CO-197 Denial Code: Precertification Absent, How to Appeal and Prevent

By Dr. Zain Vally | Updated November 2026 | Medical Billing Denials

A CO-197 denial means the payer looked for a precertification, authorization or notification tied to the billed service and found none it could match. The denial says nothing about whether the service was medically necessary or correctly coded. It says the payer's authorization record and the claim do not line up.

The "CO" group code assigns the amount to the provider as a contractual obligation, so the balance cannot be moved to the patient. Recovery runs through one of two doors: get an authorization on file that matches the claim, or appeal with records that show why the service should be paid anyway.

The Official CARC 197 Description

CARC 197: "Precertification/authorization/notification/pre-treatment absent."

Source: X12 Claim Adjustment Reason Code list. Start date 10/31/2006, last modified 05/01/2018.

Its four terms cover four different payer requirements. Precertification and authorization are approvals obtained before the service. Notification is a report to the payer, often after an admission, and pre-treatment applies mostly to dental plans.

CO-197 vs. CO-15 vs. CO-198

Three reason codes describe authorization problems, and each one sends the billing team to a different fix. The descriptions below are quoted from the X12 code list.

Code	Official description	What it points to
CO-197	Precertification/authorization/notification/pre-treatment absent.	The payer has no authorization it can match to this service, date, provider or site.
CO-15	The authorization number is missing, invalid, or does not apply to the billed services or provider.	An authorization exists, but the number on the claim is wrong or absent. X12 retired this code on 05/01/2018, so it should only appear on older remits.
CO-198	Precertification/notification/authorization/pre-treatment exceeded.	An authorization matched, but the visits, units or dates it approved have run out.

Because CARC 15 is retired, a wrong or missing authorization number on a current remit usually arrives under another reason code. The remark code (RARC) on the same line is the place to look for the specific problem.

Five Situations That Produce CO-197

Nobody obtained the authorization. Someone assumed the service did not need one, or the request was started and never finished. The payer's prior authorization list for that plan settles the question.

The approval covers the wrong CPT code or date range. An approval for CPT 78451 (single-study SPECT myocardial perfusion imaging) does not cover a claim billed as 78452 (multiple studies). A date of service outside the approved window fails the match the same way.

An approval exists under the wrong NPI or location. When a payer ties the approval to the requesting provider or servicing site, a claim from a different NPI finds nothing to match. Multi-location groups hit this one most.

A notification rule was missed. Some services need no advance approval but do require the payer to be told within a set time, commonly after an admission. The window comes from the plan's provider manual, and a late or missing notice draws the same denial.

An approval expired before the date of service. Each approval carries a validity period set by the payer. A procedure rescheduled past that date is billed against an authorization that no longer exists.

Retro-Authorization Windows by Payer

A retrospective authorization asks the payer to approve a service after it was performed. The table lists only payers whose published policy states a rule, with the source named.

Payer and product	Published rule	Source
Aetna Better Health of Kentucky (Medicaid)	"A provider has seven (7) days from the date the service was performed to submit a retro authorization request," for a medically necessary service performed without authorization.	Aetna Better Health of Kentucky, Prior Authorization Guidance
Priority Health (commercial, Medicare and Medicaid)	No day count stated. Retro requests "will only be considered in limited, exception-based situations," such as urgent care, coverage that could not be identified at the time of service, or an administrative error.	Priority Health provider manual, Retrospective authorizations
UnitedHealthcare, Aetna commercial, Cigna, BCBS plans	No general retro window found in published material. The window is set by the provider contract and the plan's provider manual.	Your contract; the plan's provider manual

Even a seven-day window like Aetna Better Health of Kentucky's usually closes before the denial arrives. The retro request has to start when the miss is discovered at the front desk or in charge review, not when the remit posts.

The Appeal Packet

A CO-197 appeal answers two questions: what happened to the authorization, and why the service should be paid regardless. Four pieces of evidence carry it.

Authorization request records

Portal submission screens, fax confirmations, call reference numbers and any approval letter. An approval issued under a different NPI or CPT turns "no auth" into "auth mismatch," which is a much easier case to make.

Clinical notes

Include the ordering note, the indication and the relevant prior results. If the payer's own clinical policy covers the indication, cite the policy number and the criteria met.

