Global commerce depends on barcodes and that includes Amazon’s FBA service too. Every unit that enters a fulfillment center is scanned, tracked, and shipped using label identifiers. The FNSKU vs UPC is an easy choice for many sellers. But in 2026, Amazon ended commingling and now applies different rules to different seller types regarding Amazon barcodes.
This guide explains how each identifier works, what changed this year, and when to use an FNSKU even if you depend on manufacturer barcodes.
How Product Identification Works on Amazon FBA
Amazon uses four identifiers to track each product:
- GTIN (Global Trade Item Number): Standardized product identifiers issued by GS1, the organization that manages barcode standards worldwide.
- The UPC (Universal Product Code) is the 12-digit GTIN format used in North America. UPC identifies a product globally, across every retailer that sells it.
- The EAN (Europe) and ISBN (books) are other GTIN formats.
- ASIN (Amazon Standard Identification Number): The identifier Amazon assigns to every product page in its catalog. There can be multiple listings for a single ASIN.
- SKU (Stock Keeping Unit): Also called merchant SKU or MSKU. It is your own internal code. You define it when creating a listing and can’t change it later. It is there so you can organize your listings in Seller Central.
- FNSKU (Fulfillment Network Stock Keeping Unit): The FNSKU is an Amazon-exclusive barcode that ties a specific unit in a fulfillment center to a specific seller account.
Every FBA SKU is assigned an FNSKU in Amazon’s system, but that does not mean every unit needs an FNSKU sticker. When a SKU is set to track by manufacturer barcode, Amazon scans the UPC already printed on the packaging and no additional label is applied.
There is a quick way to check which system any of your SKUs uses.
Open Manage All Inventory and look at the FNSKU column. If the code shown starts with B0, it is displaying the ASIN, which means the SKU tracks by manufacturer barcode (UPC). If it starts with X0, Amazon generated a true FNSKU for it and expects that barcode on every unit.
2026 Rule Changes To FBA Labels
Two policy changes took effect this year:
Commingling ended on March 31, 2026. Each seller is now accountable only for their own stock, even when tracking by manufacturer barcode.
- Resellers must apply Amazon barcode (FNSKU) stickers to every unit, even when the product already carries a valid UPC. They can’t use a UPC to identify their products. Inventory received without the FNSKU sticker is treated as defective.
- Brand owners with the Brand Representative selling role in Amazon Brand Registry can keep using manufacturer barcodes without applying FNSKUs. Their inventory is tracked virtually and stays separate from everyone else’s.
Main insight: The manufacturer barcode option is tied specifically to the Brand Representative role.
The FBA Label Service ended on January 1, 2026. Amazon previously offered to apply FNSKU labels for you at a per-unit fee. That service was discontinued in the US store, so the labeling work now falls entirely on sellers and their suppliers
How to Set Your Barcode Preference
The barcode type is controlled by one setting.
Go to the Fulfillment by Amazon Settings section and scroll down to FBA Product Barcode Preference:
Whatever you select there, manufacturer barcode or Amazon barcode, applies to every new offer you create from that point forward. There is no changing during listing creation.
Once a SKU exists with a barcode type assigned, that choice is permanent for that SKU. If you need one SKU on a different barcode type, change the account preference, create the offer, then switch the preference back.
Before completing any shipping plan, check the barcode column for each SKU in the Send to Amazon section. It shows whether the unit will be tracked by the manufacturer’s barcode or the Amazon barcode. In this case, it’s UPC:
Note: Amazon requires a GTIN code to create new listings. If your product genuinely has no barcode, apply for a GTIN exemption.
When and How to Use FNSKUs
There are scenarios where using FNSKUs can be pretty useful, even if you’re operating with manufacturer barcodes.
Splitting lots into separate FNSKUs only pays off if you want to control which lot sells first. For many sellers, this simply doesn’t matter much.
