What are the most common Amazon FBA Inventory Adjustment Reason Codes?

Code M represents misplaced (lost) inventory in the fulfillment center, Code F is found inventory, Code E is damaged at the FC, Code D is destroyed inventory, and Code P represents unsellable disposition changes.

How long does Amazon have to reimburse lost FBA inventory?

Under Amazon policy, fulfillment centers have up to 30 days to locate misplaced inventory (Code M). If the unit is not found (Code F) or automatically reimbursed after 30 days, sellers are entitled to file a reimbursement claim.

What is the 45-day customer return rule in FBA?

When Amazon issues a refund to a customer, the buyer has 45 days to return the physical product to an FBA warehouse. If 45 days elapse without the unit returning to sellable inventory or being credited, Amazon owes the seller a full reimbursement.

Amazon FBA Reimbursement Guide: Reason Codes & Dispute Playbook

Across millions of shipments flowing through Amazon’s fulfillment centers each day, between 1% and 3% of all FBA inventory is misplaced, damaged by forklifts, or lost after customer refunds. While Amazon has automated reimbursement routines, internal audits confirm that up to 40% of eligible discrepancies are missed, silently eating into merchant profit margins.

💡 Key Takeaway:

Third-party agencies like GETIDA charge 25% of every dollar Amazon gives back to you. By understanding the three core Seller Central reports and Reason Codes, you can claim 100% of these reimbursements directly without recurring commission deductions.

1. Amazon Inventory Adjustment Reason Codes Decoded

When you download your Inventory Adjustments report from Seller Central (Reports > Fulfillment > Inventory Adjustments), Amazon encodes warehouse events using single-letter and numeric codes.

Code	Adjustment Type	Official Description	Reimbursable?
M	Negative (-)	Inventory misplaced (Lost in warehouse)	Yes (after 30 days)
F	Positive (+)	Inventory found (Previously lost unit located)	Offsets Code M
E	Negative (-)	Damaged at Amazon fulfillment center	100% Uncontested
D	Negative (-)	Destroyed or disposed by Amazon	100% Uncontested
P	Negative / Positive	Disposition change to Unsellable	Yes (FC Fault)
Q	Negative (-)	Damaged during handling / carrier transit	100% Uncontested
H	Negative (-)	Damaged by customer return	Subject to return policy

2. The 30-Day Lost Inventory Netting Rule (M vs F)

Amazon fulfillment centers frequently misplace inventory bins during picking or stowing operations. When this happens, an adjustment with Reason Code M is recorded. Amazon's policy grants their warehouse teams 30 calendar days to find the lost merchandise.

If the unit is located, an adjustment with Reason Code F is created. The audit calculation is:

Net Reimbursable Units = ∑(Lost Units [M]) - ∑(Found Units [F]) - ∑(Auto-Reimbursed Units)

If your net lost balance for any FNSKU is positive and the oldest un-reconciled event is older than 30 days, Amazon is in violation of its own FBA Lost and Damaged Inventory Reimbursement Policy and owes you financial compensation.

3. The 45-to-60 Day Customer Return Window

When a customer clicks "Return or Replace Item" on Amazon, Amazon immediately debits the seller’s balance for the full refund amount. However, the buyer must physically ship the product back to an FBA facility within 45 days.

Two frequent billing leaks occur here:

Unreturned Merchandise: The customer received the refund, kept the item, and never returned it. Amazon's automated system was supposed to recharge the customer after 45 days, but failed to do so.
Warehouse-Damaged Returns: The item was returned in perfect condition by the buyer, but damaged by the carrier or warehouse staff during unpacking (logged with detailed disposition WAREHOUSE_DAMAGED). Per policy, Amazon is 100% financially liable for transit and handling damage.

4. How to Export the 3 Core Reports from Seller Central

You do not need to grant third parties API access or OAuth permissions. You can download the necessary reports in 3 simple steps:

Inventory Adjustments: Go to Reports > Fulfillment > Inventory Adjustments. Select date range (last 90–180 days) and click Download (TSV/CSV).

Fee Preview: Go to Reports > Fulfillment > Fee Preview. Click Request .csv Download to get exact package dimensions, weight bands, and billed fulfillment fees.

Customer Returns: Go to Reports > Fulfillment > Customer Returns. Select the last 90 days and click Download.

5. Ready-to-Submit Seller Support Case Template

When submitting an FBA reimbursement claim in Seller Central (Help > Contact Us > Fulfillment by Amazon > Other FBA Issues), use formal, policy-backed language:

Case Title: Request for FBA Inventory Discrepancy Reconciliation (Ref #[AUDIT_ID]) Issue Category: Fulfillment by Amazon > Other FBA Issues > Lost/Damaged Inventory Dear Amazon Seller Support Team, During our monthly inventory reconciliation, our audit identified uncompensated inventory variances totaling $[TOTAL_AMOUNT] USD under the Amazon FBA Lost and Damaged Inventory Reimbursement Policy. Attached is an itemized reconciliation spreadsheet containing: 1. Transaction Item IDs & FNSKUs for unreconciled misplaced units (>30 days elapsed under Reason Code M). 2. Fulfillment center damaged items under Reason Codes E and D. 3. Order IDs for unreturned customer refunds older than 45 days. We respectfully request that you review the attached ledger and apply the corresponding credit to our account. Thank you, FBA Inventory Operations Team

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