What CO-50 means
The payer decided the service was not medically necessary for the diagnosis given.
The CO group code means this amount is a contractual obligation: under most contracts you cannot bill it to the patient.
Common causes
- Diagnosis does not support the service under payer policy
- Missing documentation of necessity
- No ABN for Medicare patients
How to fix it
- Check the diagnosis against the payer's coverage policy (LCD/NCD for Medicare)
- Appeal with medical records if the service was necessary
- Use ABNs when coverage is doubtful
Check the remark code (RARC) that came with the denial and the payer's own policy, since rules vary by payer and plan. This is a plain-English summary written by GetMax; the official code text is published by X12 at x12.org/codes.
Prevent it next time
Most denials are caused before the claim is sent. See 12 ways to reduce claim denials, or let our denial management team work them for you.