Walmart requires every supplier to be EDI-capable before shipping. The essentials:
- Four core documents: 850 (PO), 855 (PO Acknowledgment, due within 24 hours), 856 (ASN, sent before the shipment arrives) and 810 (Invoice)
- AS2 is the mandatory communication protocol, with digital certificates exchanged and tested before go-live
- GDSN participation is required for product data synchronization
- Certification testing runs through Retail Link, and chargebacks are automated — there's no grace period
Mid-onboarding and something's not passing? Ask us — Walmart certification is a road we've walked hundreds of times. Start a conversation.
You've been approved as a Walmart supplier — congratulations. Now comes the technical requirement that stops many vendors in their tracks: EDI compliance.
Walmart serves customers nearly 260 million times per week across more than 10,000 locations. To run at that scale, it requires all suppliers to exchange business documents electronically, using specific transaction sets, formats and timelines. There's no manual alternative: miss a deadline, send an incorrect document structure or fail certification testing, and your products don't ship — and chargebacks can run thousands of dollars per violation.
In this article
Why Walmart Requires EDI
Walmart mandates EDI because manual processes — emails, paper purchase orders, phone confirmations — can't operate at its scale and speed. EDI removes human data entry from the transaction flow, cuts errors and gives Walmart real-time visibility into what's coming, when and from whom.
For suppliers, compliance isn't just a Walmart checkbox. It's the foundation for avoiding chargebacks, building a reliable supply chain reputation and scaling into additional retail relationships. Suppliers who invest in proper setup from the start spend far less time firefighting than those who cut corners early.
Required EDI Transaction Sets
Walmart uses the ANSI X12 standard. Every supplier must send and receive four core documents:
| Transaction Set | Document | Timing Requirement | Notes |
|---|---|---|---|
| EDI 850 | Purchase Order | Sent by Walmart; receive and process promptly | Foundation of every Walmart transaction |
| EDI 855 | Purchase Order Acknowledgment | Within 24 hours of receiving the 850 | Failure to send triggers compliance flags immediately |
| EDI 856 | Advance Ship Notice (ASN) | Before the shipment arrives — typically within 30 minutes of ship | The most chargeback-prone document by a wide margin |
| EDI 810 | Invoice | After shipment, typically within 24 hours | Must reconcile with the 850 and 856 or payment stalls |
A word on the 856, since it's where new suppliers bleed money: the ASN must arrive before the truck, carry accurate carton contents and SSCC labels, and match the physical shipment exactly. Any discrepancy — a quantity, a missing carton, a wrong label — is an automatic chargeback, not a warning.
AS2: Walmart's Required Communication Protocol
Walmart requires all suppliers to transmit EDI documents via AS2 (Applicability Statement 2), which sends data over the internet inside a secure "envelope" using encryption and digital certificates — authenticated, receipt-confirmed delivery that meets Walmart's security standards. Practically, that means:
- An AS2 connection configured specifically for Walmart's systems
- Digital certificates exchanged and validated by both parties before going live
- The connection tested and certified before you can transact
- Certificate renewals and connection monitoring as ongoing responsibilities — an expired certificate takes your connection down mid-season
Managing AS2 in-house is technically demanding, which is why most suppliers have an EDI provider handle configuration, testing and maintenance. For the trade-offs, see our guide on choosing between AS2 and an EDI VAN.
GDSN: Product Data Synchronization
Beyond transaction-level EDI, Walmart requires suppliers to participate in a Global Data Synchronization Network (GDSN), which shares product data between trading partners automatically — update your product database, and Walmart's systems update in real time.
In practice, GDSN compliance means keeping item descriptions, dimensions, weights, GTINs and images accurate and current. Discrepancies between your GDSN data and Walmart's records create downstream problems in ordering, labeling and invoicing.
The Certification Testing Process
Before transacting live, you'll complete a formal certification process through Walmart's Retail Link supplier portal:
1. Accept the supplier agreement
After Walmart's merchandising team approves your products, the supplier agreement arrives through Retail Link. Read it carefully — it establishes your compliance obligations, chargeback structure and EDI requirements.
