EDI 850 vs 855 vs 856: Complete Guide for Vendors

If you're a supplier working with retailers like Walmart, Target, or Amazon, you'll encounter three core EDI transaction types: 850 Purchase Orders, 855 PO Acknowledgments, and 856 Advance Ship Notices. Understanding the differences between these transactions and when to use each is critical for smooth operations and compliance.

The Complete EDI Workflow Sequence

Here's how these three transaction types work together in a typical retail supply chain:

EDI 850: Purchase Order (PO)

What It Is

The 850 Purchase Order is sent by the buyer (retailer) to the supplier. It's the first step in the EDI transaction workflow. The 850 tells you what the buyer wants to purchase, how much, when it needs to arrive, and where to ship it.

Key Information in an 850

• Purchase Order Number (BEG segment): Unique PO identifier
• Buyer and Ship-To Information (N1 segments): Store or DC address
• Must Arrive By Date (DTM*002 segment): Critical delivery deadline
• Line Items (PO1 segments): SKUs, quantities, unit prices
• Department Numbers (Walmart-specific): Department classification codes

Example 850 Snippet

BEG*00*SA*PO123456*********20250115~
DTM*002*20250127~
N1*ST*WALMART DC 6023*9*123456789~
PO1*1*500*EA*12.50*PE*BP*SKU789012~

Translation: Purchase order PO123456 issued on January 15, 2025. Must arrive by January 27, 2025. Ship to Walmart DC 6023. Line item 1: 500 units at $12.50 each, SKU 789012.

When to Use the 850

You don't send the 850 — the retailer sends it to you. Your job is to parse the 850 to extract order details and prepare your fulfillment process.

EDI 855: Purchase Order Acknowledgment

What It Is

The 855 Purchase Order Acknowledgment is sent by the supplier (you) back to the buyer (retailer) in response to the 850. The 855 confirms whether you accept, reject, or modify the purchase order. Many retailers require an 855 response within 24 hours of receiving the 850.

EDI 855 Acknowledgment Codes

The 855 uses acknowledgment codes in the ACK segment to indicate order status:

• IA (Accepted): Order accepted as-is with no changes
• IB (Backordered): Items accepted but will ship late
• IC (Accepted with Changes): Order accepted but with quantity or date modifications
• ID (Deleted): Specific line items removed from order
• IR (Rejected): Order rejected entirely

Example 855 Snippet

BAK*00*AC*PO123456*20250115~
ACK*IA*500*EA~
DTM*010*20250127~

Translation: Acknowledgment for PO123456. IA = Accepted as-is. 500 units confirmed. Expected ship date January 27, 2025.

When to Use the 855

Send the 855 immediately after receiving and validating the 850 PO. The 855 confirms what you will ship in the future based on inventory availability, production capacity, and lead times.

EDI 856: Advance Ship Notice (ASN)

What It Is

The 856 Advance Ship Notice is sent by the supplier (you) to the buyer (retailer) when the shipment is ready to ship or has already shipped. The 856 provides detailed information about what is physically shipping: carrier, tracking number, pallet quantities, SSCC barcodes, and packaging hierarchy.

Key Information in an 856

• Shipment Identification (BSN segment): Unique shipment ID and PO reference
• Carrier and Tracking (TD5, REF segments): Carrier SCAC code, PRO number, tracking
• SSCC Barcodes (MAN segment): 18-digit pallet/carton identifiers scanned at receiving
• Hierarchical Structure (HL segments): Shipment → Order → Pack → Item levels
• Expected Delivery Date (DTM*011 segment): When the shipment will arrive

Example 856 Snippet

BSN*00*SHP987654*20250120*1430~
HL*1**S~
TD5*2*SCAC*FEDX~
REF*BM*PRO123456789~
HL*2*1*O~
PRF*PO123456~
HL*3*2*P~
MAN*GM*00123456789012345678~
HL*4*3*I~
LIN**BP*SKU789012~

Translation: Shipment SHP987654 sent January 20, 2025. Carrier: FedEx. Tracking: PRO123456789. PO: PO123456. SSCC: 00123456789012345678. Item: SKU789012.

When to Use the 856

Send the 856 when the shipment is ready to ship or has already shipped. The 856 details what is currently shipping, not what you plan to ship in the future (that's the 855's job).

Key Differences: 850 vs 855 vs 856

Common Mistakes Vendors Make

Mistake 1: Sending 856 Instead of 855

Some vendors skip the 855 acknowledgment and jump straight to the 856 when shipping. This violates many retailers' EDI requirements and can result in compliance penalties. Always send the 855 first to confirm order acceptance, then send the 856 when shipping.

Mistake 2: Sending 855 with Incorrect Acknowledgment Codes

Using "IA" (Accepted) when you actually need to use "IC" (Accepted with Changes) or "IB" (Backordered) causes downstream errors. If you can't fulfill the full quantity or need to change the ship date, use the correct code and specify the changes in the 855.

Mistake 3: Mismatched Data Between 850, 855, and 856

The PO number, SKUs, and quantities must match across all three transaction types. If the 850 requests 500 units, the 855 confirms 500 units, but the 856 ships 450 units, this creates a data mismatch that triggers compliance errors and chargebacks.

Mistake 4: Late or Missing 855 Acknowledgments

Many retailers auto-cancel POs if they don't receive an 855 acknowledgment within 24 hours. Set up automated 855 generation in your EDI system to avoid missed orders.

Mistake 5: Sending 856 After Shipment Arrives

The 856 is an advance ship notice. It must be sent before or at the time of shipment, not after the shipment has already arrived at the DC. Sending late 856s defeats the purpose of advance notification and results in chargebacks.

How PlainEDI Helps

PlainEDI converts EDI 850, 855, and 856 files to CSV instantly so you can:

• Parse 850 POs: Extract order details, MABD dates, and ship-to locations into a spreadsheet for order processing
• Validate 855 Acknowledgments: Verify acknowledgment codes and quantities before sending to retailers
• Verify 856 ASNs: Check SSCC barcodes, pallet quantities, and shipment details before sending to avoid compliance errors

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