Reference·AK9 Segment·AK9*A
X12 999 Reference

What Is X12 999 AK9*A? Accepted, Explained for Testers

Jul 27, 2026 · 4 min read
← AK901 AK9*R →

Seeing AK901 equal to A feels like the end of the story, which is exactly why the counts sitting right after it get skipped — and an accepted group with a count mismatch is still a group that lost data somewhere in transit.

Quick answer

AK9*A is the AK9 segment with acknowledge code A, meaning the receiver validated and accepted every transaction set in the functional group with no rejections.

What this element contains

A
Accepted — the group as a whole cleared validation with nothing rejected
Expected pairing
AK902 = AK903 = AK904 — a clean acceptance should show the included, received, and accepted counts all matching
Distinct from
E (Accepted, But Errors Were Noted) — A implies no flagged issues at all, not merely no rejections

Example

Synthetic example Generated by Synthibase 
AK9*A*1*1*1

A synthetic fully accepted functional group — one transaction set included, received, and accepted, with no discrepancy between the counts. Synthetic test data.

Where this trips people up

It is possible to receive AK901 = A while AK902 and AK903 do not match, if the trading partner's translator only checks the sets it actually received rather than reconciling against what the sender intended to send. Automation that treats "A" as a green light to close out the batch without also diffing the counts can mark a functional group complete when a transaction set silently never arrived.

→
X12 999 AK9 Segment Guide: Fields, Format, and Testing Gotchas
 →
How to Validate X12 EDI Files Before Payer Submission
 →
X12 GS and ST Segments Explained: Functional Group and Transaction Headers
Don't let a clean AK901 hide a count mismatch
Synthibase generates synthetic 999 acknowledgments where AK901 is A but the transaction-set counts intentionally diverge, so reconciliation logic gets tested against the scenario a passing acknowledge code alone will never reveal.
Start free trial →
This page is written independently by Synthibase for testing and informational purposes. It is not an official publication of HL7 International or X12/Washington Publishing Company, and is not a substitute for reviewing the official standard or your trading partner's companion guide. See our Terms of Service for full legal terms.