EDI 855 - Purchase Order Acknowledgement

What is an EDI 855?

The EDI 855 is a purchase order acknowledgment used by suppliers to confirm, reject, or modify an EDI 850 purchase order.

The EDI 855 Purchase Order Acknowledgment is a seller’s formal response to an EDI 850 Purchase Order. It confirms whether the order is accepted, rejected, or modified, ensuring both buyer and supplier are aligned on quantities, pricing, and delivery before fulfillment begins.

What is EDI 855 in simple terms?

The EDI 855 is a supplier’s confirmation of a purchase order, indicating whether the order is accepted, rejected, or modified before goods are shipped.

Transaction Identity Block

Attribute	Description
Transaction Name	Purchase Order Acknowledgment
X12 Transaction Set	855
Functional Group	PR
Industry Usage	Retail, Grocery, Manufacturing, Distribution, Foodservice, Automotive
Primary Purpose	Confirm, reject, or modify a Purchase Order (EDI 850)
Typical Sender	Seller / Supplier
Typical Receiver	Buyer / Retailer
Common Preceding Transactions	EDI 850 (Purchase Order)
Common Following Transactions	EDI 856 (ASN), EDI 810 (Invoice), EDI 860 (PO Change), EDI 820 (Remittance)
Standard Version	ANSI X12 4010

What does an EDI 855 do?

The EDI 855 confirms whether a purchase order is accepted, rejected, or modified, enabling suppliers to communicate fulfillment capability before shipment.

It validates a purchase order at the business level by confirming acceptance, rejection, or changes. It also provides line-level acknowledgment, communicates delivery commitments, and establishes a verifiable audit trail that supports accurate fulfillment and invoicing

The 855 validates and confirms order intent at the business level by:

Confirming order acceptance or rejection
Communicating changes to quantities, pricing, or delivery
Providing line-level response detail via ACK segments
Establishing a formal audit trail for procurement

Why do retailers require an EDI 855?

Retailers require the EDI 855 to ensure suppliers confirm order acceptance and delivery commitments before fulfillment. This reduces supply chain disruptions, improves inventory planning, and enforces vendor compliance requirements.

Who Uses the EDI 855?

Role	Usage
Retailers	Require supplier confirmation of orders
Suppliers	Communicate fulfillment capability
Distributors	Coordinate multi-location fulfillment
Manufacturers	Confirm production feasibility
Logistics Teams	Align shipping and routing expectations

Who sends an EDI 855?

Suppliers and sellers send the EDI 855 to buyers in response to an EDI 850 purchase order. The transaction communicates whether the order can be fulfilled as requested or requires changes.

When Is the EDI 855 Required?

The EDI 855 is not universally mandated but is frequently required by trading partner agreements, especially in retail ecosystems (e.g., Walmart, grocery networks).

How quickly should an EDI 855 be sent?

The EDI 855 should be sent within the timeframe defined by trading partner agreements, typically within 24 to 48 hours of receiving the EDI 850 purchase order, depending on compliance requirements.

Is the EDI 855 Mandated Under Regulation?

The EDI 855 is not regulated under X12 mandates, but becomes effectively mandatory through:

Retail compliance programs
Vendor onboarding requirements
Supply chain SLAs and contractual obligations

What is the difference between EDI 850 Purchase Order and 855?

The EDI 850 is a purchase order sent by the buyer to request goods or services. The EDI 855 is the supplier’s response confirming whether the order is accepted, rejected, or modified, completing the order validation step in the procurement process.

How Does the EDI 855 Work in the Business Workflow?

The EDI 855 works by allowing suppliers to confirm, reject, or modify an EDI 850 purchase order before fulfillment. It validates order details, communicates supplier commitments, and ensures both trading partners are aligned on quantities, pricing, and delivery timelines.