But if your products have different expiration dates, creating a separate listing with an FNSKU can really help you track and quickly sell the batch you want.
It is simple: Once you have the two listings, lower the price on the lot with the nearer expiration date, and let it win the Featured Offer (the Buy Box). Once that lot sells out, restore normal pricing on the listing with the longer-dated stock and continue selling.
At the same time, you have to make sure Amazon correctly tracks both batches. Since the FNSKU is used only inside Amazon’s network, the label around it is yours to design.
You can include the product name, the condition (new or used), and any legally required warnings, such as the suffocation warning for polybags, directly on the label instead of applying a second sticker.
Bundles benefit too. A “Sold as set” line printed on the outer package label tells fulfillment center staff not to separate the items. And having the expiration date fully displayed here is important too. Here’s an example of what you can do:
If you sell consumables through Subscribe and Save, note that subscriptions are attached to a specific FNSKU.
When you retire an old lot and move to a new SKU, you will have to manually transfer the subscriptions from the old FNSKU to the new one.
How to Print Your Labels in Seller Central
Printing FNSKU labels takes about a minute. In Manage All Inventory, find the product, open the three-dot menu on the right side of the listing row, and select Print item labels.
That opens the Print Labels for Individual Products page. Enter how many labels you need for each SKU, pick a printing format, and click Print Item Labels. Amazon generates a PDF sized to your selection.
If your supplier handles packaging, you can skip stickers entirely by sending them the label PDF and having the FNSKU printed on the packaging artwork.
You are fully responsible for labeling now. Amazon discontinued its optional prep and labeling service in the US on January 1, 2026. It was an expensive convenience while it lasted.
Conclusion
On Amazon FBA, you can set your barcode preference before listing and use an FNSKU for extra control when selling different batches. Along with the customization for FNSKUs, this becomes a pretty useful choice if you end up needing it.
Frequently Asked Questions about Amazon FBA Labels (FAQs)
What is the difference between an FNSKU and a UPC?
A UPC is a universal product identifier issued through GS1 and used by retailers worldwide. An FNSKU is an Amazon-specific barcode that identifies inventory belonging to a particular seller within Amazon’s fulfillment network.
Do I need both a UPC and an FNSKU?
You need a UPC (or GTIN exemption) to create the listing. Whether the FNSKU also goes on the physical unit depends on you: resellers must sticker every unit with an FNSKU, while brand owners with the Brand Representative role can ship with the UPC alone.
Can I use a UPC instead of an FNSKU for FBA?
Only in certain cases. In 2026, Amazon allows manufacturer barcode tracking only for brand owners who hold the Brand Representative selling role in Amazon Brand Registry. Other sellers must label units with an FNSKU.
How can I tell whether a SKU uses a UPC or an FNSKU?
In Seller Central, open Manage All Inventory and check the FNSKU column. If the code starts with B0, the SKU is using manufacturer barcode tracking. If it starts with X0, Amazon generated an FNSKU for that SKU.
Can I change a SKU from UPC tracking to FNSKU tracking?
No. Once a SKU is created with a barcode type assigned, that barcode preference cannot be changed for that SKU. To use a different barcode type, you must create a new SKU.
Does Amazon offer FNSKU labeling?
No. Amazon discontinued its FBA Label Service in the U.S. on January 1, 2026.
Do Subscribe & Save subscriptions transfer automatically to a new FNSKU?
No. Subscribe & Save subscriptions are tied to a specific FNSKU. If you move customers to a new SKU with a different FNSKU, the subscriptions must be transferred manually.
Unsure If Your FBA Labeling Strategy Is Costing You Sales?
Barcode settings, FNSKU requirements, and inventory tracking rules have changed significantly in 2026. A small mistake can lead to receiving delays, stranded inventory, compliance issues, or operational costs.
Our Amazon specialists can review your current setup, identify potential risks, and help you develop a labeling and inventory strategy to support long-term growth.
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