Walmart Edi 855

What This Is

This guide covers the Walmart EDI 855 transaction: the Purchase Order Acknowledgment. The 855 is used by suppliers to confirm how a Purchase Order (PO) will be handled — whether items are accepted, rejected, or accepted with changes. Walmart uses the 855 to communicate acceptance and exceptions to POs that were sent via the EDI 850. Processing a correct 855 is critical for accurate fulfillment, inventory planning, and OTIF compliance.

The guide focuses on practical tasks you will perform day-to-day: parsing the 855, validating the key segments (ISA/GS/ST envelopes, the BIA/BIN/ACK loops), converting the 855 into CSV for ERP or warehouse systems, and troubleshooting the common errors Walmart trading partners encounter. It includes real EDI code examples, line-by-line explanations, and conversion rules you can implement in a script, ETL, or a data-mapping tool.

Who This Is For

This guide targets EDI analysts, integration engineers, warehouse operations teams, and vendor compliance specialists responsible for handling Walmart Purchase Order Acknowledgements and integrating them into downstream ERP/WMS systems.

Key Segments Explained

The 855 uses a number of X12 segments and loops. Below are the key segments you must validate and understand when working with Walmart 855 files.

• ISA / GS / ST (Envelope Headers) — The ISA (Interchange Control Header) and GS (Functional Group Header) contain envelope-level identifiers, delimiters, and control numbers. If ISA/GS control numbers do not match the functional ack (997) or downstream system expects different delimiters, the file will fail to parse.
• BIA (Beginning Segment for Purchase Order Acknowledgment) — The BIA provides the acknowledgment type code and reference PO number. Example: BIA*00*SA*123456789**20251125, where the second element is the acknowledgment type (e.g., SA = Acknowledgement). A missing or malformed BIA prevents you from mapping the 855 back to the originating PO.
• REF (Reference Identification) — REF segments carry secondary identifiers such as the vendor or buyer reference numbers. Walmart often passes a trading partner reference in REF*PD or REF*DP that you must map to internal IDs.
• N1 / N3 / N4 (Name and Address Loop) — Identifies parties (e.g., Walmart as the buyer and your company as the seller) and the shipping/ship-from locations. Incorrect or missing N1 loops will break partner matching and result in acceptance exceptions.
• PO1 (Baseline Item Data) — Each PO line acknowledged in the 855 uses PO1 to indicate the item number, quantity ordered, and unit of measure. PO1 lines are paired with an ACK or similar segment that communicates the acceptance status and quantity accepted.
• ACK (Line Item Acknowledgement) — The ACK segment (within the PO1 loop) carries the line-level acknowledgment code: IA (Item Accepted), RE (Item Rejected), PC (Price Changed), etc. You must parse ACK values into your system’s status codes to drive fulfillment decisions.
• CTT / SE / GE / IEA (Trailer Segments) — CTT gives line/item counts, SE marks the transaction set trailer with segment count, GE and IEA close the envelopes. Control numbers and counts must match their headers or automated validators will reject the file.

Example EDI Snippet

ISA*00*          *00*          *ZZ*SENDERID      *ZZ*WALMART       *231125*1700*U*00401*000000123*0*P*:~
GS*RA*SENDERID*WALMART*20231125*1700*123*X*004010~
ST*855*0001~
BIA*00*SA*PO1234567**20231125~
REF*IA*INVREF123~
N1*ST*WALMART STORES INC*92*0000123456~
PO1*1*100*EA*12.34*PE*BP*1234567890123~
ACK*IA*100*EA~
PO1*2*50*EA*5.00*PE*BP*2345678901234~
ACK*RE*0*EA~
CTT*2~
SE*12*0001~
GE*1*123~
IEA*1*000000123~

Line-by-line explanation:

• ISA*... — ISA envelope: sender/receiver IDs, date/time, control number 000000123. Validate element positions, especially the element separator and repetition separator declared in ISA.
• GS*RA* — Functional group header: transaction set type RA typically used for Purchase Order Acknowledgment group; group control 123.
• ST*855*0001 — Transaction set header for 855 with control number 0001. SE must reference the same control number and accurate segment count.
• BIA*00*SA*PO1234567**20231125 — Beginning segment: authorization/ack code SA and reference to original PO PO1234567, with date.
• REF*IA*INVREF123 — Reference identification for internal invoice or acknowledgment reference.
• N1*ST*WALMART STORES INC*92*0000123456 — Name loop indicating sold-to or ship-to party with an assigned identifier type 92.
• PO1*1*100*EA*12.34*PE*BP*1234567890123 — Line 1: quantity ordered 100, unit price 12.34, buyer part BP, GTIN.
• ACK*IA*100*EA — Line-level acknowledgement: item accepted IA for full quantity 100.
• PO1*2*50*EA*5.00*PE*BP*2345678901234 — Line 2: quantity ordered 50.
• ACK*RE*0*EA — Line-level ack: item rejected RE, quantity accepted 0.
• CTT*2 — Transaction totals: 2 line items acknowledged.
• SE*12*0001 — Transaction trailer: total segments count and control number must match ST.
• GE / IEA — Group and interchange trailers close envelopes and must match header control numbers.

