Denial code CO-197
CO-197 Denial: Prior Authorization Missing or Not Obtained
CO-197 means the payer required authorization before the service and did not have one on file. In dermatology it attaches overwhelmingly to biologics, to phototherapy courses, to some laser and surgical procedures, and increasingly to advanced imaging and pathology sent to particular labs. It is the most preventable denial on this list and the least recoverable after the fact, which is a bad combination for a practice that treats it as a billing problem.
CO-197 is one of the codes covered in our dermatology denial codes index, which explains what each remittance code means and what actually clears it.
What the payer is saying
Precertification, authorization, notification or pre-treatment requirement was not fulfilled.
Why it is so hard to fix after the service
Most payer contracts state that authorization must be obtained before the service, and most will not backdate one. Retroactive review is sometimes available for genuinely urgent care or for retroactive eligibility, and those are narrow exceptions with their own filing deadlines. Outside them, the practice is arguing for an exception rather than appealing a decision.
For a buy-and-bill biologic the exposure is worse than the professional fee, because the practice has already paid acquisition cost on a drug that has already been administered. A single missed authorization on a high-cost agent can exceed a month of professional collections.
The workflow that prevents it
- Authorization requirements checked at scheduling, against the specific plan rather than the payer name — requirements differ sharply between a payer's commercial, exchange and Medicare Advantage products.
- Benefit verification repeated close to the date of service, since plan changes and terminations are the second most common cause after the requirement simply being missed.
- Authorization numbers, approved units and valid date ranges stored where the biller sees them at claim build, not in a fax folder.
- Expiry tracked for treatment courses. A phototherapy authorization covering a fixed number of sessions across a fixed window will silently run out mid-course.
- A stop rule: high-cost drugs are not administered without confirmed authorization on file, with an explicit clinical override path so the decision is made by a person rather than by omission.
When you do have to appeal it
Where an authorization existed but the claim was denied anyway, this is usually a mismatch rather than an absence: the code billed differs from the code authorized, the units exceed those approved, the rendering provider differs from the one on the authorization, or the date falls outside the approved range. Those are corrected claims, not appeals, and they resolve quickly once the mismatch is identified.
Where no authorization existed, the argument has to be an exception — urgency, retroactive eligibility, or a documented payer representative's statement that none was required. That last one is why calls to payers need reference numbers and representative names recorded at the time, because it is the only evidence that argument ever has.
What creates CO-197 in the first place
This denial is produced upstream, in the way the procedure is coded or the modifier is applied. These are the pages that cover the cause.
Frequently asked questions
Can the patient be billed for a service denied as CO-197?
Usually not. Most contracts make an authorization failure a provider write-off rather than patient responsibility, and billing the patient anyway can breach the contract.
Does a referral count as an authorization?
No. They are separate requirements and some plans need both. A valid referral on file does not prevent a CO-197 on a service that also required precertification.
Other denial codes in the index
Have us work your CO-197 volume
Appeals recover last month's money; the pattern behind CO-197 decides next month's. Our denial team works the queue and fixes the upstream rule that keeps producing it.