What an EDI 855 is
The 855 is the supplier's acknowledgment of a buyer's purchase order. X12 describes it as the seller's acknowledgment of an 850, and adds that it can also tell the buyer about an order the vendor created. In X12's supply chain flow, the supplier sends it after its own system has processed the 850, to confirm the order or to change it.
Each buyer's guide sets when the 855 is due. Dot Foods, for example, asks for the first 855 within 24 hours of the purchase order and accepts updates until the order ships.
The 855 segment by segment
This table follows the example in the viewer above, which acknowledges the order on the 850 page:
| Segment | What it carries | In the example |
|---|---|---|
| ISA | The interchange header: sender and receiver IDs, date and time, the control number, and the delimiters | ISA*00* *00* *ZZ*QUILLFIELD *ZZ*FERROVA... |
| GS | The functional group header: the group code, the version, and the group control number | GS*PR*QUILLFIELD*FERROVALE*20261006*1105*552*X*004010~ |
| ST | The start of one transaction set, with its number and control number | ST*855*0001~ |
| BAK | The acknowledgment: purpose, acknowledgment type, the purchase order number and date, the seller's order number, and the date | BAK*00*AC*4500012345*20261005****SO-77120*20261006~ |
| REF | A reference number, named by its qualifier | REF*IA*V-20417~ |
| N1 | A party, such as the ship-to | N1*ST*Ferrovale Industrial Supply*92*DC-COLUMBUS~ |
| PO1 | The order line being acknowledged, as the buyer sent it | PO1*1*12*EA*412.50**BP*FIS-71402*VP*QE-1614-8-SS~ and 3 more |
| ACK | The line's status, quantity, and date. A line can carry more than one | ACK*IA*12*EA*068*20261014~ and 4 more |
| CTT | The number of lines and a hash total of the quantities | CTT*4*94~ |
| SE | The end of the set: the number of segments from ST to SE, and ST's control number | SE*15*0001~ |
| GE and IEA | The ends of the group and the interchange, each with its count and control number | GE*1*552~ |
Acknowledgment types and line status codes
BAK02 says how much the 855 covers. The meanings below come from the public guides of 3M, SAP Business Network, and other buyers:
| BAK02 | Meaning |
|---|---|
| AC | Acknowledged with detail and changes |
| AD | Acknowledged with detail, no change |
| AE | Acknowledged with exception detail only |
| AK | Acknowledged, no detail or change |
| AT | Accepted |
| RD | Rejected, with detail |
| RJ | Rejected, no detail |
ACK01 gives each line's status. These codes appear in 3M's 855 guide:
| ACK01 | Line status |
|---|---|
| IA | Item accepted |
| IB | Item backordered |
| IC | Item accepted, changes made |
| ID | Item deleted |
| IP | Item accepted, price changed |
| IQ | Item accepted, quantity changed |
| IR | Item rejected |
| DR | Item rescheduled |
| IH | Item on hold |
The example explained
BAK*00*AC*4500012345*20261005****SO-77120*20261006~acknowledges purchase order 4500012345 of October 5, 2026 with type AC, detail and changes. BAK08 carries the supplier's order number, SO-77120, and BAK09 the date of the acknowledgment, October 6, 2026, the pattern Insight's 855 guide shows.- Lines 1, 3, and 4 are accepted in full, with ACK04 068, current scheduled ship, set to October 14, 2026.
- Line 2 ordered 20. Two ACK segments split it: 12 accepted to ship October 14, 2026, and 8 backordered to November 4, 2026. The two quantities add up to the 20 ordered, as Insight's guide asks for a partial backorder.
The viewer totals the statuses: 86 units accepted and 8 backordered.
Check emailed orders line by line before you confirm them
ThriveAI's order desk reads purchase orders that arrive by email and matches each line to your items and prices. It drafts the ERP order for a person to approve. Derik will tell you what a four-week build would cover.
See order desk automation855 vs 997
The 997 and the 855 answer different questions. X12 says the 997 reports the syntax check only: the file arrived and parsed. The 855 is the business answer, line by line, such as a quantity on backorder or a new ship date. SAP Business Network returns a 997 on receipt and reports business errors separately, which shows the same split.
Dates in the 855
Each ACK segment can carry a date, with its qualifier in ACK04. SAP Business Network's guide uses 068, current schedule ship. Insight's guide pairs 055, confirmed, with accepted lines and 068 with backordered ones. The date a supplier commits to here is the date the buyer plans around, so send a new 855 when it moves.
How an 855 updates the buyer's purchase order
On the buyer's side, the 855 updates each line of the open purchase order: the confirmed quantity, the promised ship date, and any changed price. A backordered line stays open for the rest, so planning and receiving know what to expect. The guide to the backorder covers how to handle the open quantity.
Common 855 problems
- ACK quantities that do not add up. When a line is split, the ACK quantities should total the ordered quantity, or the buyer cannot tell what happened to the rest.
- A line with no ACK. With detail types such as AC, a line left out leaves its status unknown. The viewer flags it.
- The wrong type. AD says no change. Use AC when a line is backordered, rescheduled, or repriced.
- A late 855. Send it inside the window the buyer's guide sets, and send an update when a date moves.
- The wrong order. BAK03 has to repeat the purchase order number from BEG03 of the 850, or the buyer cannot match the answer to its order.
Where the 855 sits in order to cash
The 855 follows the 850 and comes before the 856 ship notice and the 810 invoice. The guide to the order to cash process covers the whole cycle.
Acknowledgments with AI
An 855 needs someone to check stock and dates for each line before it goes out. For orders that arrive by email, ThriveAI's order desk drafts the ERP order for a person to approve. Drafting the acknowledgment for a person to send is one of the steps that can come after it.