The 856 ASN: the document where chargebacks are born
The Advance Ship Notice tells Walmart exactly what's on the truck, how it's packed, and which barcode is on every carton — before the truck arrives. It's also the document most likely to cost you money. Here's how it actually works.
The HL hierarchy: a tree flattened into segments
An 856 describes your shipment as nested levels, each an HL segment declaring its ID, its parent, and its type:
HL*1**S~ Shipment (carrier, tracking, ship date) HL*2*1*O~ Order (which PO — parent is shipment) HL*3*2*P~ Pack (a pallet or carton — parent is order) MAN*GM*00081234560000000116~ ← SSCC-18 barcode on that pack HL*4*3*I~ Item (UPC + quantity — parent is that pack)
Standard pack means every item sits inside an identified carton (S→O→P→I). Pick-and-pack shipments vary the structure. Walmart's guide defines which shapes it accepts per shipment type — using the wrong one is a rejection.
SSCC-18: the barcode that must match reality
Each pallet/carton gets an 18-digit serialized code: extension digit + your GS1 company prefix + serial + a mod-10 check digit. It appears twice — in the ASN'sMAN segment and printed as the GS1-128 label on the physical carton. If they don't match, the receiving scan fails — one of the top ASN chargeback causes. Verify any code with ourfree SSCC-18 check digit calculator.
The rules that actually get suppliers charged back
| Failure | Why it happens |
|---|---|
| Late ASN | The 856 must be transmitted before arrival — often before departure. Batch-sending "later" is how it's missed. |
| SSCC mismatch | Label printed from one system, ASN typed in another. |
| Quantity roll-up errors | Item quantities don't sum consistently up the carton→pallet→shipment tree. |
| PO mismatch | ASN references items or quantities that differ from the 850 (or the eventual 810). |
| Structure errors | Missing carton level, broken HL parent chain, wrong segment counts. |
Notice the pattern: every one of these is mechanical. Not judgment calls — checkable rules. Which is exactly why they shouldn't be handled by hand-keying fields into a browser form.
How suppliers create 856s today
Big suppliers: their EDI provider generates ASNs from their WMS automatically. Small suppliers: mostly hand-keyed into WebEDI from a warehouse spreadsheet — slow, and every keystroke is a chargeback opportunity. That gap is whatFluentEDI's 856 generator exists for: spreadsheet in, validated ASN out, every error explained before Walmart sees the file.