Denial Codes

CO-197 Denial Code: Precertification or Authorization Absent

What CO-197 means, how it differs from CO-198 and the retired code 15, and the exact path from denial to a paid claim: corrected claim, retro-auth or appeal.

The CO-197 denial code means the payer required a precertification, prior authorization, notification or pre-treatment approval for the service and found none on file. X12 defines reason code 197 as “Precertification/authorization/notification/ pre-treatment absent.” Whether you can still get paid depends on one question: did an approval exist that never reached the claim, or was it never requested?

This page walks through the official definition, the patient-balance rule, the remark codes, the usual causes, and the fix for each path. For the full list of codes, see the denial codes guide.

Updated 2026-10-23. Reviewed by Jacob Greenberg, ClaimCarePro.

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What does CO-197 mean? The official X12 definition

CO-197 combines the group code CO with Claim Adjustment Reason Code 197. On the X12 CARC list, read October 23, 2026, code 197 reads “Precertification/authorization/notification/pre-treatment absent.” It started October 31, 2006 and was last modified May 1, 2018 (x12.org).

The four words cover four different payer requirements: precertification (often for admissions and imaging), prior authorization (approval before a service), notification (a notice that a service happened, sometimes after the fact) and pre-treatment review. The code does not say which one was missed. The remark codes and the payer’s policy for that service do.

One common misreading: some sites define CO-197 as an authorization that is “valid but does not apply” to the service. That was the wording of reason code 15, which X12 deactivated on May 1, 2018. With 15 retired, a missing or mismatched authorization number is expressed with 197 or 198 plus a remark code such as M62 or N54.

CO-197 vs CO-198, 288 and other authorization codes

Authorization denials come under several reason codes. Read the number before you act:

Authorization-related reason codes and what each means
CARC	Official X12 text	What happened
197	“Precertification/authorization/notification/pre-treatment absent.”	No approval on file for a service that needed one.
198	“Precertification/notification/authorization/pre-treatment exceeded.”	Approval existed; the claim went past its visits, units or dates.
288	“Referral absent”	An HMO-style plan needed a referral from the primary care provider.
243	“Services not authorized by network/primary care providers.”	The network or PCP did not authorize the service.
15 (deactivated)	“The authorization number is missing, invalid, or does not apply to the billed services or provider.”	Stopped May 1, 2018. Auth-number problems now come back under 197 or 198 with a remark code.

What the CO group code means for the patient balance

CO means the adjustment falls under the provider’s contractual obligation, so a CO-197 amount is not a patient balance. X12 lists CO as Contractual Obligation and PR as Patient Responsibility; when a payer believes the patient should bear the cost of a missed authorization it uses PR instead, and you will see PR-197 on the remittance.

Most participation agreements put the job of obtaining authorization on the provider. That is why the denial lands on the practice, and why billing the patient without a contract basis can breach the agreement. If your contract allows a signed patient waiver for non-authorized services, the waiver has to exist before the service, not after the denial.

Remark codes (RARCs) that usually come with CO-197

X12 does not pair remark codes with reason codes; each payer picks them. These active RARCs from the X12 RARC list (read October 23, 2026) are the ones whose wording fits an authorization denial, and they decide which fix applies:

Remark codes that commonly accompany CO-197
RARC	Official X12 text	What it tells you
M62	“Missing/incomplete/invalid treatment authorization code.”	An auth may exist, but the number on the claim is missing or wrong.
N54	“Claim information is inconsistent with pre-certified/authorized services.”	The billed codes, dates, units, place or provider do not match the approval.
N130	“Consult plan benefit documents/guidelines for information about restrictions for this service.”	The plan’s policy requires something for this service; read it before appealing.
N517	“Resubmit a new claim with the requested information.”	The payer is inviting a corrected claim rather than an appeal.

Top causes of CO-197 denials

Common causes of CO-197 and the fix for each
Cause	What happened	Fix
No authorization requested	The service is on the plan’s prior-auth list and nobody checked.	Retro-auth if the payer allows it; otherwise appeal on medical necessity.
Auth obtained, number not on the claim	The approval lives in the payer portal but never reached the claim form.	Add the number and send a corrected claim.
Wrong code or provider on the auth	The approval names a different CPT code, rendering provider or location than the claim.	Ask the payer to amend the auth, then correct the claim.
Dates outside the approval	The visit happened before the start date or after the end date.	Request an amended date range or a new auth; appeal if the payer refuses.
Coverage changed	The patient switched plans, or a new primary payer has its own auth rules.	Get authorization from the plan that is actually primary.
Notification-only service not notified	Some plans need only a notice (for example, of an admission) within a set time.	Send the notice and ask for reprocessing; appeal if past the window.

How to fix a CO-197 denial

First, search for an existing authorization. Check the payer portal, the referral or auth log, faxed approval letters and the ordering provider’s office. Search by member, date range and code, because the approval may sit under the ordering physician rather than the rendering one.

Path A: the authorization existed

Match the approval to the claim: CPT/HCPCS code, units, dates, rendering provider, location.
Put the authorization number on the claim (item 23 on the CMS-1500, or the prior authorization reference in the electronic claim) and correct any mismatch.
Send a corrected claim the way the payer’s manual specifies. If the approval itself is wrong (wrong code, wrong provider), ask the payer to amend it first.