2. Obtain your Walmart supplier number
Walmart assigns a unique supplier number that identifies you across its systems. It's required for EDI configuration and must appear in your transaction sets.
3. Configure your AS2 connection
Work with your EDI provider to configure the connection to Walmart's specifications, exchange certificates and verify connectivity before testing begins.
4. Build document mappings
Each transaction set — 850, 855, 856, 810 — needs its own mapping between Walmart's formats and your internal systems. Mapping errors are the most common cause of testing failures, which is where an experienced provider earns its keep.
5. Complete certification testing
Walmart requires test transactions for every document type before go-live, validating format, required fields and timing. Failures must be corrected and retested before you can ship.
Stuck at one of these five steps, or staring at a test failure you can't decode? Ask us — we've walked hundreds of suppliers through Retail Link certification, and we're happy to tell you what Walmart's testing team is actually looking for. Tell us where you're stuck.
Common Rejection Errors and Chargebacks
New Walmart suppliers most often get hit in these six spots:
- ASN sent after the shipment arrives rather than before
- ASN contents that don't match the physical shipment — wrong quantities, missing cartons, incorrect SSCC labels
- Missing required fields in the 855 acknowledgment
- Invoice amounts that don't reconcile with the original purchase order
- Incorrect or missing GTINs on item data
- Certificate expiration knocking out the AS2 connection
Walmart operates a zero-tolerance compliance policy — unlike retailers that give new suppliers a grace period, its chargeback system is largely automated, and errors trigger deductions immediately. That's why getting the setup right before go-live matters more than fixing it after. For what chargebacks actually cost as they compound, see our guide on EDI compliance requirements for retailers.
One more scope note: if you're selling through Walmart's online marketplace as a Drop-Ship Vendor rather than shipping to distribution centers, the requirements differ significantly — see our guide to Walmart EDI for drop-ship vendors.
Facing your first Walmart purchase order, or already live and tired of deduction surprises? Talk to us. We handle AS2 setup, certificate management, document mapping and certification support as part of the standard plan — and honestly, walking suppliers through Walmart onboarding is one of our favorite conversations. No demo required.
Let's talk Walmart EDIFrequently Asked Questions
Does Walmart require EDI for all suppliers?
Yes. Walmart requires all suppliers to be EDI-capable — there is no manual alternative for ongoing business. Suppliers must use AS2 as the communication protocol and exchange documents in the ANSI X12 format.
What EDI transaction sets does Walmart require?
Walmart requires four core transaction sets: EDI 850 (Purchase Order), EDI 855 (Purchase Order Acknowledgment), EDI 856 (Advance Ship Notice) and EDI 810 (Invoice). The 856 ASN is the most chargeback-prone — it must be sent before the shipment arrives and match the physical shipment exactly.
What is AS2 and why does Walmart require it?
AS2 (Applicability Statement 2) is a secure protocol for transmitting EDI data over the internet using encryption and digital certificates. Walmart requires it because it provides authenticated, encrypted, receipt-confirmed delivery — the standard Walmart mandates for all supplier connections.
What is GDSN and why does Walmart require it?
GDSN (Global Data Synchronization Network) lets suppliers and retailers share product data automatically and in real time. Walmart requires it so that when a supplier updates its product database, Walmart's systems update simultaneously — eliminating the data discrepancies that cause order errors and chargebacks.
What happens if my EDI documents don't pass Walmart's testing?
Your products can't ship until the issues are resolved. Common failure points include incorrect document structure, missing required fields, ASN timing errors and mismatches between the 850, 856 and 810. An EDI provider experienced with Walmart's testing process significantly reduces the risk of failures.
Can BOLD VAN handle my Walmart EDI setup?
Yes. BOLD VAN configures and maintains your AS2 connection, handles all document mapping to Walmart's specifications, manages trading partner onboarding and supports you through certification testing — all included in the standard service plan at no extra charge.
