CO-197 means the payer required a prior authorization, precertification or notification for this service and has none on record. If you did get one, add the number and resubmit. If not, ask whether the payer allows retro authorization. You generally cannot bill the patient.
The official wording
The X12 Claim Adjustment Reason Code list defines 197 as: "Precertification/authorization/notification/pre-treatment absent."
The letters in front are the group code. CO means contractual obligation (the provider absorbs it), PR means patient responsibility, and OA is other adjustment. The same reason code can come with different group codes, so always read both.
Common causes
- No authorization was requested.
- The authorization number was left off the claim.
- The authorization was under a different provider, location or code than the one billed.
- The plan changed and the new plan requires authorization when the old one did not.
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How to fix it
- Search for an existing authorization under the patient, provider and dates.
- If one exists, add the number and send a corrected claim.
- If not, ask the payer whether retro authorization is allowed, especially for urgent care.
- Appeal with records if the service was an emergency or the payer's own tool said no authorization was needed.
How to prevent it
- Check authorization rules at scheduling, using the exact CPT codes.
- Put the authorization number in the appointment and on the claim.
- Track authorization dates and units so services do not run past them.
One claim, start to finish
A patient gets an MRI of the knee on March 3. The payer requires prior authorization for advanced imaging. The front desk never requested it.
| Line on the remittance | Amount | What it means |
|---|---|---|
| Billed charge | $1,100.00 | Your charge for the MRI |
| CO-197 | $1,100.00 | No authorization on file. Provider absorbs it for now. |
| Paid by payer | $0.00 | Nothing paid until the authorization issue is fixed |
| Patient balance | $0.00 | You cannot move this to the patient |
If the authorization did exist and was just left off the claim, a corrected claim with the number gets this paid. If it never existed, your only routes are retro authorization or an appeal.
Remark codes that often come with CO-197
| Remark code | Official wording | What to do |
|---|---|---|
| M62 | "Missing/incomplete/invalid treatment authorization code." | The auth may exist. Find the number and send a corrected claim with it in box 23 (loop 2300, REF*G1). |
| N54 | "Claim information is inconsistent with pre-certified/authorized services." | An auth exists, but the claim does not match it. Compare CPT codes, dates, units, provider and place of service against the approval. |
Retro authorization: when to ask for it
Many payers will consider an authorization after the visit, but only in set cases and inside a short window. The common ones are:
- Emergency or urgent care where there was no time to call first.
- The patient's coverage was found late, such as a patient who said they were self-pay.
- The service changed during the visit, for example a planned X-ray became a CT.
Windows are short, often a few business days after the service. Check the payer's provider manual. If retro auth is refused, keep the refusal letter. You will need it for an appeal.
How to post CO-197
- Do not write it off on day one. Post the CO-197 as a denial and move the claim to a follow-up queue.
- Search your records and the payer portal for an approval that covers the date, code and provider.
- If found, send a corrected claim (frequency code 7) with the auth number.
- If not found, request retro auth or appeal with records within the payer's window.
- Write it off as a contractual adjustment only after every route is closed, and tag the reason so you can track front-desk misses.
CO-197 checklist
- ☐ The auth number is on the claim in box 23 or loop 2300 REF*G1.
- ☐ The CPT codes billed match the codes approved.
- ☐ The date of service falls inside the approval dates.
- ☐ The units billed do not go over the units approved. If they do, see CO-198.
- ☐ The rendering provider and location match the approval.
Questions people ask about CO-197
Can I bill the patient for CO-197?
Generally no for in-network services. Getting the authorization was the provider's responsibility.
What is the difference between CO-197 and CO-198?
CO-197 means no authorization was on file. CO-198 means there was one, but the service went beyond it, such as extra visits or units.
Where does the authorization number go on the claim?
On the CMS-1500, in box 23 (prior authorization number). On the electronic 837P, in loop 2300 with a REF segment using qualifier G1.
Can I get an authorization after the service?
Sometimes. This is called retro authorization. Many payers allow it for emergencies or when coverage was found late, inside a short window. Check the payer's provider manual before you assume it is allowed.
Should I appeal CO-197 or send a corrected claim?
Send a corrected claim if an authorization existed and was just missing from the claim. Appeal if no authorization existed but the service was an emergency or the payer's own tools said none was needed.
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All denial code guides
PR-1 · PR-2 · PR-3 · CO-4 · CO-5 · CO-11 · CO-15 · CO-16 · OA-18 · CO-22 · OA-23 · CO-24 · CO-26 · CO-27 · CO-29 · CO-31 · CO-45 · CO-49 · CO-50 · CO-59 · PR-96 · CO-97 · CO-109 · CO-119 · CO-129 · CO-140 · CO-146 · CO-151 · CO-167 · CO-170 · CO-181 · CO-185 · CO-197 · CO-198 · PR-204 · CO-234 · CO-236 · CO-242 · CO-252 · CO-253 · CO-288 · CO-A1 · CO-B7 · MA130 · N130 · N23 · N290
Timely filing limits by payer: Cigna timely filing limit · HealthSpring timely filing limit · Aetna timely filing limit · UnitedHealthcare timely filing limit · Humana timely filing limit · corrected claim timely filing limits
Sources: X12 Claim Adjustment Reason Code list (197), read October 27, 2026; CMS Medicare guidance where Medicare rules are mentioned; X12 Remittance Advice Remark Code list (M62, N54), read October 27, 2026; CMS-1500 claim form instructions (item 23). Last reviewed October 27, 2026. General information, not coding or legal advice. Payer rules differ, so check the remark code and the payer's own policy.