Upstream Transactions

Stage	Transaction	Role
1	EDI 850 Purchase Order	Buyer submits purchase order

Downstream Transactions

Stage	Transaction	Role
2	EDI 855 PO acknowledgement	Seller confirms or modifies order
3	EDI 860 PO change	Buyer submits PO change (if needed)
4	EDI 856 Advance Ship Notice	Shipment notification
5	EDI 810 Invoice	Invoice
6	EDI 820 Remittance Advise	Payment/remittance

End-to-End Workflow Example

Buyer sends EDI 850
Seller responds with EDI 855 (AC, AD, RJ, etc.)
Buyer reviews and may issue EDI 860
Seller ships goods (EDI 856)
Seller invoices (EDI 810)
Buyer pays (EDI 820)

Industry-Specific Workflow Variations

Industry	Variation
Grocery	Frequent partial acknowledgments
Automotive	JIT adjustments and scheduling
Foodservice	Multi-location delivery confirmations
Retail	Strict compliance-driven acknowledgment timing

Cross-Standard Canonical Mapping

Canonical Function	X12	EDIFACT	SAP IDoc
Purchase Order	850	ORDERS	ORDERS05
Acknowledgment	855	ORDRSP	ORDERS05 (response logic)
Shipment	856	DESADV	DESADV
Invoice	810	INVOIC	INVOIC02

Where does the EDI 855 fit in the Order Lifecycle?

The EDI 855 sits between the purchase order (850) and fulfillment (856), acting as the formal confirmation layer. It ensures that both trading partners agree on order details before shipment, reducing errors, preventing disputes, and enabling synchronized supply chain execution.

How does PartnerLinQ use the EDI 855?

PartnerLinQ leverages the EDI 855 to:

Normalize supplier responses across networks
Provide transaction-level visibility
Automate ERP/OMS updates
Enable exception management and audit tracking
Reduce delays, disputes, and compliance violations

Where Is the EDI 855 Used?

Retail & Grocery
Apparel & Footwear
Manufacturing & Distribution
Foodservice
Automotive supply chains

Are there Industry-Specific Responses to the EDI 855?

Yes—responses vary based on BAK02 and ACK01 codes, enabling:

Full acceptance
Partial acceptance
Line-level changes
Rejection with or without detail

What Is the Purpose, Key Features, and Business Use Cases of the EDI 855?

The EDI 855 enables suppliers to confirm, reject, or modify purchase orders before fulfillment. It ensures alignment between buyer and seller, improves order accuracy, supports compliance, and provides visibility into supplier commitments across the supply chain.

What is the most common use of EDI 855?

The most common use of the EDI 855 is to confirm purchase orders in retail and distribution environments, ensuring suppliers validate order details and communicate fulfillment capability before shipment.

Industry Applications

Retail & Grocery - Vendor compliance and replenishment alignment
Manufacturing - Production and inventory validation
Foodservice - Multi-site delivery coordination
Automotive - Just-in-time (JIT) scheduling adjustments
Distribution - Order orchestration across warehouses

Header-Level Acknowledgment (BAK)

Defines the overall status of the purchase order.

Code	Meaning	Business Impact
AC / AT	Accepted	Order proceeds as planned
AD	Accepted with changes	Buyer review required
RJ / RD	Rejected	Order must be corrected

Line-Level Acknowledgment (ACK)

Provides item-specific responses for each product.

Code	Meaning	Use Case
IA	Item accepted	Standard fulfillment
IB	Backordered	Partial fulfillment
IR	Item rejected	Exception handling

What is the EDI 855 used for in business?

The EDI 855 is used to confirm purchase orders before fulfillment, allowing suppliers to communicate acceptance, changes, or rejections. It ensures alignment between buyer and seller, reduces order errors, and supports accurate shipping and invoicing.

Operational Purpose

Ensure buyer and seller alignment before fulfillment.

Key Features

Header-level acknowledgment (BAK)
Line-level acknowledgment (ACK)
Pricing, quantity, and schedule adjustments
Exception messaging

Business Use Cases

Order validation
Supply chain synchronization
Exception handling
Compliance enforcement

What Information Is Required in the EDI 855?

The EDI 855 includes purchase order details, acknowledgment status, line-item responses, delivery dates, pricing, and reference information. It ensures suppliers clearly communicate whether an order is accepted, rejected, or modified, enabling accurate fulfillment and alignment with the original purchase order.

Core Information Categories

The EDI 855 organizes required information into header-level and line-level data elements to fully describe the supplier’s response.

