Services denied when authorization was requested
You asked for authorization before the service and the payer said no, and the service was done anyway.
CO = Contractual Obligation. The provider owes the difference. The patient cannot be billed for this amount. The same reason code can appear with a different group code; the group decides who may be billed.
Usual causes
- Authorization request denied for medical necessity and the service proceeded.
- A peer-to-peer review was offered but not done.
- The service was urgent and could not wait.
The fix
Appeal the authorization denial with the clinical records, the guideline the payer used and the physician's reasoning. For urgent care, document why it could not wait. Patient may be billed only if they signed a waiver knowing the service was denied.
Appeal or corrected claim?
Appeal, usually a clinical appeal with physician letter. A corrected claim will not help.
Deadline to watch
Appeal window per payer, commonly 60 to 180 days from the denial; Medicare Advantage: 65 days from the notice for a standard appeal.
Exact limits are in your payer contract or provider manual. When in doubt, send the correction or appeal this week.
CO-39 in short
What does CO-39 mean?
You asked for authorization before the service and the payer said no, and the service was done anyway. The official X12 text reads: "Services denied at the time authorization/pre-certification was requested."
What usually causes a CO-39 denial?
Authorization request denied for medical necessity and the service proceeded. A peer-to-peer review was offered but not done. The service was urgent and could not wait.
How do I fix CO-39?
Appeal the authorization denial with the clinical records, the guideline the payer used and the physician's reasoning. For urgent care, document why it could not wait. Patient may be billed only if they signed a waiver knowing the service was denied.
Should I appeal CO-39 or send a corrected claim?
Appeal. Appeal, usually a clinical appeal with physician letter. A corrected claim will not help.
What deadline applies to CO-39?
Appeal window per payer, commonly 60 to 180 days from the denial; Medicare Advantage: 65 days from the notice for a standard appeal.