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Home > EDI Codes > EDI 855

EDI 855 Purchase Order Acknowledgement

EDI 855 Definition

An EDI 855 Purchase Order Acknowledgement is an electronic document that is used by sellers to confirm receipt, reject, or request modification of a purchase order (EDI 850) back to the buyer or trading partner. The buyer knows that the supplier is ready to fulfill the order and ship the goods by the date as requested.

The EDI 855 is sent by the supplier and received by the buyer or retailer. It is always sent in direct response to an incoming EDI 850 Purchase Order. Most major retailers require the EDI 855 to be transmitted within 24 to 48 hours of receiving the 850.

Sent by: Supplier / Vendor / Manufacturer Received by: Buyer / Retailer / Distributor

Response document: EDI 997 (Functional Acknowledgement)

What EDI 855 Represents in Real Life

EDI 855 is the commitment checkpoint in the order lifecycle.

Until the 855 is sent:

    • Buyers do not know if inventory is truly available
    • Production schedules may still be uncertain
    • Delivery expectations are not locked in

Once the 855 is received:

    • Buyers can plan downstream inventory
    • Retailers can forecast store replenishment
    • Distributors can communicate availability internally
    • Exceptions are handled early, not after shipping fails

This is where surprises are either prevented or created.

EDI 855 Specification

This X12 Transaction Set contains the format and establishes the data contents of the Purchase Order Acknowledgment Transaction Set (855) for use within the context of an Electronic Data Interchange (EDI) environment. The transaction set can be used to provide for customary and established business and industry practice relative to a seller’s acknowledgment of a buyer’s purchase order. This transaction set can also be used as notification of a vendor generated order. This usage advises a buyer that a vendor has or will ship merchandise as prearranged in their partnership.

Source: Accredited Standards Committee X12. ASC X12 Standard [Table Data]. Data Interchange Standards Association, Inc., Falls Church, VA. https://x12.org/node/4397

Components of an EDI 855 Purchase Order Acknowledgement include:

  •   Purchase order number & Date
  •   Shipping & delivery Details & instructions
  •   Item/Service Identifiers (UPC/EAN/GTIN)
  •   Order and item status (i.e. accepted, rejected, or backordered)

EDI 855 can also include:

  •   Item Price and Quantity
  •   Name & Address of the Buyer
  •   Name & Address of the Supplier
  •   Any additional terms for the sale, such as discounts, etc

How the EDI 855 Fits into the Full Document Flow

The EDI 855 sits directly between ordering and fulfillment:

  • EDI 850 – What the buyer requested
  • EDI 855 – What the seller commits to
  • EDI 856 – What actually ships
  • EDI 810 – What is billed
  • EDI 820 – What is paid

If the 855 is skipped or inaccurate, everything downstream is at risk.

  • EDI 810 – Invoice 
  • EDI 856 – Advance Ship Notice
  • EDI 850 – Purchase Order
  • EDI 860 –  Order Change Request 
  • EDI 812 – Credit / Debit Adjustment
  • EDI 820 – Payment or Order Remittance 
  • EDI 832 – Price/Sales Catalog
  • EDI 830 – Planning Schedule with Release Capability
  • EDI 846 – Inventory Inquiry
  • EDI 867 – Product Transfer and Resale Report File Format
  • EDI 870 – Order Status Report
  • EDI 875 – Grocery Products Purchase Order
  • EDI 990 – Response to a Load Tender
  • EDI 997 – Functional Acknowledgment

EDI 855 Sample File Format (Raw EDI File)