Category	Description	Key Segments
Order Identification	Links acknowledgment to original PO	BAK, REF
Acknowledgment Status	Defines acceptance, rejection, or changes	BAK02
Party Information	Identifies buyer, seller, and ship-to	N1, N3, N4
Line Item Details	Describes products and quantities	PO1
Line-Level Response	Confirms item-level acceptance or changes	ACK
Scheduling	Provides ship/delivery dates	DTM
Financial Data	Pricing, allowances, and charges	PO1, SAC
Totals & Control	Ensures completeness and integrity	CTT, SE

Quick Segment Reference

Segment	Purpose
ST	Transaction start
BAK	Acknowledgment header
REF	Reference identifiers
N1/N3/N4	Party and location
PO1	Line items
ACK	Line acknowledgment
DTM	Dates
SAC	Charges/allowances
CTT	Totals
SE	Transaction end

Required Segments

Segment	Requirement
ST	Mandatory
BAK	Mandatory
PO1	Mandatory
ACK	Mandatory
SE	Mandatory

Required Identifiers

Purchase Order Number (BAK03) links to original EDI 850
Transaction Control Number (ST02) unique transaction identifier
Product identifiers (PO1) SKU, UPC, GTIN, or vendor item

Required Dates

PO Date (BAK04) Original order date
Acknowledgment/ship dates (DTM) confirmed ship, delivery, or availability dates

Required Financial Data

Unit price (PO1) agreed to or modified pricing
Charges/allowances (SAC) discounts, freight, or adjustments

Common Segments

Segment	Business Meaning	Notes
ST	Transaction header	Identifies 855
BAK	Acknowledgment status	Core control logic
REF	Cross-reference data	ERP/TMS linkage
FOB	Freight terms	Optional
SAC	Charges/allowances	Header or line
DTM	Scheduling dates	Critical for fulfillment
TD5	Carrier details	Optional
N1	Parties	Buyer/Seller
PO1	Line items	Required
ACK	Line response	Required
CTT	Totals	Summary

Summary Table of Key Segments

Segment	Level	Function
ST	Header	Transaction identification
BAK	Header	Overall acknowledgment status
REF	Header	Reference linking
N1 Loop	Header	Party identification
PO1	Detail	Item data
ACK	Detail	Line-level response
SAC	Header/Detail	Financial adjustments
DTM	Header/Detail	Scheduling
CTT	Summary	Totals
SE	Summary	Transaction closure

Segment-Level Notes (Specification-Aligned)

Segment	Key Elements	Notes
ST	ST01, ST02	Identifies transaction and control number
BAK	BAK01, BAK02, BAK03, BAK04	Core business control segment
REF	REF01, REF02	Cross-system reference mapping
N1/N3/N4	Name, address, location	Identifies trading partners
PO1	Quantity, price, item ID	Required for each line item
ACK	Status, quantity, date	Required for each line item
DTM	Date qualifiers	Scheduling and delivery commitments
SAC	Allowance/charge codes	Financial adjustments
CTT	Line count totals	Validates transaction completeness
SE	Segment count	Closes transaction

What is the ACK segment in EDI 855?

The ACK segment provides line-level acknowledgment details in the EDI 855, indicating item acceptance, rejection, backorder status, quantities, and expected delivery dates for each product in the purchase order.

What is the difference between header-level and line-level acknowledgment in EDI 855?

Header-level acknowledgment (BAK) defines the overall purchase order status, while line-level acknowledgment (ACK) provides item-specific responses such as accepted quantities, backorders, or rejections for each product.

What Status and Reason Codes Are Used with the EDI 855?

The EDI 855 uses status codes (BAK02) to indicate the overall purchase order response and reason/line codes (ACK01) to define item-level outcomes. Together, they communicate whether an order is accepted, rejected, or modified, and how each individual item will be fulfilled.

What is BAK02 in EDI 855?

BAK02 is the acknowledgment type code in the EDI 855 that indicates whether a purchase order is accepted, rejected, or accepted with changes. Common values include AC (accepted), AD (accepted with detail), and RJ (rejected).

