The EDI 855 is the purchase order acknowledgment you send back after an 850. It tells the retailer what you will actually ship, line by line, inside their acknowledgment window. AIMS360 generates it from the live order.
An 850 tells you what a retailer wants. The 855 is how you tell them what they are actually going to get, line by line, usually within 24 hours. Get it wrong or send it late and it costs you fill rate, scorecard points and in some cases a deduction, before a single carton ships.
The EDI 855 is the transaction set a supplier sends back to a retailer to acknowledge a purchase order and state what will actually be shipped. It confirms the order was received and parsed, then reports line by line whether each item is accepted as ordered, accepted with a changed quantity or date, backordered, substituted or rejected.
It is easy to treat the 855 as a formality, a receipt. It is not. On most vendor scorecards the 855 is the document that sets the retailer's expectation, and the fill rate you are measured against is calculated from what you acknowledged, not from what was originally ordered. Acknowledging a line you cannot ship converts a supply problem into a service failure. Acknowledging honestly, and early, usually costs less.
The 855 sits between the 850 purchase order and the 856 advance ship notice. It is not the same as the 997 functional acknowledgment, which only confirms a file was received and is structurally valid. The 997 says the envelope arrived. The 855 says what is in the box.
Two places in the file decide how the retailer reads your acknowledgment: the BAK acknowledgment type at the header, and the ACK line status on each item.
| AD | Acknowledge with detail, no change. Everything ships as ordered. |
| AC | Acknowledge with detail and change. Some lines differ from the order. |
| AE | Acknowledge with exception detail only. Only the problem lines are listed. |
| AK | Acknowledge, no detail or change. Header level only. |
| RD | Reject with detail. |
| RJ | Rejected, no detail. |
| IA | Item accepted as ordered. |
| IQ | Item accepted, quantity changed. The one that quietly moves your fill rate. |
| IB | Item backordered. |
| IR | Item rejected. |
| IS | Item accepted, substitution made. |
| DR | Item accepted, date rescheduled. |
| IP | Item accepted, price pending. |
A simplified acknowledgment for one order with one changed line.
ST*855*0001 / BAK*00*AC*4500098765*20260812 / REF*DP*0042 / PO1*1*240*EA*12.50**UP*012345678905 / ACK*IA*240*EA / PO1*2*120*EA*18.00**UP*012345678912 / ACK*IQ*60*EA*20260901 / CTT*2 / SE*9*0001| ST | Opens the transaction set and names it as an 855. |
| BAK | Beginning segment. Carries the purpose code, the acknowledgment type, the retailer's purchase order number and the PO date. This is where AC, AD, AE or RJ lives. |
| REF | Reference identifiers such as department, vendor number or contract. |
| PO1 | One per ordered line: line number, quantity, unit of measure, price and the item identifier, usually a UPC or GTIN. |
| ACK | The response to the PO1 immediately above it. Status code, the quantity you are actually committing, and where relevant a revised date. |
| CTT | Transaction totals, used as a control check on line count. |
| SE | Closes the transaction set with a segment count. |
In the example above, line 1 is accepted in full and line 2 is cut from 120 to 60 units with a new date of 1 September. The retailer's system now expects 60, and your fill rate is measured against 60 rather than 120. That is the single most useful thing the 855 does for a supplier, and the reason sending it accurately matters more than sending it fast.
The 855 is one of the most widely required documents in retail EDI, and the acknowledgment window is usually the strictest timing rule a new vendor meets. Commonly required inside 24 hours of the 850 by Walmart, Target and Costco. Amazon vendor programs commonly work to a 48 hour window. Kohl's includes it in its core set.
It is not universal. Macy's and Bloomingdale's publish an 855 mapping guide but do not list it among the documents required from all vendors, which is a useful reminder that a document existing in a retailer's guide is not the same as that retailer requiring it from you. Always work from the guideline issued to your own vendor account.
The most common failure, and the most expensive. A system configured to acknowledge every line IA regardless of stock produces a clean acknowledgment and then a short shipment. The retailer measured you against what you promised. A cut acknowledged on day one is a conversation. The same cut discovered at the dock is a chargeback and a fill rate hit.
