Walmart EDI Requirements: Everything Suppliers Need to Know

If you’re coming to Walmart from other retailers, the first thing that will catch you off guard isn’t the transaction sets or the labeling — it’s the connection itself. Walmart requires AS2 (Applicability Statement 2) for virtually all EDI transmissions, with no Value-Added Network (VAN) fallback for most transaction sets. That’s a meaningful distinction, and it changes what you need on your side of the fence.

Why AS2 Is Different

Most suppliers who’ve done EDI before are used to the VAN model: you send documents to an intermediary network — think of it as an EDI post office — and the VAN routes them to the retailer. One connection, thousands of trading partners, built-in queuing and retry. It’s simple to set up and forgiving if your system goes down briefly, because the VAN holds your messages and delivers them when you reconnect.

AS2 is none of that. It’s a direct, encrypted, certificate-based connection between your server and Walmart’s EDI endpoint. There’s no intermediary holding messages for you. Both sides must be online and listening at the time of transmission, and each connection is authenticated using X.509 digital certificates that have to be installed, managed, and renewed on schedule. If your server is down when Walmart sends a purchase order, that document doesn’t get queued at a VAN waiting for you — it fails, and you may not know it failed unless your system is configured to alert you.

What this means practically: you need either a properly configured AS2 server that’s always on, with someone responsible for certificate renewals and monitoring, or a managed EDI provider who maintains that connection on your behalf. Suppliers who try to run AS2 on an ad-hoc basis — spinning up a server when they remember, letting certificates lapse — are the ones who show up in RetailLink with transmission failures on their scorecard.

Required Transaction Sets and Walmart-Specific Timing

Walmart requires the standard retail EDI transaction sets, but the timing windows are where they diverge from most other retailers:

• EDI 850 — Purchase Order: Inbound from Walmart. Straightforward — you receive it and process it.
• EDI 855 — Purchase Order Acknowledgment: Required within 24 hours of receiving the 850. Walmart uses this to confirm you’ve seen the order and can fulfill it as written; silence after 24 hours is treated as non-compliance, not as "they’ll get to it."
• EDI 856 — Advance Ship Notice (ASN): Required within 30 minutes of carrier pickup. This is the tightest ASN window in retail, and it exists because Walmart’s distribution centers run cross-dock operations — freight is unloaded from your truck and immediately sorted onto outbound trucks heading to stores, often without going into storage. The DC’s sorting system needs the ASN data pre-loaded so it knows where each carton goes the moment it comes off the truck. If the ASN isn’t there when the freight arrives, the cross-dock flow breaks and someone has to handle that shipment manually.
• EDI 810 — Invoice: Must match the original PO and the ASN exactly. Discrepancies between what you invoice and what Walmart’s receiving system recorded trigger automated deductions.
• EDI 860 — Purchase Order Change: Inbound from Walmart when they need to modify a PO after it’s been sent — quantities, dates, or cancellations. You need to be set up to receive and respond to these, not just the original 850.
• EDI 997 — Functional Acknowledgment: A technical receipt confirming each document arrived. On AS2, this is your proof of delivery — if Walmart sends an 850 and your system doesn’t return a 997, they have no confirmation the document landed.

RetailLink and the Vendor Scorecard

All Walmart suppliers must register on RetailLink (retaillink.walmart.com), Walmart’s supplier portal. See our trading partners page for the full list of retailers we support. This is where purchase orders land, where you access compliance documentation, and — critically — where your vendor scorecard lives.

The scorecard isn’t buried metadata. It’s a visible, buyer-facing performance report that tracks specific metrics: ASN on-time percentage, ASN accuracy, PO acknowledgment rate, and invoice accuracy, broken down by category, buyer, and time period. Your buyer can see it. Their category manager can see it. And when your score drops below Walmart’s threshold, it doesn’t just generate a chargeback — it triggers a conversation. Walmart’s vendor management team will reach out to your buyer, who will then reach out to you, and you’ll be expected to explain what went wrong and what you’re doing to fix it. That conversation is the real consequence of a poor scorecard, because it puts your account relationship — not just a single invoice — under scrutiny.

GS1-128 Label Requirements

Walmart’s carton label requirements are among the most detailed of any retailer:

• SSCC-18 (Serial Shipping Container Code) barcode in Zone D — each carton must have a unique, scannable identifier
• Specific font sizes for human-readable text
• Ship-to store or DC routing information in Zone A
• Vendor and department information in Zone B

These specs exist to feed the same cross-dock receiving system that depends on your ASN — the barcode on each carton is what the DC scanner reads to match it to the pre-loaded ASN data and route it to the correct outbound lane.

Before You Start Testing

If you’re onboarding with Walmart, the sequence matters. Get your AS2 connection certified first — that’s the gate everything else passes through. Then handle transaction set testing (855, 856, 810), then label review. Trying to test transaction sets over a connection that isn’t stable will waste a certification cycle, and Walmart’s compliance team expects you to come to testing with a working connection already in place.