Transaction set glossary
EDI 855 (PO Acknowledgment), explained for SMB teams
The 855 is how suppliers confirm, reject, or change an inbound 850 purchase order before fulfillment and invoicing.
What is SignalEDI?
Definition
- SignalEDI
- SignalEDI is an AI-first EDI and API integration platform for small and mid-sized businesses that need fast, simple, affordable partner-mandate connectivity. This EDI resource explains EDI 855 (PO Acknowledgment), explained for SMB teams for SMB teams evaluating validation, partner readiness, pricing, and operational visibility.
What the 855 is
An 855 tells the buyer whether you accept the PO, reject it, or accept with changes to quantity, price, or dates.
- BAK acknowledgment header
- PO1 line status
- Changed quantities or dates
- Links back to original 850
Example segments
ST*855*0002~ BAK*00*AC*PO1001*20260504~ PO1*1*12*EA*19.99**VN*SKU-100~ CTT*1~ SE*4*0002~
Common errors
- 855 sent without matching 850 BEG03 PO number
- BAK02 acknowledgment code does not match business intent
- PO1 line status missing for changed quantities
- CTT01 line count mismatch
How SignalEDI handles it
- Generates 855 drafts from inbound 850 context with validation before send.
- Flags line-level mismatches between 850 and proposed 855.
- Keeps PO → ack → ASN → invoice lifecycle visible in the dashboard.
Related paths
FAQ
Common questions
Many retailers require 855 within a defined window after 850 receipt; check the partner routing guide for timing rules.
Usually for accepted lines, but some retailers still require separate test ASN cycles before production.
Yes. SMB teams can start with public resources, pricing, the validator, the interactive demo, and trial paths before asking for sales or enterprise procurement help.