CO-197 Denial Code: Prior Authorization Absent

What CO-197 means

CARC 197 reads “Precertification/authorization/notification/pre-treatment absent.” The payer requires advance approval or notice for this service, and when it adjudicated the claim, it found none. The term covers several flavors of the same requirement: prior authorization for procedures and imaging, precertification for admissions, notification of inpatient stays, and pre-treatment review for dental and some therapy services.

CO-197 is one of the most consequential preventable denials, because it often involves high-cost services and many payers don’t allow authorizations after the fact.

Example: an outpatient MRI is performed on the date it’s ordered. The payer requires prior authorization for advanced imaging, but none was requested. The claim is denied CO-197. The payer doesn’t offer retro-authorization for non-urgent imaging, so the amount is written off.

Common causes

• No authorization requested because staff didn’t know the service required one.
• Authorization requested but not approved before the service, or still pending.
• Authorization number missing from the claim (box 23 or the 837 REF segment), so the payer couldn’t link it.
• Approval issued to a different provider, NPI, or location than the one billing.
• Service changed during the visit, such as a different or additional procedure than what was approved.
• Plan changed (new payer or new plan year) and the authorization from the old plan doesn’t carry over.
• Admission notification not given within the payer’s window.

How to fix it

1. Search your records for any authorization or reference number, including call logs and portal submissions.
2. If an authorization exists, confirm it matches the provider, service codes, dates, and location, then add it to box 23 and submit a corrected claim (resubmission code 7 in box 22 with the original claim number) or ask the payer to attach it.
3. If none exists, ask whether the payer accepts retro-authorization requests and within what window. Submit clinical documentation promptly.
4. Appeal when the service was emergent, eligibility was unknown at the time of service, the authorization was requested but not acted on, or the service didn’t actually require authorization under the payer’s list.
5. If nothing applies, write off the CO amount. Do not transfer it to the patient.

How to prevent it

• Check authorization requirements at scheduling using each payer’s current list, which often changes annually or quarterly.
• Track authorizations in one place with number, dates, units, provider, and location, and attach them to claims automatically.
• Re-verify eligibility and plan before the service, since a plan change can void an existing authorization.
• Build a hard stop in scheduling for services on authorization lists without an approval on file.
• Include the authorization number on every claim that needs it. The Claims Validator can flag services that commonly require authorization when box 23 is blank.
• Learn more in prior authorization and referral denials and preventable denials.

Specialty notes

Behavioral health (intensive outpatient, partial hospitalization, psychological testing, and some psychotherapy under certain plans), PT/OT (visits after an initial allowance), DME, and advanced imaging are among the services most commonly subject to authorization. Requirements vary widely by payer and plan.