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’s inventory and fulfillment status fields.
Missing or incorrect promised ship dates — When using the IB (backordered) or IC (changed) ACK codes, the buyer expects a confirmed date in the DTM segment. A backorder acknowledgment without a promised ship date is operationally useless and may be treated as a rejection by the buyer’s system.
PO number mismatch — The PO number in the BAK segment of the 855 must exactly match the PO number from the original EDI 850. Any reformatting or truncation causes the buyer’s system to fail to match the acknowledgment to the open order, leaving the PO in an unacknowledged state.
Acknowledging discontinued or inactive SKUs with IA — If an item is discontinued and will not ship, it must be acknowledged with IR (rejected), not IA. Accepting a line you cannot fulfill is the leading cause of missed shipment chargebacks on EDI 855 transactions.
Sending the 855 before checking live inventory — Acknowledging an order as fully accepted before your ERP confirms actual availability creates a commitment you may not be able to honor. Always trigger 855 generation after an inventory validation runs in your system.

What Happens After an EDI 855 Is Sent

Once the buyer receives the 855:

They send an EDI 997 Functional Acknowledgment
Inventory planning is updated
Receiving expectations are set
Shipping and billing proceed

The order is now officially “real.”

FAQs

Q1: Who sends the EDI 855 and who receives it?

The EDI 855 is sent by the supplier, vendor, or manufacturer. It is received by the buyer, retailer, or distributor. The flow is always a supplier back to the buyer, in direct response to an incoming EDI 850 Purchase Order. The EDI 855 is never sent without a corresponding EDI 850.

Q2: What is the difference between an EDI 855 and an EDI 997?

The EDI 997 (Functional Acknowledgement) is a technical confirmation that the EDI 855 file was received without syntax errors. The EDI 855 is the business-level response which tells the buyer whether the supplier accepts, rejects, or proposes changes to the order at the line-item level. Both documents serve different purposes and are both typically required.

Q3: How long does a supplier have to send an EDI 855?

Response windows vary by trading partner. Most major retailers require an EDI 855 within 24 to 48 hours of transmitting the EDI 850. Walmart and Target typically enforce a 24-hour window. Missing the acknowledgment deadline can result in the retailer automatically cancelling the order, re-issuing it, or applying a compliance chargeback to the supplier’s account.

Q4: What happens if a supplier does not send an EDI 855?

If a supplier fails to send an EDI 855 within the trading partner’s required window, the retailer’s system typically flags the PO as unacknowledged. Depending on the retailer, the order may be automatically cancelled and reissued, a compliance violation may be logged against the supplier’s scorecard, or a financial chargeback may be applied. Some retailers also interpret a missing 855 as a rejection and source the product elsewhere.

Q5: What do the ACK codes in an EDI 855 mean?

The ACK segment in an EDI 855 contains a two-character status code for each line item from the original EDI 850. The most common codes are: IA (item accepted as ordered), IC (item accepted with a change to quantity, price, or date), IB (item backordered — will ship later), IR (item rejected — will not ship), and IS (item substituted — a different item will be sent). Each code tells the buyer’s system exactly how to update the open PO.

Q6: Can a supplier partially accept an EDI 855?

Yes. The EDI 855 supports mixed responses at the line-item level. A supplier can accept some lines with IA, backorder others with IB, reject discontinued SKUs with IR, and flag quantity changes with IC — all within the same 855 transaction. This is the primary advantage of the EDI 855 over a simple yes/no acknowledgment.

Q7: What is the difference between an EDI 855 and an EDI 860?

The EDI 855 is a supplier response to a buyer’s purchase order. The supplier uses it to accept, reject, or propose changes. The EDI 860 (Purchase Order Change Request) is a buyer-initiated document which is used by the buyer to modify a PO that has already been sent. If the 855 contains proposed changes the buyer agrees to, the buyer may send an EDI 860 to formally update the order rather than issuing a new PO.

Q8: What triggers an EDI 855?

An EDI 855 is triggered by the receipt of an EDI 850 Purchase Order. In automated systems, the 855 is generated by the supplier’s EDI platform as soon as the 850 is validated and processed against the ERP’s inventory data. The response is automatic with no manual review required for clean orders. Exceptions (backordered or rejected lines) may trigger an internal workflow for review before the 855 is transmitted.

Q9: What is a chargeback related to EDI 855?

An EDI 855-related chargeback is a financial penalty applied by a retailer when a supplier fails to comply with their acknowledgment requirements. Common triggers include: failing to send the 855 within the required response window, sending an order-level acknowledgment when line-level is required, using the wrong ACK code (e.g., accepting a line that ships short), and failing to include promised ship dates on backordered lines. Chargeback amounts vary by retailer — they can be a flat fee per violation or a percentage of the invoice value.

Q10: Does an EDI 855 replace the EDI 997?

No. The EDI 997 (Functional Acknowledgement) and the EDI 855 (Purchase Order Acknowledgement) are separate documents that serve different functions. The 997 is a system-level confirmation that the EDI file arrived intact. The 855 is the business-level response from the supplier. Most trading partners require both — the 997 confirms technical receipt, and the 855 confirms commercial commitment.

Q11: How does the EDI 855 work in a drop-ship model?

In drop-ship, the retailer sends an EDI 850 with the end consumer’s shipping address in the ship-to field. The supplier’s EDI 855 response must be returned quickly within 24 hours because the consumer is already expecting delivery. Drop-ship 855s typically involve single-unit line items, require a confirmed ship date in the DTM segment, and often include a carrier code so the retailer can provide tracking information to the consumer.

Q12: What ERP systems can generate EDI 855 acknowledgments automatically?

ERP systems like NetSuite, SAP, Acumatica, and QuickBooks do not generate EDI 855 files natively. You need to integrate your ERP with an EDI platform like Elevate that reads your inventory and order confirmation data, applies your ACK code logic, maps the output into the correct EDI 855 format, and transmits it to your trading partner automatically when an EDI 850 is received.

Q13: What is the EDI 855 order-to-cash cycle position?

The EDI 855 is the second step in the order-to-cash cycle:

(1) Buyer sends EDI 850 Purchase Order.

(2) Supplier sends EDI 997 to confirm technical receipt.

(3) Supplier sends EDI 855 to acknowledge the order at the line level.

(4) Supplier picks, packs, and ships confirmed lines.

(5) Supplier sends EDI 856 Advance Ship Notice when goods depart.

(6) Supplier sends EDI 810 Invoice requesting payment.

(7) Buyer performs a three-way match and releases payment.

Q14: How do I set up EDI 855 with Walmart?

To send EDI 855 acknowledgments to Walmart: download Walmart’s EDI implementation guide from Retail Link; set up AS2 connectivity or connect through a Walmart-approved VAN; build your 855 map to Walmart’s specifications, including mandatory line-level ACK coding; connect your ERP so acknowledgments generate automatically from inventory data when a 850 is received; and complete Walmart’s EDI testing cycle before going live. Walmart enforces a strict 24-hour response window — manual processes cannot reliably meet this SLA. A managed EDI provider like Elevate has pre-built Walmart maps ready to deploy.