Status Codes (BAK02)

Code	Meaning	Business Interpretation	When Used
AC	Accepted	Order accepted (often with detail)	Standard acceptance
AT	Accepted	Order accepted as-is	No changes required
AD	Accepted with Detail	Accepted with line-level changes	Quantities, dates, pricing adjusted
AK	Accepted (No Detail)	Accepted without line detail	Minimal acknowledgment
RJ	Rejected	Entire order rejected	Cannot fulfill
RD	Rejected with Detail	Rejected with explanation	Detailed rejection context provided

Reason Codes (ACK01)

Code	Meaning	Business Interpretation	Use Case
IA	Item Accepted	Item will be fulfilled as requested	Standard fulfillment
IB	Item Backordered	Item delayed due to availability	Partial fulfillment
IR	Item Rejected	Item cannot be fulfilled	Discontinued or unavailable

What are the Benefits of the EDI 855?

The EDI 855 improves supply chain accuracy by confirming purchase orders before fulfillment. It reduces errors, enhances visibility into supplier commitments, supports compliance with trading partner requirements, and ensures alignment between buyers and suppliers on quantities, pricing, and delivery timelines.

Why is the EDI 855 important?

The EDI 855 improves supply chain accuracy by confirming order details before fulfillment. It reduces errors, prevents chargebacks, enhances visibility into supplier commitments, and ensures compliance with trading partner requirements.

Operational Benefits

The EDI 855 strengthens execution by validating orders before shipment.

Benefit	Description	Operational Impact
Order Accuracy	Confirms quantities, pricing, and items before fulfillment	Reduces incorrect shipments
Early Exception Detection	Identifies issues such as backorders or rejections	Prevents downstream disruptions
Workflow Automation	Eliminates manual confirmations (email, phone, fax)	Accelerates order processing
Supplier Commitment Visibility	Provides confirmed delivery and fulfillment details	Improves planning and coordination
Reduced Rework	Minimizes need for order corrections post-shipment	Increases operational efficiency

Financial Benefits

The EDI 855 directly impacts cost control and financial accuracy.

Benefit	Description	Financial Impact
Fewer Chargebacks	Prevents non-compliant or incorrect shipments	Reduces penalty costs
Invoice Accuracy	Aligns PO and invoice data before billing	Minimizes disputes
Reduced Returns	Ensures correct items are shipped	Lowers reverse logistics costs
Cost Avoidance	Identifies issues before fulfillment	Avoids costly corrections

Compliance Benefits

The EDI 855 supports adherence to trading partner and industry requirements.

Benefit	Description	Compliance Impact
SLA Adherence	Ensures timely acknowledgment of orders	Maintains vendor compliance
Standardized Communication	Uses structured EDI formats	Reduces misinterpretation
Audit Trail	Provides documented acknowledgment history	Supports audits and reporting
Retail Compliance	Meets retailer/vendor program requirements	Avoids penalties and delisting

Supply Chain Coordination Benefits

The EDI 855 enables synchronized execution across trading partners.

Benefit	Description	Coordination Impact
Buyer-Supplier Alignment	Confirms shared understanding of order terms	Reduces miscommunication
Inventory Planning	Provides early visibility into fulfillment capability	Improves stock management
Logistics Readiness	Aligns shipping schedules and expectations	Reduces delays
Multi-Partner Coordination	Supports complex supply chain networks	Improves orchestration

Visibility & Control Benefits

The EDI 855 enhances transparency across the order lifecycle.

Benefit	Description	Visibility Impact
Real-Time Status Updates	Communicates order acceptance or changes	Improves decision-making
Exception Monitoring	Highlights backorders, rejections, or delays	Enables proactive response
Performance Tracking	Measures supplier responsiveness and accuracy	Supports continuous improvement
Execution Control	Provides confirmation before fulfillment begins	Strengthens operational governance

Exception Management Benefits

The EDI 855 enables structured handling of disruptions.

Benefit	Description	Outcome
Backorder Identification	Flags unavailable items early	Adjusts expectations
Rejection Handling	Provides structured rejection responses	Speeds resolution
Change Management	Communicates updates to order details	Maintains alignment
Alerting & Notifications	Triggers system alerts for exceptions	Improves responsiveness

Industry-Specific Benefits

Retail & Grocery - Ensures vendor compliance and replenishment accuracy
Manufacturing - Aligns production planning with order demand
Automotive - Supports just-in-time (JIT) fulfillment
Foodservice - Enables multi-location delivery coordination
Distribution - Improves order orchestration across networks

Before vs After EDI 855 (Business Impact)

Scenario	Without EDI 855	With EDI 855
Order Confirmation	Manual (email/phone)	Automated (EDI)
Error Detection	After shipment	Before shipment
Visibility	Limited	Real-time
Compliance	Inconsistent	Enforced
Dispute Resolution	Reactive	Proactive

What are the Benefits of Automating the EDI 855?