ISA*00*          *00*          *01*789456123      *01*943556183      *180305*1433*U*00401*000001199*0*P*>
GS*PR*789456123*943556183*20180305*1433*1199*X*004010
ST*855*4321
BAK*00*AT*345678910*20180305
REF*VR*4567890000
N1*ST*UNFI Aurora*9*9435561830035
N3*17901 East 40th Ave
N4*Aurora*CO*80011
PO1**2*CA*99.04**MF*176427*PI*21382*UA*076566711069*UI*76566711069*UK*10765667110697
ACK*IA*2*CA*068*20180319**MF*176427*PI*21382*UA*076566711069*UI*76566711069*UK*10765667110697
PO1**42*CA*90.79**MF*52793*PI*21389*UA*076566752793*UI*76566752793*UK*00765667527931
ACK*IA*42*CA*068*20180319**MF*52793*PI*21389*UA*076566752793*UI*76566752793*UK*00765667527931
PO1**36*CA*91.63**MF*100707*PI*21692*UA*076566710070*UI*76566710070*UK*00765667100707
ACK*IA*36*CA*068*20180319**MF*100707*PI*21692*UA*076566710070*UI*76566710070*UK*00765667100707
PO1**3*CA*97.9**MF*166427*PI*17545*UA*076566711001*UI*76566711001*UK*00765667110010
ACK*IA*3*CA*068*20180319**MF*166427*PI*17545*UA*076566711001*UI*76566711001*UK*00765667110010
PO1**28*CA*91.22**MF*11020*PI*29624*UA*076566711020*UI*76566711020*UK*00765667110201
ACK*IA*28*CA*068*20180319**MF*11020*PI*29624*UA*076566711020*UI*76566711020*UK*00765667110201
PO1**217*CA*91.63**MF*176184*PI*52505*UA*076566711059*UI*76566711059*UK*00765667110591
ACK*IA*217*CA*068*20180319**MF*176184*PI*52505*UA*076566711059*UI*76566711059*UK*00765667110591
PO1**217*CA*91.63**MF*176345*PI*52507*UA*076566711060*UI*76566711060*UK*00765667110607
ACK*IA*217*CA*068*20180319**MF*176345*PI*52507*UA*076566711060*UI*76566711060*UK*00765667110607
PO1**406*CA*24.884**MF*011010340*PI*25806***UA*079452221012*UK*00794522210121
ACK*IC*376*CA*068*20180326**MF*011010340*PI*25806***UA*079452221012*UK*00794522210121
PO1**290*CA*91.63**MF*176378*PI*52508*UA*076566711067*UI*76566711067*UK*00765667110676
ACK*IA*290*CA*068*20180319**MF*176378*PI*52508*UA*076566711067*UI*76566711067*UK*00765667110676
PO1**18*CA*95.4**MF*177985*PI*85666*UA*076566711075*UI*76566711075*UK*00765667110751
ACK*IA*18*CA*068*20180319**MF*177985*PI*85666*UA*076566711075*UI*76566711075*UK*00765667110751
PO1**42*CA*99.6**MF*400104*PI*21420*UA*076566740010*UI*76566740010*UK*00765667400104
ACK*IA*42*CA*068*20180319**MF*400104*PI*21420*UA*076566740010*UI*76566740010*UK*00765667400104
PO1**29*CA*44.8749**MF*011069635*PI*54608***UA*076211119949*UK*00762111199492
ACK*IA*29*CA*068*20180621**MF*011069635*PI*54608***UA*076211119949*UK*00762111199492
PO1**22*CA*31.9199**MF*011019077*PI*21640***UA*076211191164*UK*00762111911643
ACK*IR*0*CA*068*20180621**MF*011019077*PI*21640***UA*076211191164*UK*00762111911643
PO1**9*CA*29.9199**MF*011019075*PI*21638***UA*076211191165*UK*00762111911650
ACK*IA*9*CA*068*20180621**MF*011019075*PI*21638***UA*076211191165*UK*00762111911650
PO1**29*CA*34.8749**MF*011010285*PI*25786***UA*079452220005*UK*00794522200054
ACK*IA*29*CA*068*20180621**MF*011010285*PI*25786***UA*079452220005*UK*00794522200054
CTT*10
SE*38*4321
GE*1*1199
IEA*1*000001199

What Each Line in EDI 855 Format Means

The raw EDI 855 file is made up of segments. Each segment serves a specific purpose in the transaction. Here is what each segment does:

Segment

What it does

ISA

Interchange header — identifies sender, receiver, date, and control number

GS

Group header — identifies the transaction type (PR = Purchase Order Acknowledgment)

ST*855

Marks the start of the 855 transaction set

BAK

Beginning acknowledgment segment — contains acknowledgment type, PO number, and acknowledgment date

CUR

Currency — specifies the transaction currency (e.g., USD)

REF

Reference numbers — vendor number, buyer’s internal identifiers, or deal/contract numbers

N1

Party identification — identifies ship-to (ST), sold-to (SO), and bill-to (BT) parties

N3 / N4

Address lines — street address, city, state, ZIP, and country

PO1

Line item detail — line number, quantity, unit of measure, unit price, and item identifiers (UPC, SKU, GTIN)

ACK

Line item acknowledgment — the status code for each PO1 line (accepted, rejected, backordered, substituted)

DTM

Date/time reference — requested ship date, delivery date, or promised date

MSG

Free-form message text — supplier notes to the buyer about specific lines or the order overall

CTT

Transaction totals — number of line items in the acknowledgment

SE

Transaction set trailer — marks the end of the 855 and contains a segment count

GE

Group trailer — closes the functional group opened by the GS segment

IEA

Interchange trailer — closes the interchange envelope opened by the ISA segment

EDI 855 Acknowledgement Status Codes Explained

The ACK segment is the heart of the EDI 855. Every line item from the original EDI 850 gets its own ACK segment with a two-character status code that tells the buyer exactly what the supplier will do with that line. Here are the most common ACK codes:

ACK code

Meaning

What the buyer should do

IA

Item accepted — quantity and price as ordered

No action needed; fulfillment proceeds

IC

Item accepted with change — quantity, price, or date differs from the PO

Review the change; accept or reject via EDI 860

IB

Item backordered — will ship on a later date

Update inventory planning; expect a delayed shipment

IR

Item rejected — supplier cannot fulfill this line

Source from another supplier; issue a new PO

IS

Item substituted — a different item will be shipped

Confirm the substitute is acceptable before shipping proceeds

IP

Item accepted on partial quantity — less than ordered quantity will ship

Update receiving expectations; re-order the shortfall if needed

IQ

Item quantity changed — supplier is changing the quantity

Verify the new quantity aligns with your minimum order requirements

IU

Item price changed — supplier is changing the unit price

Flag for AP review; may require a revised PO

How to Start Sending EDI 855 Purchase Order Acknowledgments

  • Get your trading partner’s implementation guide — Every retailer publishes their specific EDI 855 requirements. This document defines which ACK codes are valid, whether line-level acknowledgment is required, response time windows, and which segments are mandatory.
  • Set up EDI connectivity — Choose your communication method: AS2 (most common for large retailers), SFTP, or VAN. Your trading partner’s guide will specify which they require.
  • Build or configure your 855 map — Your EDI system needs a map that translates your ERP’s order confirmation data into a valid EDI 855 format per your trading partner’s specification.
  • Connect to your ERP inventory system — The real value of the EDI 855 is automating the acknowledgment based on live inventory data. When an 850 is received, your ERP should check inventory, determine line-level availability, and generate the 855 automatically without manual review.
  • Configure your ACK code logic — Work with your EDI provider to define the rules: which inventory threshold triggers a backorder vs. a rejection, how substitutions are handled, and what changes require buyer approval before the 855 is sent.
  • Test with your trading partner — Most retailers require a testing cycle before going live. You will exchange test 850s and 855s and get sign-off before production begins.
  • Go live and monitor response deadlines — Once live, monitor for incoming 850s and track your 855 response times against your trading partner’s SLA window. Missing the response window is one of the most common causes of EDI compliance chargebacks.

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Real-World Example: Distributor Sending an EDI 855

A distributor receives an EDI 850 with 25 line items.

    • Inventory is checked automatically
    • 20 lines are accepted as requested
    • 3 lines are backordered
    • 2 lines are rejected due to discontinued SKUs
    • The EDI 855 is sent within minutes

The buyer now knows:

    • What will ship immediately
    • What will ship later
    • What needs to be substituted

No phone calls. No guessing.

How EDI 855 Works Across Different Fulfillment Models

  • DC replenishment (most common): The supplier sends a single EDI 855 acknowledging the full PO sent to a distribution center. Line-level ACK codes reflect inventory availability per item. The buyer uses the 855 to update their DC receiving schedule before the goods ship.
  • Direct-to-store (DTS): When a buyer sends 850s with individual store location codes, the supplier sends a corresponding 855 for each PO. Line-level acknowledgments must be accurate at the store level — backordering one store while fulfilling another requires precise ACK coding per transaction.
  • Drop-ship: The retailer sends an EDI 850 with the end consumer’s address. The supplier’s EDI 855 must be returned quickly, often within 24 hours because the consumer is already waiting. Drop-ship 855s typically involve single-unit line items and require confirmed ship dates in the DTM segment.
  • Vendor-managed inventory (VMI): In VMI programs, the supplier often initiates the replenishment PO themselves based on inventory data from an EDI 846. When a buyer-generated 850 does arrive, the 855 response is typically an automatic full acceptance since the supplier already knows the inventory position.

Why EDI 855 Accuracy Matters

If the EDI 855 is wrong or missing:

    • Buyers expect shipments that never arrive
    • Retailers penalize suppliers for missed dates
    • Distributors oversell inventory
    • Customer service teams scramble to explain failures

A clean 855 prevents false commitments.

Common Challenges with EDI 855 Acknowledgments

  • Missing the response window — Most major retailers require an EDI 855 within 24 to 48 hours of transmitting the 850. Walmart and Target typically enforce a 24-hour window. Missing this deadline can result in automatic order cancellation or a compliance chargeback. Automate 855 generation from your ERP so the response fires as soon as the 850 is processed.

  • Order-level acknowledgment instead of line-level — Many retailers require a separate ACK segment for every PO1 line item. Sending a single order-level acceptance without line-level ACK codes causes the buyer’s system to reject the 855 or flag it for manual review. Always check the implementation guide for line-level requirements before configuring your map.

  • Wrong ACK code for the situation — Using IA (accepted) for a line that will ship short, or IB (backordered) for a line that will never ship, creates false expectations that result in chargebacks when the EDI 856 does not match. Map your ACK code logic precisely to your ERP’