Walmart Edi 850 | PlainEDI

TL;DR: This guide explains how to create, validate, convert, and troubleshoot Walmart EDI 850 Purchase Orders. You'll get real EDI snippets, line-by-line explanations, CSV mapping examples, common rejection codes and fixes, and step-by-step conversion instructions to export PO data to accounting or warehouse systems. Use PlainEDI for fast validation and CSV conversion before sending or ingesting Walmart 850s.

What This Is

This is a practical, step-by-step technical guide for working with Walmart EDI 850 Purchase Orders (POs). It covers structure, the key segments Walmart expects, sample transaction sets, CSV conversion examples, validation rules, and common errors you will encounter when exchanging 850s with Walmart or Walmart-affiliated DCs. The focus is on X12 850 transaction set content, not AS2/ VAN transport—though validation at the file level is covered.

The guide is intended to be actionable: you’ll find real EDI code snippets, annotated explanations of each element and segment, and conversion steps you can follow to map EDI data into CSVs for ingestion by ERPs, WMS, or reporting tools. It also explains why errors occur—such as delimiter mismatches, vendor ID errors, or missing PO lines—and gives concrete fixes and prevention tips.

Who This Is For

This guide is for EDI analysts, integration engineers, vendor compliance teams, and developers responsible for receiving or sending Walmart 850 Purchase Orders. If you handle Walmart retail POs, dropship POs, or integrate Walmart 850s into accounting or warehouse systems, this guide is written for you.

Key Segments Explained

Below are the core segments you’ll see in a Walmart 850 and why they matter. Each segment is explained with common sub-element content and Walmart-specific expectations.

ISA — Interchange Control Header

The ISA segment defines the envelope-level envelope. It sets fixed-width fields and delimiters and includes sender/receiver IDs and control numbers. Walmart commonly expects a specific ISA receiver qualifier and ID depending on your trading partner agreement. A mismatch in ISA IDs causes interchange-level rejects.

GS — Functional Group Header

The GS groups related transaction sets (ST–SE). GS includes an application sender and receiver code and a functional group control number. GS/GE control numbers must match and be unique internally; mismatches yield group rejection.

ST/SE — Transaction Set Header/Trailer

ST starts the 850 transaction set. SE ends it and must contain the correct segment count. Many 850 rejections result from incorrect segment counting in SE (off-by-one errors) or missing ST/SE pairs.

BEG — Beginning Segment for Purchase Order

BEG*00*NE*4501234567**20251112 sets the PO type and PO number and date. Walmart requires a valid PO number format matching vendor Portal expectations. Missing or misformatted BEG leads to downstream processing failures.

REF — Reference Identification

REF*IA*0123456789 commonly carries the Walmart Vendor/Supplier ID or other reference qualifiers. Walmart uses certain REF qualifiers (like IA) to identify vendor account numbers; if your REF qualifier value does not match what's on file, EDI systems will flag the PO for manual review.

N1/N3/N4 — Name and Address Loops

These segments define ship-to and bill-to locations. Walmart requires specific N1 qualifiers—N1*ST is ship-to—and the N3 and N4 must present an address that matches Walmart DC’s expected receiving location. Incorrect or missing N4 postal codes often block automated PO routing.

PO1 — Baseline Item Data

PO1 lines carry item identifiers, quantities, and prices. Walmart expects particular product identifiers (UPC/GTIN or Walmart SKU) in the correct composite form and consistent UOMs. If the PO1’s ID qualifier is wrong (e.g., using SKU instead of GTIN), the DC may reject or delay the order.

Example EDI Snippet

Below is a sample, simplified Walmart 850 with annotations. This example shows envelope headers and two PO line items. Line-by-line annotations follow the snippet to explain each segment’s purpose.

ISA*00*          *00*          *ZZ*SENDERID      *ZZ*WALMART       *231112*1253*U*00401*000000905*0*P*:~
GS*PO*SENDERID*WALMART*20231112*1253*905*X*004010~
ST*850*0001~
BEG*00*NE*4501234567**20231112~
REF*IA*12345678~
N1*ST*WALMART DC 123*92*9876543210~
N3*1234 WAREHOUSE BLVD~
N4*BENTONVILLE*AR*72716~
PO1*1*100*EA*12.34*PE*VN*1234567890123*UP*000123456789~
PID*F****Widget A - Red 10oz~
PO1*2*50*EA*5.50*PE*VN*9876543210987*UP*000987654321~
PID*F****Widget B - Blue 5oz~
CTT*2~
SE*14*0001~
GE*1*905~
IEA*1*000000905~

Line-by-line explanation:

ISA: Interchange control. Note the sender/receiver ID fields and date/time. The last char before the tilde sets the component delimiter (:) in this example.
GS: Functional group header. The functional ID code is PO for Purchase Order transactions.
ST: Transaction set header, with control number 0001.
BEG: Beginning segment containing PO type (00 for original), transaction set purpose (NE New Order), PO number, and date.
REF*IA*: Reference with qualifier IA (usually vendor ID). Walmart often uses specific REF qualifiers to identify vendor identities.
N1-N3-N4: Ship-to name and address for Walmart DC. N1*ST identifies the ship-to location.
PO1: Line items. The sequence is line number, quantity ordered, unit of measure, unit price, and product ID qualifiers with their values—here using VN (vendor) and UP (UPC).
PID: Product description for human-readable references.
CTT: Transaction totals — number of line items.
SE: Transaction set trailer; segment count must equal the actual segments from ST through SE.
GE and IEA: Group and interchange trailers—control numbers must match their headers.

CSV Output Example

This table demonstrates one common way to convert the EDI 850 into a flat CSV for ERP or WMS import. Each PO line becomes a row; header-level data (PO number, ship-to) repeats per row.

po_number	po_date	vendor_id	ship_to_name	ship_to_city	line_number	quantity	uom	unit_price	product_id_qualifier	product_id	description
4501234567	2023-11-12	12345678	WALMART DC 123	BENTONVILLE	1	100	EA	12.34	UP	000123456789	Widget A - Red 10oz
4501234567	2023-11-12	12345678	WALMART DC 123	BENTONVILLE	2	50	EA	5.50	UP	000987654321	Widget B - Blue 5oz

Step-by-Step Conversion Process

Follow these steps to convert a Walmart EDI 850 into a clean CSV and validate the transaction before processing or sending acknowledgments. Each numbered step includes sub-steps and verification checks.

Receive and verify the envelope
1. Confirm the transport layer (AS2/VAN) delivered the file intact and that you have the correct file encoding (usually ASCII/UTF-8).
2. Parse the ISA and GS headers. Verify sender and receiver IDs match your trading partner agreement. If not, stop and log an ISA mismatch.
3. Use PlainEDI to run an interchange-level validation that checks delimiter characters and ISA fixed-field widths automatically.
Validate ST/SE and segment counts
1. Parse each ST…SE block. Count segments and verify the SE segment's count matches.
2. If count mismatches appear, re-parse with a tolerant parser to detect invisible characters or extra CR/LF that inflate counts. Fix by normalizing line endings and re-counting.
Extract header-level PO data
1. Extract BEG (PO number and date), REF vendor IDs, and N1/N3/N4 ship-to address.
2. Validate vendor ID against your vendor master. If the REF vendor ID is unrecognized, consult the onboarding record or update your vendor mapping.
Parse PO1 line items into rows
1. For each PO1, extract line number, quantity, UOM, price, and all product ID qualifiers. Map the preferred product identifier (e.g., UPC) into the product_id column.
2. Use product master mapping to translate vendor IDs to internal SKUs. If a PO1 item lacks a mapped SKU, tag it and place it into a manual review queue.
Build the CSV rows and validate values
1. Normalize dates to ISO format (YYYY-MM-DD) and numeric fields (quantities and prices) to two decimal places where applicable.
2. Run business rule checks: minimal order quantities, price tolerances, and UOM validity. Flag and report exceptions.
Produce and deliver the CSV, then send acknowledgments
1. Write the CSV to your SFTP/inbound folder or submit to a webhook for ERP ingestion.
2. Send a 997 Functional Acknowledgment or 855 Acceptance as required by your agreement. Use PlainEDI pre-validation to ensure your outgoing 997/855 conforms, reducing 997/AK2 rejects.
Monitor and reconcile
1. Confirm the WMS/ERP accepted the CSV without errors. Reconcile PO line counts and quantities received with the source EDI 850.
2. Log any mapping exceptions and adjust product master or vendor mappings to prevent repeat errors.

Common Errors and Fixes

These are frequent problems with Walmart 850s, the typical error indicators (including common EDI code references), root cause explanations, and concrete fixes.

