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Claim adjustment reason code

CO-197: Prior authorization absent

CO-197 means: Precertification/authorization/notification/pre-treatment absent. The payer required prior authorization for this service and cannot find one attached to the claim.

Read the group code before you act on this

197 is the claim adjustment reason code. The CO in front of it is the group code — a separate field the payer sets on the remittance. The same reason code arrives under different group codes depending on the payer and the situation, and the group code, not the reason code, decides who owes the money.

CO — contractual obligation. You write it off. You may not bill the patient.
PR — patient responsibility. Billable to the patient.
OA — other adjustment, and PI — payer initiated reduction. Neither is patient responsibility.

What causes it

Authorization was never obtained because nobody checked whether the code required one
Authorization was obtained but the number was not put on the claim
The authorization covered a different CPT code than the one performed
The service went beyond the number of units or visits the authorization allowed
The authorization expired before the date of service
The rendering provider on the claim is not the one named on the authorization

How to work it

Pull the authorization record and compare four things against the claim: the CPT code, the units, the date range and the rendering provider
If a valid authorization exists and simply was not transmitted, correct the claim and resubmit rather than appealing
If the authorization covers a different code, check whether the payer allows a retro-authorization and how many days you have — the window is often as short as 72 hours after service
If it was genuinely never obtained, file a retro-authorization request with the clinical documentation showing medical necessity, and expect to lose some of these
Log the reference number and the name of the person who confirmed it, every time

How to stop it recurring

This denial is almost entirely preventable, and in our experience it is one of the most common reasons a clean chart goes unpaid. The fix is a person who checks the authorization requirement before the visit rather than a person who discovers it afterwards.

Who does this work

A prior authorization seat at $1,900 per seat per month works this queue full time, during your business hours, inside your own system. Every call is logged with the payer reference number and the outcome, and every Friday you get it in writing.

What that seat does →

Codes worked the same way

CO-197 is taken back to the authorization. So are these, which is why a queue sorted by recovery route moves faster than one sorted by code number — the same person, in the same system, with the same evidence to hand, clears all of them in one pass.

CO-15 — Authorization number missing
CO-39 — Authorization already refused
CO-272 — Coverage guidelines not met
N54 — Claim does not match the authorization

Specialties that name this among their costliest

These are specialties whose own worst denials include one of this kind. The line under each is the denial they name, quoted from their page so you can see what the link is based on.

Ambulatory Surgery Centers
Prior authorization obtained for the surgeon but not the facility
Behavioral Health
Authorization units exhausted mid-course without renewal
Urology
Prior authorization missing for advanced imaging
Radiology
Advanced imaging denied for missing prior authorization
Ophthalmology
An injection given after the drug authorization lapsed, or under an authorization written for a different agent than the one actually drawn up that day.
Neurology
Long-term video EEG authorized as an ambulatory home recording but performed as an admission to the epilepsy monitoring unit, so the facility days sit outside the authorization

What leaving it costs

Working a denied claim costs $57.23 per denied claim in administrative time. Source. At 100 denials a month — an illustration, not a measurement of your practice — that is $5,723 a month, or $68,676 a year, in labour alone.

The figure that makes it worth spending: about 90% of initially denied claims are eventually paid. Source. The reason a denial sits is almost never that nobody knows how to work it — it is that nobody has the hours.

Questions

What does denial code CO-197 mean?

Precertification/authorization/notification/pre-treatment absent. In plain terms: The payer required prior authorization for this service and cannot find one attached to the claim.

What causes CO-197?

Authorization was never obtained because nobody checked whether the code required one. Authorization was obtained but the number was not put on the claim. The authorization covered a different CPT code than the one performed. The service went beyond the number of units or visits the authorization allowed. The authorization expired before the date of service. The rendering provider on the claim is not the one named on the authorization.

How do you fix a CO-197 denial?

Pull the authorization record and compare four things against the claim: the CPT code, the units, the date range and the rendering provider. If a valid authorization exists and simply was not transmitted, correct the claim and resubmit rather than appealing. If the authorization covers a different code, check whether the payer allows a retro-authorization and how many days you have — the window is often as short as 72 hours after service. If it was genuinely never obtained, file a retro-authorization request with the clinical documentation showing medical necessity, and expect to lose some of these. Log the reference number and the name of the person who confirmed it, every time.

Can CO-197 be prevented?

Is CO-197 the same as PR-197?

Same reason, different group code. The number 197 is the reason: The payer required prior authorization for this service and cannot find one attached to the claim. The prefix says who carries the amount. CO means contractual obligation — the payer says the amount is not billable to anybody, and it is written off unless the denial itself is overturned. PR-197 is the same reason assigned to patient responsibility — the payer says the amount is owed by the patient, and it is billed to them. Read the prefix before the number: it decides whether you appeal, write off, or bill the patient.

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

CO-197: The payer required prior authorization for this service and cannot find one attached to the claim. CO-198: An authorization exists. The problem is that you went past what it allowed — more units, more visits, or a longer date range than was approved. They are different reasons that happen to sit next to each other in the list, and they are worked differently — CO-197 is taken back to the authorization; CO-198 is answered with the document the payer names.

Code descriptions are the standard X12 claim adjustment reason and remittance advice remark code text. Payer policies differ, and the payer’s own coverage policy governs any individual claim. This page is working guidance, not legal or clinical advice.

Last updated 2026-09-12. This is operational guidance drawn from payer remittance practice, not legal, coding or reimbursement advice. Payer-specific rules vary and change; confirm against the payer’s own policy before acting on a specific claim.

Written by Ibtesam Asif · Last reviewed 2026-09-12

Code descriptions are the standard published text. Everything after them is operational guidance from our own work, and payer policy governs any individual claim.

Other denial codes

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