CO-197 Denial Code: Missing Prior Authorization in Behavioral Health
CO-197 is the denial behind many of behavioral health's largest write-offs, because the services that need authorization are the expensive ones: IOP, PHP, residential, psychological testing, and many Medicaid services. Some are recoverable. Most are preventable.
Short answer
CO-197 combines group code CO (the provider can't bill the patient) with reason code 197: "Precertification/authorization/notification/pre-treatment absent." The payer found no authorization for the service, date, or provider billed. Check whether an authorization exists and was left off the claim; if not, ask whether the payer allows retro-authorization, and appeal only when you had one or the care was an emergency.
Where behavioral health claims hit CO-197
- Higher levels of care. IOP, PHP, and residential almost always need authorization, and concurrent review to continue. See IOP and PHP billing.
- Psychological and neuropsychological testing. Many plans authorize testing hours in advance and deny hours beyond the approval.
- Medicaid managed care services. Community services billed with H codes often need a service authorization from the plan.
- Outpatient visits past a limit. Some plans authorize a block of therapy sessions; session 13 of 12 denies.
- The authorization doesn't match. It exists, but for another code, date range, level of care, or clinician. Remark N54 often signals this.
How to fix CO-197
| Situation | What to do |
|---|---|
| The authorization exists but wasn't on the claim | Add the authorization number (loop 2300 REF*G1 on an 837P, box 23 on a CMS-1500) and send a corrected claim. |
| It exists but for a different code, provider, or dates | Ask the payer to update the authorization, then resubmit. Some will, within a window. |
| No authorization, but the payer allows retro-authorization | Request it with the clinical record and the reason it wasn't obtained in advance. |
| Emergency or crisis admission | Appeal with the documentation of the emergency and any notification you made. |
| No authorization and no exception | Write it off. CO means the patient can't be billed. |
How to stop seeing it
- Check authorization at intake, alongside eligibility and benefits, for every payer and service.
- Track units and end dates, not just approval, so sessions past the count or after the end date are caught before they're delivered.
- Start concurrent review early for IOP and PHP, before the current authorization runs out.
- Re-check on plan changes. A Medicaid member moving between plans needs a new authorization from the new plan.
More: prior authorization in behavioral health and all behavioral health denial codes.
Code wording from the X12 Claim Adjustment Reason Code and Remittance Advice Remark Code lists, read October 19, 2026. X12 updates the lists several times a year, and each payer decides which codes it sends for which problem, so read the remark codes on your own remittance.
Frequently asked questions
What does denial code CO-197 mean?
Precertification, authorization, notification, or pre-treatment was absent. The payer had no authorization matching the service, date, and provider, and the provider can't bill the patient.
Can a CO-197 denial be appealed?
Yes, when you had an authorization that the payer didn't match, or when the service was an emergency. Without an authorization, ask whether the payer allows retro-authorization.
Where does the authorization number go on a claim?
In box 23 of the CMS-1500, or in a REF segment with qualifier G1 in loop 2300 of the 837P.
Which behavioral health services usually need prior authorization?
IOP, PHP, residential treatment, psychological and neuropsychological testing, and many Medicaid community services. Some plans also cap outpatient therapy sessions.
Authorizations tracked to the last unit.
Stable tracks every authorization's units and end date and flags sessions that would exceed it before they're delivered.
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