Error: ISA/GS Sender or Receiver ID Mismatch — Symptom: Trading partner rejects interchange or sends a 997 with AK1/AK2 errors. Cause: Incorrect ISA06/07 or GS02/03 values. Fix: Update the ISA/GS values to match the Walmart trading partner agreement, then re-send. Use PlainEDI to pre-validate ISA/GS headers before transmission.
Error: SE Segment Count Incorrect (SE Count Error) — Symptom: 997 rejection citing ST-SE segment count mismatch. Cause: Off-by-one counting due to extra segment terminators or invisible characters. Fix: Normalize delimiters and line endings, re-count segments programmatically, and correct the SE element value to equal the count of segments from ST to SE inclusive.
Error: Missing or Invalid REF*IA (Vendor ID) — Symptom: PO fails automated processing or is placed on hold. Cause: Vendor REF qualifier missing or vendor ID does not match Walmart records. Fix: Confirm the REF qualifier and vendor ID format (numeric vs. alphanumeric) against Walmart onboarding. Correct the REF or update your vendor master.
Error: PO1 Product ID Qualifier Mismatch (UPC vs. GTIN vs. Vendor) — Symptom: Line items don’t map to inventory. Cause: PO1 uses a non-expected ID qualifier (e.g., VN instead of UP). Fix: Update parsing logic to accept multiple qualifiers and implement priority rules (use UP if present, else GTIN, else vendor SKU). Update product master mappings accordingly.
Error: Address or N4 Postal Code Does Not Match Expected DC — Symptom: Automated routing fails; manual override required. Cause: Ship-to N4 values don’t exactly match Walmart DC address on file. Fix: Normalize address formatting (abbreviations, punctuation), and ensure the correct Walmart DC code is used in the N1 loop. Contact Walmart for official DC address updates if necessary.
Error: Unbalanced GE/IEA Group Counts — Symptom: Interchange-level rejection or 997 with IK segments. Cause: GE/IEA control numbers or counts do not match headers. Fix: Recompute GE and IEA counts to match the number of GS/IEA groups and correct control numbers. Ensure persistent control number generation to avoid duplicates.

Related Resources

For deeper or related topics, review these guides which complement your Walmart 850 work:

FAQ Section

Q: What is a Walmart EDI 850?

An EDI 850 is the X12 Purchase Order transaction set. For Walmart, it represents the PO the retailer issues to suppliers. It includes header details (PO number/date), ship-to addresses, and one or more PO1 lines describing items, quantities, UOMs, and prices.

Q: How do I validate ISA, GS, and ST segments before processing?

Validate envelope headers by checking sender/receiver IDs against your trading partner agreement and confirming control number sequencing. Use automated tools like PlainEDI to detect delimiter and fixed-width field errors in ISA. Then validate ST/SE segment counts and GS/GE group integrity.

Q: Why did Walmart return a 997 or reject my 850?

Common reasons include ISA/GS ID mismatches, incorrect SE segment counts, missing required header segments (BEG/REF), or invalid product ID qualifiers in PO1. Review the 997/AK segments for AK2/AK3 details, then correct and resend. Pre-validate with PlainEDI to minimize rejects.

Q: How should I map PO1 product identifiers to my internal SKUs?

Establish priority mapping rules—prefer UPC/GTIN identifiers if provided, then vendor SKU qualifiers. Maintain a product master table mapping Walmart IDs to your internal SKU. If an incoming PO1 lacks a mapped SKU, route it to a manual queue and update mappings once resolved.

Q: What are typical Walmart compliance penalties I need to watch for?

Walmart enforces penalties such as OTIF (On-Time In-Full) compliance and chargebacks for ASN/PO mismatches. Exact penalties change and are listed in Walmart’s vendor resources. Check your Walmart Retail Link portal for current penalty rates and thresholds and implement automated validations to prevent compliance failures.

Q: What should I include in the CSV for ERP ingestion?

At minimum: PO number, PO date, vendor ID, ship-to name and address, line number, quantity, UOM, unit price, product ID qualifier and value, and product description. Normalize dates and numerics and include an audit column pointing back to the original EDI filename and segment position for troubleshooting.

Q: How do I handle partial shipments and backorders indicated on an 850?

850s may indicate requested partial shipment tolerances or multiple ship dates using additional segments (e.g., SCH schedule). Parse SCH if present to respect multi-ship dates. If the 850 lacks schedule details, coordinate with the buyer for confirmation and reflect backordered quantities in your fulfillment system.

Q: What are the best practices to prevent 850 processing errors?

Best practices include: pre-validating files with tools like PlainEDI, maintaining an up-to-date vendor and product master, using robust parsing that supports multiple product ID qualifiers, normalizing delimiters and line endings, and automating 997 and 855 acknowledgment flows to catch issues early.

Final Notes and CTA

Walmart 850 processing requires careful envelope and transaction validation, accurate product and vendor mapping, and rigorous error handling to avoid penalties and delays. Use automated validation tools to catch common issues before they cause production failures. To validate and convert Walmart 850 files into CSV or to test your EDI before sending to Walmart, upload your files to PlainEDI and run pre-send checks that catch ISA/GS/SE mismatches, missing REF qualifiers, and segment count problems.

If you’re ready to validate and convert a Walmart 850 now, go to PlainEDI to upload your file and start automatic validation and CSV conversion.