CSV Output Example

Below is a simple CSV conversion mapping from the 855 snippet to a CSV table suitable for import into ERP or WMS systems. Each PO1 + ACK pair becomes a row.

Step-by-Step Conversion Process

1. Receive and verify envelope headers
   1. Check ISA envelope for correct delimiters (element separator, component separator, segment terminator). If your parser expects different characters, set them explicitly.
   2. Validate control numbers in ISA/GS/ST against expected trading partner control ranges. Record the interchange control for audit and 997 matching.
2. Validate BIA and PO mapping
   1. Extract the PO number from BIA and cross-reference to your internal PO records or the original 850. If the PO number does not exist in your system, flag for manual reconciliation.
   2. Confirm the BIA acknowledgment type (e.g., SA). Map standard acknowledgement codes to your internal status codes.
3. Parse PO1 / ACK loop into rows
   1. For each PO1 segment, read item identifiers (GTIN/UPC/BuyerPart), ordered quantity, UOM, and unit price.
   2. Immediately read the following ACK segment (if present) to determine Ack_Code and accepted quantity. If ACK is absent, apply rules: either default to IA or mark as unacknowledged depending on SLA.
4. Normalize dates and numeric formats
   1. Convert EDI dates (YYYYMMDD) to ISO (YYYY-MM-DD) for CSV compatibility. Normalize decimal separators (use period).
   2. Ensure quantity and price fields are numeric and within acceptable ranges; reject or flag negative or zero unit price values.
5. Generate CSV rows and validation report
   1. Write each mapped PO1+ACK pair to the CSV with header fields as shown above.
   2. Produce a validation report listing discrepancies (missing PO, rejected items, price changes) and save it alongside the CSV for operations review.
6. Send functional acknowledgment (997) and reconcile
   1. If the 855 passed syntactic validation, send a 997 functional acknowledgment back to Walmart or your VAN. Include correct control numbers from ISA/GS/ST.
   2. Monitor for 997 rejections and resolve any syntax/segment-count issues.
7. Automate with PlainEDI validation
   1. Before final processing, run the 855 through PlainEDI to catch delimiter mismatches, missing required segments, and wrong data types.
   2. Use PlainEDI pre-validation to prevent common rejections and to automatically generate a clean CSV for import into your ERP.

Common Errors and Fixes

• Error: ISA control number mismatch (ISA13 / IEA02) — Symptom: IEA shows a different control number than ISA/GS. Fix: Confirm control numbers are not overwritten by middleware. Ensure your EDI translator preserves ISA control numbers and increments them per interchange. Use PlainEDI to validate ISA/IEA consistency before acknowledging.
• Error: Segment terminator or delimiter mismatch — Symptom: Parser throws "Unexpected segment" or concatenates segments. Fix: Detect delimiters defined in byte positions of ISA (element separator in ISA) and configure parser accordingly. Use PlainEDI validation which auto-detects delimiters on upload.
• Error: Missing BIA or PO number — Symptom: Unable to map acknowledgment to the original PO. Fix: Reject or route to manual review. Check whether BIA is present and the BIA03 contains the PO. Update trading partner mapping if Walmart sends PO number in REF instead.
• Error: ACK code not recognized (invalid acknowledgment status) — Symptom: System cannot map ACK values. Fix: Validate against allowed codes (IA, RE, PC, QU) and add a mapping fallback to log unknown codes for operations review.
• Error: SE segment counts do not match actual segments — Symptom: 997 shows rejection with segment count error. Fix: Recalculate SE segment count (count includes ST and SE) and ensure your EDI generator writes the correct count. Many translators allow auto-counting; prefer automatic generation of SE values.
• Error: Wrong N1 identifiers or missing partner ID — Symptom: Your system cannot associate the 855 to the correct ship-to. Fix: Update partner table to include the N1*92/03 values Walmart uses or map alternative REF identifiers. Use a mapping table with multiple identifier types.
• Error: Quantity accepted exceeds ordered quantity — Symptom: ACK shows accepted qty greater than PO1 ordered qty. Fix: Flag as business error and reject the 855 to manual review. Validate business rules: accepted_qty <= ordered_qty unless explicit backorder rules apply.