Path B: no authorization was obtained

Check whether the payer accepts retro-authorization for this service and situation. Payers publish these rules in their provider manuals, and they usually depend on why the auth was missed: an emergency, coverage the patient did not disclose, or a plan change. Windows vary by payer and plan type, so read the current manual and note the section you relied on.
If retro-auth is allowed, submit it with the clinical notes, then rebill with the new number.
If it is not, appeal on medical necessity: the visit notes, the reason the service could not wait (if true), the order, and the payer’s own coverage policy showing the patient met its criteria. Appeal inside the payer’s appeal window and keep the proof of submission.
If the payer upholds the denial and your contract bars billing the patient, write it off as a contractual adjustment and record why, so the cause gets fixed upstream.

For Medicare Advantage, Medicaid and Exchange plans, CMS rule CMS-0057-F requires a specific reason for any denied prior-authorization request beginning in 2026. Use that reason in your appeal: it tells you exactly which criterion to address.

Prior authorization rules worth knowing

Original Medicare requires prior authorization as a condition of payment for certain hospital outpatient department services: blepharoplasty, botulinum toxin injections, panniculectomy, rhinoplasty and vein ablation (from July 1, 2020), implanted spinal neurostimulators and cervical fusion with disc removal (from July 1, 2021), and facet joint interventions (from July 1, 2023), per CMS. CMS removed CPT 64492 and 64495 from that list in August 2024.
Medicare Advantage, Medicaid, CHIP and Federally Facilitated Exchange plans must decide expedited requests within 72 hours and standard requests within seven calendar days, generally beginning January 1, 2026 (CMS-0057-F). Drug prior authorizations are excluded from the denial-reason requirement.
Commercial plans publish their own lists, often by specialty (imaging, cardiology, oncology, therapy). Lists change during the year; check the payer’s current list for each code, not last year’s.

How to prevent CO-197 denials

Check the payer’s prior-auth list for every scheduled code, at scheduling, not at check-in.
Re-verify when coverage changes. A new primary payer, found through a CO-22 coordination-of-benefits denial, brings its own authorization rules.
Store the auth number, codes, units and date range where the claim is built, so it prints on the claim.
Track remaining visits or units on each approval and request extensions before they run out.
Confirm the approval names the rendering provider and location who will actually see the patient.

A missing number on an otherwise clean claim can also come back as CO-16 (claim lacks information); the remark code tells you which.

When to hand authorization denials to someone else

Authorization denials are deadline work: a retro-auth window, an appeal window and timely filing all run at once. ClaimCarePro’s denial management service triages every denial by reason and remark code, checks for an existing approval first, requests retro-auth or appeals with the clinical record, and reports to the practice every week. Our team brings 30+ years of combined billing experience.

CO-197 questions, answered

What does denial code CO-197 mean?

CO-197 means the payer required a precertification, authorization, notification or pre-treatment approval for the service and found none. X12 defines reason code 197 as “Precertification/authorization/notification/pre-treatment absent.” The CO group code makes it a contractual adjustment, not a patient balance.

Can I bill the patient for a CO-197 denial?

Generally not when you are in network. CO is the Contractual Obligation group, and most participation agreements make the provider responsible for obtaining required authorizations. Some payers allow billing the patient only if the patient signed a specific financial waiver before the service; check the contract before sending any statement.

Can I get a retro authorization for CO-197?

Sometimes. Many payers accept a retroactive authorization request for urgent or emergency care, or when the patient’s coverage was not known at the time of service, but the rules and windows are set by each payer’s provider manual. Read your payer’s current manual before requesting one; we do not publish day counts we have not verified.

What if the authorization existed but the claim still denied CO-197?

Then the claim usually did not carry the authorization number, carried the wrong one, or the services did not match what was approved. Put the correct number on the claim (box 23 on a CMS-1500 or its electronic equivalent), confirm the codes, dates and provider match the approval, and send a corrected claim.

What is the difference between CO-197 and CO-198?

CO-197 means no authorization was on file. CO-198, “Precertification/notification/authorization/pre-treatment exceeded,” means one existed but the claim went past it: more visits or units than approved, or dates outside the approved window. The fix for 198 is usually an extension request or appeal, not a new authorization.

Which remark codes come with CO-197?

Payers choose the remark codes. Ones whose X12 wording fits include M62 (“Missing/incomplete/invalid treatment authorization code”), N54 (“Claim information is inconsistent with pre-certified/authorized services”) and N130 (consult plan benefit documents for restrictions on the service).

Does Medicare require prior authorization?

Original Medicare requires it for a limited list, including certain hospital outpatient department services such as blepharoplasty, botulinum toxin injections, panniculectomy, rhinoplasty, vein ablation, implanted spinal neurostimulators, cervical fusion with disc removal and facet joint interventions. Medicare Advantage plans set their own lists and require it far more often.

How fast must a payer decide a prior authorization request?

Under CMS rule CMS-0057-F, Medicare Advantage plans, Medicaid and CHIP programs and plans, and Federally Facilitated Exchange plans must decide expedited requests within 72 hours and standard requests within seven calendar days, generally beginning January 1, 2026, and give a specific reason when they deny.

Denied and aged A/R is worked on a 10% contingency of what is recovered: no recovery, no fee. Ongoing billing is 6% of collections with a $1,000 monthly minimum, denial work included. Details on the pricing page.

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Updated 2026-10-23. Reviewed by Jacob Greenberg, ClaimCarePro.

Sources

X12 Claim Adjustment Reason Codes, read October 23, 2026
X12 Remittance Advice Remark Codes, read October 23, 2026
CMS fact sheet: Interoperability and Prior Authorization Final Rule (CMS-0057-F), read October 23, 2026
CMS: Prior Authorization for Certain Hospital Outpatient Department Services, read October 23, 2026