AK5-M | Rejected (MAC Failed)

Industry

Insurance

Canonical

/insurance/claims-processing/error-codes/ak5-m/

Last Updated

Apr 16, 2026

Summary

AK5-M means the 997 transaction set was rejected because the message authentication code (MAC) failed.

Learn More

Use these links to pivot between the directory, a focused guide, and nearby related codes.

Hub

Insurance
Claims Processing

Guides

Insurance Claims Processing Errors: Causes, Codes & Solutions
EDI 837 & 835 Errors in Insurance: Complete Troubleshooting Guide

Related Codes

AK9-M — Group Rejected (MAC Failed)
AK5-W — Rejected (Assurance Failed)
AK5-X — Rejected (Decryption Content Unreadable)
AK5-A — Transaction Set Accepted
AK5-R — Transaction Set Rejected

What This Code Means

AK5 “M” is a rejection condition tied to message authentication. In practical payer/clearinghouse workflows, this usually points to transport/security configuration problems rather than claim content.

Step-by-step fix

1) Confirm you are using the correct secure transport method required by the trading partner (SFTP/AS2/VPN, certificates, keys).

2) Check certificate validity dates and whether the partner rotated keys/certs.

Related Codes

8 links

AK9-M Code

Group Rejected (MAC Failed)
AK5-W Code

Rejected (Assurance Failed)
AK5-X Code

Rejected (Decryption Content Unreadable)
AK5-A Code

Transaction Set Accepted
AK5-R Code

Transaction Set Rejected
AK9-P Code

Partially Accepted
AK9-W Code

Group Rejected (Assurance Failed)
AK9-X Code

Group Rejected (Decryption Content Unreadable)