Category	Benefit	Impact
Automation	ERP integration	Faster processing
Visibility	Real-time acknowledgment	Better planning
Exception Handling	Automated alerts	Reduced disruptions
Compliance	Rule enforcement	Fewer penalties

Are there Regulatory and Compliance Requirements for the EDI 855?

No federal mandate
Strong trading partner enforcement
Retail compliance programs drive adoption

EDI 855 Technical Structure, Format, and Versions

Hierarchical Loop Structure

Header: ST → BAK → REF → N1
Detail: PO1 → ACK → DTM
Summary: CTT → SE

File Format and Delimiters

Using the following Production Delimiters on all EDI transmissions sent to Vendors, Carriers, Trading and Solution partners will enable consistent EDI parsing across trading partners:

Segment Separator – hex 15 (NAK) or hex 7E (~)
Element separator – hex 7C (|) or hex 2A (*)
Sub-element Separator – hex 3E (>)

Version Differences

The most widely implemented version of the EDI 855 is X12 v4010, followed by v5010 which support expanded data requirements and improved and expanded validation, compliance, and unique identification capabilities (GTIN, GLN, EPCIS)

v4010 - Most widely implemented
v5010 - Expanded validation and compliance

What are the Limitations of the EDI 855?

The EDI 855 is limited by rigid standards, trading partner dependencies, and delayed communication timing. It provides structured acknowledgment but lacks real-time responsiveness, flexibility for complex scenarios, and consistency across implementations, requiring careful integration and governance to avoid errors and delays.

Category	Key Limitation	Business Risk
Standardization	Partner-specific variations	Increased complexity
Speed	Not real-time	Delayed decisions
Flexibility	Rigid format	Limited adaptability
Compliance	Partner dependency	Inconsistent execution
Integration	Complex mapping	High implementation cost
Visibility	Limited error detail	Slower resolution

Version Constraints

Rigid structure tied to implementation guides

Timing Limitations

Dependent on SLA requirements

Data Constraints

Limited flexibility for complex scenarios

Are Implementation Guidelines and Sample Files Available for the X12 EDI 855 PURCHASE ORDER ACKNOWLEDGMENT?

Yes. PartnerLinQ provides sample transactions and implementation guides. X12 EDI 855 PURCHASE ORDER ACKNOWLEDGMENT implementation guides illustrate both inbound and outbound flows, segment layouts, and valid data examples and support testing and partner onboarding.

Companion Guides

Trading partners frequently publish X12 EDI 855 PURCHASE ORDER ACKNOWLEDGMENT implementation guidelines defining segment usage and validation rules. Customized specification documents for use in on boarding and technical development are available through PartnerLinQ Support and Guideline Management.

What does an EDI 855 example look like?

An EDI 855 example includes a structured transaction beginning with the ST segment, followed by the BAK segment for acknowledgment status, PO1 for line items, ACK for line-level responses, and ending with CTT and SE segments to summarize and close the transaction.

Sample File (X12)

ST*855*7977~

BAK*00*AC*8ZO5WG4Q*20200628~

PO1*1*12*EA*423.49~

ACK*IA*12*EA*068*20200702~

CTT*1*12~

SE*6*7977~

What are the more common EDI errors and rejection scenarios?

Common EDI 855 errors include structural failures, invalid data, missing identifiers, incorrect status codes, and trading partner rule violations. These errors can lead to rejected transactions, delayed order processing, incorrect shipments, and compliance penalties if not identified and resolved early.