Related Resources

Further reading and adjacent topics that will help you handle Walmart EDI integrations:

• reading 997 functional acknowledgments
• walmart suppliers edi to csv conversion
• how to read walmart edi 850
• common errors walmart edi files
• understanding edi x12 delimiters and structure
• edi to csv for small business vendors

FAQ Section

Q: What is the purpose of the EDI 855 for Walmart?

The EDI 855 Purchase Order Acknowledgment confirms how you will handle line items on a Walmart PO. It communicates acceptance, rejections, quantity changes, or price changes back to Walmart and serves as the canonical acknowledgment that drives shipping and fulfillment processes.

Q: How do I map ACK codes from the 855 into my ERP?

Map ACK codes such as IA (Item Accepted), RE (Item Rejected), and PC (Price Changed) to your ERP status fields. Implement a mapping table and include a fallback to flag unknown codes for manual review. Validate that accepted quantities do not exceed ordered quantities before writing to the ERP.

Q: What causes SE segment count mismatches and how do I fix them?

SE count mismatches occur when the segment count written in SE does not equal the actual number of segments between ST and SE. Fix this by using your translator's auto-count feature or implement a segment counter in your EDI generator to compute and inject the correct value.

Q: My parser fails due to delimiter issues. What should I check?

Check the ISA segment for the declared element separator, component element separator, and segment terminator characters. Configure your parser to use those characters. Many failures happen because middleware changes delimiters; use PlainEDI to auto-detect and validate delimiters on file upload.

Q: Should I always accept PO items that don’t have an ACK segment?

No. If a PO1 is not followed by an ACK, treat it as an unacknowledged line. Define a business rule: auto-accept only when a formal SLA allows it; otherwise route to an exception queue. Record the exception and notify planning/ops teams for manual confirmation.

Q: How do I handle price changes communicated in 855?

If ACK or other segments indicate a price change (PC), capture the new price and apply it per contract rules. Flag price changes for finance/ERP reconciliation. Do not write price changes to payable accounts without approval workflows.

Q: What penalties are associated with poor 855 processing for Walmart?

Walmart enforces OTIF and other compliance penalties for mismatches and late responses. Check your Walmart Retail Link portal for current penalty details and thresholds. Common penalty types include OTIF non-compliance penalties and chargebacks for ASN inaccuracies and late fulfillment.

Q: Can PlainEDI prevent common 855 errors?

PlainEDI provides pre-validation that checks envelope consistency, delimiters, required segments, data types, and segment counts. Using PlainEDI reduces 997 rejections and prevents many operational errors by flagging structural or data issues before import.

Practical Case Studies and Real-World Scenarios

Scenario 1 — Missing ACK segments: A supplier's nightly ingestion process treated every PO1 without a following ACK as accepted. This caused inventory reservations for items Walmart had cancelled. Fix: Implement the rule to mark missing ACKs as exceptions, run a reconciliation report, and use PlainEDI validation to flag missing required loops.

Scenario 2 — Delimiter corruption due to FTP transfer: An automated SFTP process inserted Windows CRLF characters into a segment terminator position. The parser concatenated two transaction sets and failed syntactic validation. Fix: Add a pre-processor that normalizes line endings and validate delimiters using PlainEDI before mapping to CSV.

Scenario 3 — PO number in REF instead of BIA: A vendor exchange changed format and began sending the PO number in REF*PO rather than BIA03. The automated mapping failed to join to PO headers. Fix: Update mapping rules to check both BIA03 and REF*PO for PO references and add a fallback lookup for alternate identifiers.

Best Practices

• Automate segmentation and delimiter detection to avoid parsing errors.
• Always validate ISA/GS/ST control numbers and SE segment counts programmatically.
• Map all possible locations for the PO number (BIA03 and REF loops) to avoid missed matches.
• Implement a business-rule engine to handle ACK code actions (accept, reject, price change).
• Keep an audit trail of original EDI files, parsed CSVs, and validation reports for compliance and dispute resolution.

When you need a quick, reliable validator or a conversion path for Walmart EDI 855 files, upload your file to PlainEDI to catch delimiter, envelope, and segment issues before your ERP or WMS processes them. PlainEDI's validation reduces rework and helps you stay compliant with Walmart's trading partner requirements.

For deeper guidance on related EDI transactions and troubleshooting, review these topics: edi to csv for small business vendors, reading 997 functional acknowledgments, and understanding edi x12 delimiters and structure.