Denial code · CARC 39
CARC 39 (CO-39): service denied when authorization was requested
What CO-39 means, why the real dispute is the earlier prior-authorization decision, and how to appeal it for residential, PHP, TMS and ABA services.
By the ClaimParrot editorial team · Who we are · Reviewed · 4 min read · 7 cited sources
Quick answer
CARC 39 means the plan refused the service when someone asked for prior approval, and the claim is denied for the same reason. The claim denial is an echo: the real dispute is the earlier authorization decision, usually a medical-necessity call. Appeal that decision with records and the criteria; correcting the claim will not help.
| Item | Detail |
|---|---|
| Code | CARC 39 · Active on the X12 list; checked October 14, 2026 |
| Plain meaning | Someone asked the plan for prior approval, the plan said no, and the claim for that same service is denied because of that earlier decision. |
| Group codes seen | CO (contractual obligation), PR (patient responsibility) |
| Common remark codes | N758, N10, N939, N54 |
| Where it shows up in BH | Residential mental health, Partial hospitalization (PHP), TMS, ABA therapy |
| Usual next step | Appeal the original authorization decision |
| Related codes | CARC 197, CARC 50, CARC 198 |
What does CARC 39 mean?
CARC 39 tells you a pre-service decision already exists and it was a no. Unlike 197, the plan knows about the service; unlike 50, the judgment was made before care began. Treat the claim as a pointer back to the authorization file, where the reasons and the appeal clock live.
What do CO-39 and PR-39 mean for who pays?
CO-39 leaves the amount with the provider, which delivered care after a refusal. PR-39 means the plan treats the member as responsible, which is only fair to bill if the member knowingly agreed to proceed after the refusal. Check any written agreement and state rules before sending a patient bill.
| Group + reason | What it signals | Who usually carries the balance |
|---|---|---|
| CO-39 | Provider went ahead after the plan refused approval | Provider, unless the refusal is overturned |
| PR-39 | Plan holds the member responsible after the refusal | Patient, only with informed agreement and allowed by plan and state rules |
Which remark codes come with CARC 39?
Remark codes with 39 usually point back to the authorization decision or the review behind it.
| Remark code | What it adds | What to check |
|---|---|---|
| N758 | The payment was adjusted to match the prior-authorization decision. | The authorization decision letter and its stated reason |
| N10 | The payment was adjusted after review by a review organization, a professional consultant, a medical advisor or a peer reviewer. | The reviewer's specialty and the review notes |
| N939 | The payer invites you to request a peer-to-peer review (added to the RARC list in July 2026). | Whether a peer-to-peer is still available |
| N54 | Details on the claim do not match what was pre-certified or authorized. | Whether the claim is for what was requested, or a different service |
Where does CARC 39 show up in behavioral health?
In behavioral health, CO-39 most often follows a refused admission or a refused higher level of care where the program treated the patient anyway because discharge was unsafe. It also follows refused TMS courses, psychological testing and ABA hour requests that went ahead at the requested amount.
| Care setting | Typical trigger | Check first |
|---|---|---|
| Residential mental health | Admission refused; program admitted for safety | The refusal letter, the criteria cited and the safety documentation |
| Partial hospitalization (PHP) | Step-up from IOP refused; PHP started anyway | Why IOP failed, in dated notes |
| TMS | Course refused for missing medication trials | Pharmacy and medication-trial history |
| ABA therapy | Requested hours refused; full schedule delivered | Assessment, goals and progress data behind the request |
Corrected claim, reconsideration or appeal: which fits CARC 39?
Appeal the authorization decision, not just the claim. If care is ongoing and waiting would harm the patient, ask for an expedited appeal. For care already delivered, file a post-service appeal that attaches the original refusal, rebuts each reason with records, and explains why treatment could not wait for the outcome.
- 01Get the original refusal notice and the criteria the reviewer used; plans covered by CMS-0057-F must give a specific reason.
- 02Ask for a peer-to-peer if still offered, then file the written appeal within the window in the refusal or the claim notice.
- 03Rebut each stated reason with dated records, and add a treating-clinician letter on why care could not wait.
What evidence resolves a CARC 39?
The evidence is the same as for a medical-necessity appeal, plus the history of the authorization request. Show what was sent at the time, what the reviewer missed or misread, and what happened clinically to the patient while the dispute was still open.
- The authorization request as submitted, with attachments
- The refusal notice, criteria and reviewer details
- Records for the denied dates, mapped to the criteria
- Safety documentation if discharge or step-down was unsafe
- Notes from any peer-to-peer call
How do Medicare, Medicaid and commercial plans differ on CARC 39?
Every program lets you challenge the refusal, but the routes and clocks differ: Medicare Advantage reconsideration, Medicaid managed care appeal and then a state fair hearing, or an ERISA appeal followed by external review. Urgent cases get faster tracks in all three.
| Program | What differs |
|---|---|
| Medicare Advantage | Reconsideration within 60 days of the decision; standard decisions on new requests within 7 days and urgent ones within 72 hours since 2026. |
| Medicaid managed care | One plan appeal within 60 days of the notice, with written member consent if the provider files; then a state fair hearing. |
| Commercial and ERISA plans | At least 180 days to appeal; urgent pre-service claims decided within 72 hours; external review after a final denial. |
CO-39 after a refused PHP step-up
A fictional patient in IOP had two self-harm incidents in a week. The program requested PHP, the plan refused, and the program admitted the patient to PHP anyway. Ten PHP days came back CO-39.
The team appealed the original refusal, not the claims. The packet showed the incident reports, the safety plan revisions and the IOP attendance record, and explained why waiting for the appeal outcome at a lower level of care was unsafe. A psychiatrist reviewed and signed it.
Names, dates, payers and amounts are invented for illustration.
What a ClaimParrot packet does here
- When CARC 39 needs an appeal rather than a corrected claim, an appeal packet answers the payer's stated reason.
- A person checks every packet: $29, or $99 for level of care, and the first is free (pricing).
- No remittances, records or PHI are sent: just the reason and a de-identified summary (Trust & security).
Every draft is reviewed and approved by your team. ClaimParrot does not make medical-necessity determinations or give legal advice.
Frequently asked questions
Should we appeal the CO-39 claim or the authorization refusal?
The refusal. The claim denial follows from it, so reversing the authorization decision is what gets the claim paid. Some plans also need a claim-level appeal or reprocessing request afterwards; ask.
Can we bill the patient after a CO-39 denial?
Only if the group code is PR and the patient knowingly agreed in advance, as the plan and state rules allow. With CO-39, the amount stays with the provider unless the decision is overturned.
How is CARC 39 different from CARC 197?
With 197 the plan found no approval or notice at all. With 39 the plan received the request and said no, so there is a decision with stated reasons to appeal.
Is a CO-39 appeal urgent?
It is if the patient is still in care at the refused level, or needs it. Ask for expedited handling and say why waiting could seriously harm the patient; otherwise use the standard window.
Primary sources and references
- Claim Adjustment Reason Codes (CARC) code list · X12 · checked
- Remittance Advice Remark Codes (RARC) code list · X12 · checked
- CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F) fact sheet · CMS · checked
- 29 CFR 2560.503-1: ERISA claims procedure · eCFR · checked
- 42 CFR 422.582: requesting a Medicare Advantage standard reconsideration · eCFR · checked
- 42 CFR 438.402: Medicaid managed care grievance and appeal system · eCFR · checked
- External review of a health insurer's decision · HealthCare.gov (CMS) · checked
General information, not legal or medical advice. Payer rules change; confirm deadlines and requirements in the notice and the plan documents. Read our editorial policy.
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