Category	Error Type	Description	Business Impact
Structural	Missing Required Segment	Mandatory segment not included	Transaction fails to process
Structural	Segment Order Error	Incorrect segment sequencing	Transaction rejected
Structural	Segment Count Mismatch	SE01 does not match actual segments	Transaction rejected
Structural	Invalid Delimiters	Incorrect separators used	File unreadable
Data Validation	Invalid Code Value	Unsupported BAK02 or ACK01 value	Misinterpretation or rejection
Data Validation	Incorrect Format	Invalid date or numeric format	Processing failure
Data Validation	Missing Required Data	Required field not populated	Rejection
Data Validation	Invalid Quantity	Quantity mismatch or negative value	Inventory errors
Identifier	PO Number Mismatch	PO does not match original 850	Order cannot be linked
Identifier	Item ID Mismatch	Product identifiers inconsistent	Incorrect fulfillment
Identifier	Partner ID Error	Sender/receiver mismatch	Delivery failure
Compliance	Version Mismatch	Incorrect X12 version	Transaction rejected
Compliance	Companion Guide Violation	Partner-specific rules not followed	Non-compliance
Compliance	Code Misalignment	Incorrect qualifier usage	Processing errors
Line-Level (ACK)	Missing ACK Segment	No item-level response provided	Incomplete acknowledgment
Line-Level (ACK)	Incorrect ACK Code	Wrong status assigned	Misleading fulfillment
Line-Level (ACK)	Quantity Mismatch	ACK quantity differs from PO1	Inventory issues
Line-Level (ACK)	Missing Dates	No delivery or availability date	Scheduling delays
Timing	Late Acknowledgment	855 sent after SLA window	Compliance penalties
Timing	Missing 855	No acknowledgment sent	Order uncertainty
Timing	Duplicate 855	Multiple acknowledgments sent	Confusion
Business Logic	Incorrect BAK02 Usage	Wrong header status	Misalignment
Business Logic	Header/Line Conflict	BAK and ACK inconsistent	Data inconsistency
Business Logic	Missing Rejection Detail	No explanation for rejection	Slow resolution
Financial	Price Mismatch	Price differs from agreement	Disputes
Financial	Missing SAC Data	Charges/allowances omitted	Billing errors
Financial	Incorrect Allowance Code	Wrong SAC qualifier used	Revenue impact

What are the Basic Questions for EDI Integration with the 855?

Are there Samples and Specs available?
What is the general direction of the transaction?
Are inbound or outbound orders required?
Are AS2, VAN, or SFTP connections used?
Are more than one trading partner exchanging the [Transaction ID]?
Are there other interested parties?
What trading partner requirements apply?
What version is supported?
What other transactions might these interested parties be a party to?
What response to the [Transaction ID] is expected or sent?
Is a response to [Transaction ID] a timed event? Are notifications involved/needed?
What system generates the response?
What timing SLAs apply?
Which systems generate the response?
What response time is contractually required?
What response is expected (AC, AD, RJ)?
Are there samples and specs of the response transaction available?
Are change orders supported?
What validation rules are required?
What validation rules apply?
How are changes to the [Transaction ID] business message managed today?
Is there automation? (an internal system trigger) or are [Transaction ID] business message transactions triggered manually?
How is automation managed (manual vs. system-triggered)?
How are changes and exceptions managed?
Are responses and changes automatically triggered? (an internal system trigger)
Are alerting systems configured for missed response deadlines?
Do transactions require human intervention?
What systems generate or consume the transaction?
How are changes to the business message managed today?
How are one-time addresses handled in ERP?
Are SKU or UPC identifiers used?
What identifiers are required (SKU, UPC, GTIN)?
What testing process is required?
What validation rules must be applied?

What are the Best Practices for using the EDI 855?

Category	Best Practice	Business Impact
Accuracy	Validate PO before acknowledgment	Reduces disputes
Timeliness	Respond within SLA	Improves compliance
Visibility	Capture rejection reasons	Enables correction
Automation	Integrate ERP updates	Faster fulfillment
Consistency	Standardize codes	Easier partner alignment

What Transactions are associated with the EDI 855?

Stage	Transaction	Purpose
Order	850	Purchase Order
Acknowledgment	855	Confirmation
Change	860	PO Adjustment
Shipment	856	ASN
Invoice	810	Billing
Payment	820	Remittance

EDI 855 vs Other Acknowledgments

The EDI 855 differs from 997 and 999 acknowledgments by validating the purchase order at the business level. While 997 and 999 confirm structure and compliance, the 855 confirms whether the order is accepted, rejected, or modified.

Transaction	Purpose	Key Difference
997	Syntax acknowledgment	Confirms structure only
999	Implementation validation	Confirms compliance
855	Business acknowledgment	Confirms acceptance or changes