For Amazon sellers looking to sell the same product through both Fulfilment by Amazon (FBA) and Fulfilment by Merchant (FBM), understanding how to manage SKUs is crucial. A common issue sellers encounter is the error message: "Merchant SKU already exists. Merchant SKUs cannot be reused."
This happens because Amazon requires each offer to have a unique SKU, meaning you cannot use the same SKU for both FBA and FBM. This can complicate inventory management, especially when trying to maintain a consistent SKU structure across all your sales channels.
The difference between FBA & FBM
- FBA (Fulfilment by Amazon): Amazon stores, picks, packs, and ships your inventory.
- FBM (Fulfilment by Merchant): You, the seller, are responsible for storing, packaging, and shipping orders directly to customers.
For Takealot sellers new to selling on Amazon:
FBA is similar to selling items “In Stock” on Takealot, while FBM is similar to selling via “Lead Time”
The SKU challenge for dual fulfilment
Amazon requires a unique SKU for each fulfilment method. If you're adding an offer for the same product (under the same ASIN) for both FBA and FBM, you cannot reuse the same SKU across both listings.
Some sellers try to manually delete and recreate listings to bypass this issue, but that’s an unreliable and time-consuming solution. Instead, a structured SKU naming convention ensures smooth inventory management and prevents errors.
The SKU workaround
- Assign your base SKU to either FBA or FBM (e.g.
SKU).
- Append a suffix to the other SKU variant to differentiate it (e.g.
SKU-FBAorSKU-FBM).
For example:
- If your base SKU is
SKU123456and you list it first as FBM, your FBA SKU would beSKU123456-FBA.
- Alternatively, if you list the base SKU as FBA first, your FBM SKU would be
SKU123456-FBM.
This method ensures that Amazon recognises each listing as unique while keeping the underlying product data consistent across systems.
Ok cool… but how do I sync both FBA and FBM orders to the same base SKU in my Inventory Management system or Accounting Platform? Not to mention I also sell on other marketplaces like Takealot, Makro and Bobshop.
Enters Wherehouse 🚀
How Wherehouse syncs your SKUs
Wherehouse seamlessly integrates with your inventory, order management, and accounting systems (like Cin7, Unleashed, Zoho, Xero, and more) to keep your stock and financials in sync.
- When syncing orders, Wherehouse recognises the base SKU.
- It ensures both SKU-FBA and SKU-FBM orders are linked to the same product in your inventory management system and/or accounting software.
- This keeps inventory levels accurate and prevents duplicate product records.
Why this matters?
✅ Prevents SKU Errors: Avoids the frustrating “Merchant SKU already exists” issue.
✅ Simplifies Inventory Tracking: Maintains a single source of truth across fulfilment methods.
✅ Ensures Seamless ERP Integration: Helps maintain consistent product data across platforms
By following this simple SKU structuring method, Amazon sellers can efficiently manage both FBA and FBM listings without encountering SKU-related issues.
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