Miss the window and the order sits unconfirmed. Some retailers escalate to a buyer, some auto-cancel, some simply record it against your scorecard. The window starts when the 850 lands on their side, not when someone opens it, which is why acknowledgment has to be automatic rather than a task in someone's morning.
If the 855 says 60, the 856 ships 45 and the 810 bills 60, you have created a three way mismatch by hand. Retailers that run automated matching will hold payment on it. Three documents generated from three systems is how that happens.
Sending IS for a substitution to a retailer that does not permit substitutions, or AE where AC is required, gets the file rejected or the line escalated. This is guideline detail, not standard detail, and it is why pre built retailer maps beat a generic 855 template.
The acknowledgment is built from the live order rather than from a copy of it. When the 850 imports, AIMS360 validates each line against your product catalog and your available to sell position across your DC, your 3PL and your stores, then generates the 855 with the line statuses that reflect what you can actually commit.
The 855 fires on import, not on a clerk opening a queue, so a 24 hour window is met by process rather than by attention.
Pre built maps carry the status codes each account accepts, so you are not discovering a rejected code during certification.
The 855, the 856 and the 810 come off the same order, so what you acknowledged, shipped and billed reconcile by construction.
AIMS360 builds and processes the EDI in house and connects through whichever network your retailer mandates, with no per document or per kilocharacter charges of its own.
It is the purchase order acknowledgment a supplier sends back to a retailer after receiving an 850. It confirms the order was received and states, line by line, what will actually be shipped: accepted as ordered, accepted with a changed quantity or date, backordered, substituted or rejected. Most retailers measure fill rate against what you acknowledged rather than what they originally ordered, which makes the 855 a commercial document rather than a technical one.
The 997 functional acknowledgment confirms that a file arrived and was structurally valid. It says nothing about the content. The 855 is a business response: it says what you will ship. A retailer usually expects both, a 997 within a short technical window and an 855 within a longer business window. Sending a 997 and no 855 means the retailer knows their file arrived and still has no idea whether their order is being filled.
The 855 responds to the original purchase order. The 865 is the purchase order change acknowledgment or request, used when a change is in play: either you are acknowledging a retailer's 860 change, or you are proposing a change yourself. Same conversation, different point in it. Not every retailer uses an 865, and some handle changes by retransmitting the 850 instead.
Twenty four hours from receipt of the 850 is the most common requirement, used by Walmart, Target and Costco among others. Amazon vendor programs commonly allow 48 hours. The clock generally starts when the file lands on the retailer's side, not when someone in your business opens it, so any process that depends on a person checking a queue will eventually miss it. Always confirm the window in the guideline issued to your own account.
You can, and it is the single most expensive habit in retail EDI. Acknowledging a line you cannot ship sets the retailer's expectation at the full quantity and then fails it at the dock, which is worse for your scorecard than acknowledging the cut on day one. It also breaks the automated three way match between the acknowledgment, the ship notice and the invoice, which can hold payment. Acknowledge what you can actually commit.
They are line item status codes in the ACK segment. IA is item accepted as ordered. IQ is item accepted with a quantity change, which is how you communicate a cut. IB is item backordered. IR is item rejected. There are others, including IS for a substitution, DR for a rescheduled date and IP for price pending. Not every retailer accepts every code, so check which subset your account permits before you use one.
Not with AIMS360. The EDI is built into the ERP, so the 855 generates from the same order record that holds your inventory position, and connects through whichever network the retailer mandates. That matters more than it sounds: an 855 produced by a separate translator has to be told what you can ship, and whatever tells it is a second copy of the truth. Generating it from the live order removes that copy.
No. It is very widely required, including by Walmart, Target, Costco, Amazon and Kohl's, but some retailers publish an 855 mapping guide without listing it among the documents required from all vendors. Macy's and Bloomingdale's are an example. A document appearing in a retailer's guide library does not mean that retailer requires it from your account, which is worth checking before you build.
Last reviewed 7 August 2026 by the AIMS360 EDI team. Segment and code detail reflects the ANSI ASC X12 855 transaction set. Retailer timing windows and permitted code subsets come from each retailer's own EDI guidelines, are stated here as commonly required rather than universal, and can change without notice. Confirm against the guideline issued to your vendor account.
See AIMS360 generate the 855 from your own orders and inventory in a 30 minute demo.
