically 8-15% of your sale price depending on category. Inventory that disappears inside the fulfillment network is margin leaking on top of fees you already pay. The fulfillment center is a remarkable machine, but it is a machine that handles your property at enormous scale, and at that scale, errors are not a possibility, they are a rate. Your job is to measure that rate and bill for it.