The payer's own policy page

A copy of the prior authorization list or notification rule in effect on the date of service. This matters most when a code was added to the list recently or the rule changed mid-year.

Proof of the eligibility check

The eligibility response for the date of service. It shows the plan on file was the plan billed and keeps an eligibility objection from being added during review.

File inside the appeal window printed on the denial or set by the contract. For traditional Medicare, a redetermination request is due within 120 days of receiving the initial determination (42 CFR 405.942).

Illustrative Example: A Stress Test Done at the Other Location

A four-location cardiology group orders a nuclear stress test, CPT 78452, for a commercially insured patient. Location A's scheduler requests the authorization under Location A's NPI, and the payer approves it. When the camera there goes down for service, the patient is moved to Location B the week of the test.

Denial. The claim goes out under Location B's NPI. On the payer's side sits an approval for the right patient, code and dates, tied to Location A, and the remit comes back CO-197.

Recovery. The billing team asks the payer or its imaging benefit manager to update the servicing provider on the existing approval, then sends a corrected claim with the same authorization number. A refusal moves the case to appeal, with the Location A approval letter and the reschedule record at the front of the packet.

What it shows. Nothing about the patient, the code or the medical need changed. Only the site moved, and the authorization stayed behind.

Prevention, and Why Multi-Location Groups See More CO-197

A single site has one NPI, one scheduling desk and one person who knows which tests need approval. Each added location adds a place where an approval can be requested under one NPI and performed under another. It also adds a desk that can assume another desk already handled it.

Check authorization at scheduling. Build alerts in the practice management system for every CPT on your top payers' prior authorization lists, so the approval number is attached to the appointment before the patient arrives.
Run one authorization queue for all sites. Approvals tracked in separate spreadsheets per location are where cross-site moves get lost. A shared queue shows what is approved, pending or about to expire everywhere at once.
Add an authorization step to every reschedule. A change of site, date or code triggers a check of the existing approval and a call to update it when it no longer matches.
Report expirations weekly. A list of approvals expiring in the next 14 days gives staff time to extend them before the test date passes the window.
Keep a list of delegated vendors. Many plans route imaging approvals to a benefit manager, and a call to the wrong party finds no record. Post which plans delegate, and to whom, where the scheduling team can see it.

We run these checks for multi-location group practices as part of the location-level reporting we deliver weekly. The reschedule step is the one that covers the stress test example above.

Related Denial Codes

CO-15: "The authorization number is missing, invalid, or does not apply to the billed services or provider." Retired by X12 on 05/01/2018 and may still appear on older remits.
CO-198: "Precertification/notification/authorization/pre-treatment exceeded." The approval matched, but its visits, units or dates were used up.
CO-50: "These are non-covered services because this is not deemed a 'medical necessity' by the payer." A CO-197 appeal that reaches clinical review can come back under this code.
CO-4: "The procedure code is inconsistent with the modifier used." A code or modifier changed after the approval was issued can draw CO-4 and CO-197 on the same claim.

Running authorizations across several locations?

We track approvals, reschedules and denials by site for group practices.

See How We Work With Group Practices

Frequently Asked Questions

What does CO-197 mean on a remittance?

CARC 197 reads "Precertification/authorization/notification/pre-treatment absent." The payer found no authorization it could match to the billed service. The CO group code makes the amount a contractual adjustment owed by the provider.

Can a CO-197 balance be billed to the patient?

No. The CO group code places the amount on the provider under the payer contract. Recovery comes from a retro authorization, a corrected claim or an appeal.

How is CO-197 different from CO-198?

CO-197 means no matching authorization was found. CO-198 means an authorization matched but the visits, units or dates it approved were exceeded. CO-15, the old code for a wrong authorization number, was retired by X12 in 2018.

Is there a deadline for a retro authorization?

It depends on the payer, and many do not publish one. Aetna Better Health of Kentucky allows seven days from the date of service, while Priority Health considers retro requests only in listed exceptions. For other payers the window is set by the contract and the plan's provider manual.

Why do multi-location groups see more CO-197 denials?

An approval requested under one location's NPI may not match a claim from another location. Patients moved between sites for scheduling or equipment reasons carry that risk on every visit. A reschedule step that checks and updates the approval prevents it.

Looking up another code? Browse the full Denial Code Reference.