FBA Prep Requirements 2026: The Checklist That Prevents Inbound Rejects

Amazon rejects thousands of shipments every year — not because the products are bad, but because the prep is wrong. A missing FNSKU label or an unsealed poly bag sends your inventory straight back.

And in 2026, the stakes got higher. As of January 1, 2026, Amazon no longer performs prep or labeling corrections for sellers. Every unit must arrive fully labeled and packaged, or you pay the penalty (PrepVia, 2026).

Key Takeaways

• Amazon killed its own prep service on January 1, 2026 — every unit must arrive fully prepped
• Inbound defect fees reach $0.32–$5.72 per unit for standard items, $0.85–$8.25 for oversize
• After March 31, 2026, FNSKU labels are mandatory — manufacturer barcodes are no longer allowed
• Prohibited void fill (packing peanuts, shredded paper) is a guaranteed reject

The 2026 Change That Rewrote the Rules

The single biggest shift is prep responsibility. Amazon used to fix your labeling mistakes for a fee. That service is gone.

The penalty math is punishing. Inbound defect fees run $0.32–$5.72 per unit for standard items and $0.85–$8.25 for oversize (Snapl, 2026). A 500-unit shipment with a labeling defect now costs hundreds in penalties — plus the rejection delay.

There's also a hard deadline: after March 31, 2026, resellers must use FNSKU labels exclusively. Manufacturer barcodes are no longer allowed (Snapl, 2026).

FNSKU Labeling Checklist

Labeling is where most rejects happen. Here's the complete list:

• One scannable barcode per sellable unit — preferably the FNSKU
• Cover all manufacturer barcodes (UPC, EAN, ISBN) so only one barcode is visible
• Place on a flat surface — not over seams, folds, corners, or glossy stock
• Print at 100% scale, 300+ DPI with thermal or laser printing
• Test-scan before sealing and before shipment

Common label sizes are 1" × 2⅝" (30-up) or 2" × 1". The barcode must remain scannable through the outer packaging without opening it.

For bundles, use one FNSKU for the entire set and mark "Sold as set — do not separate."

Poly Bag Checklist

Poly bags are required for apparel, soft goods, and loose parts. The spec is precise:

• Minimum thickness: 1.5 mil (2 mil is common)
• Transparent and sealed with adhesive strips, heat seal, or tape
• Bags with a 5-inch or larger opening need a suffocation warning
• The FNSKU must stay scannable without opening the bag

A folded-over, open-mouthed bag is a reject waiting to happen. Seal it properly.

Carton and Box Checklist

Carton limits are absolute — exceed them and the carton is rejected:

• Maximum weight: 50 lb (22.7 kg)
• Maximum dimension: 25 inches on any side
• Cartons 33–50 lb need "Team Lift" labels on all five sides
• Use new or like-new corrugated boxes
• Remove all old shipping labels and barcodes
• Each carton needs a unique FBA Box ID label matching declared contents

The void-fill rule catches people off guard: packing peanuts and shredded paper are prohibited. Use bubble wrap, air pillows, or polyethylene foam instead.

The Most Common Rejection Reasons

Knowing what gets rejected is half the battle. The recurring offenders:

• Missing or unscannable FNSKU labels
• Visible manufacturer barcodes alongside FNSKU
• Missing suffocation warnings on poly bags
• Cartons exceeding 50 lb or 25-inch limits
• Old shipping labels not removed
• Prohibited void fill (packing peanuts)
• Wrong item count vs. declared contents

Every one of these is preventable. That's the point — a proper FBA prep process in China eliminates them at the source.

The Pre-Ship Quick Reference

Before your shipment leaves, run this final scan:

• [ ] One scannable barcode per unit; manufacturer barcodes covered
• [ ] FNSKU on flat surface, scannable through packaging, 300+ DPI
• [ ] Poly bags 1.5 mil minimum, sealed, suffocation warning visible
• [ ] Team Lift labels on 33+ lb cartons
• [ ] No carton exceeds 50 lb or 25 inches
• [ ] Approved dunnage only
• [ ] "Sold as Set" stickers on bundles
• [ ] Carton labels match physical contents

Conclusion

FBA prep in 2026 is unforgiving, but it's also predictable. Every reject reason on the list is a documented requirement you can check before shipping.

Label correctly. Seal your poly bags. Respect the carton limits. And if you're sourcing from China, do the prep at the source — where it's cheapest and easiest to verify.

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