Compliance Guide
FNSKU Labeling Rules for Amazon FBA: Full Compliance Checklist (2026)
By Alice Wu, CEO & Founder Published · Last updated
Short answer
Unless your products are enrolled in stickerless, commingled inventory, every individual unit, not just the master carton, needs its own FNSKU label with the manufacturer barcode covered or removed. Print at 300 DPI or better, place labels on a flat surface, and apply Transparency codes separately if enrolled.
What Is an FNSKU?
FNSKU (Fulfillment Network Stock Keeping Unit) is the barcode Amazon uses internally to identify a specific unit as belonging to your listing inside its fulfillment network. It is different from your product’s UPC/EAN and different from the ASIN shown on the listing page.
| Code | What it identifies | What to do with it on FBA units |
|---|---|---|
| FNSKU | A unit as belonging to your listing inside Amazon’s fulfillment network | Apply to every individual unit |
| UPC / EAN | The product, as printed by the manufacturer | Cover or remove so scanners can’t read it instead of the FNSKU |
| ASIN | Your listing on Amazon’s product page | No label needed; it’s a listing identifier |
| Transparency code | One specific unit, for brands enrolled in the Transparency Program | Apply separately, one unique code per unit, matched to the right SKU |
When You Need FNSKU Labels
- On every unit unless you use stickerless, commingled inventory — that is the only exception, and most private-label sellers are not enrolled in it.
- On every individual unit, not just the master carton — a common and costly mistake is labeling only the outer box.
Compliance Checklist
- Cover or remove existing manufacturer barcodes. If a scanner can read two barcodes on one unit, Amazon’s system may read the wrong one.
- Print at 300 DPI minimum so the barcode scans reliably on the first pass. If you’d rather not print in-house, see our label printing service.
- Place the label on a flat, visible surface — not over a seam, curve, or printed graphic that could obscure the scan.
- Match the label to the correct ASIN/condition — mixing new and used condition labels in one batch is a common rejection cause.
- Apply Transparency Program codes separately if your brand is enrolled — these are unique per-unit codes distinct from FNSKU, and a mismatch between the two can flag the entire shipment.
- Double-check expiration-sensitive categories (supplements, cosmetics) — these often require additional expiration date labeling alongside FNSKU.
The Most Common Rejection Causes We See
- FNSKU applied only to the carton, not individual units
- Old manufacturer barcode left visible next to the new FNSKU
- Transparency Program code applied to the wrong SKU within a mixed shipment
- Label printed too small or too low-resolution to scan reliably
Outsourcing Labeling vs. Doing It In-House
For sellers shipping from Chinese factories, applying labels at the factory (before goods are even boxed) is rarely practical — factories aren’t set up for Amazon-specific compliance checks. A dedicated prep step between the factory and the port catches errors before they become a rejected shipment three weeks later.
Our Amazon labeling service applies FNSKU, Transparency Program codes, and outer-carton shipping marks together, checked against your current shipment plan before anything is sealed.