CO-185 fires when the specific psychiatric or behavioral health setting where services were delivered was not authorized or is not an approved venue of care under the patient's plan. This is distinct from CO-170 (no authorization at all) — CO-185 applies when the setting itself is the problem: a non-approved facility, a level of care that doesn't match authorization, a carve-out routing error, or a setting restriction that may violate MHPAEA mental health parity rules.
CO-185 means the payer isn't paying because the psychiatric setting where care was delivered wasn't approved — either no one authorized this specific venue, the level of care billed doesn't match what was authorized (e.g., PHP billed when IOP was approved), the claim was sent to the wrong payer (should go to the behavioral health carve-out), or the facility type isn't on the plan's approved psychiatric provider list. CO-185 can also be a MHPAEA parity violation if the setting restriction is more stringent than comparable medical/surgical settings — which is a legally actionable appeal.
CO-170 = no prior authorization was obtained at all for the service. CO-185 = the venue or setting of psychiatric care specifically was not authorized or not approved — which can happen even when some authorization exists. You can have an auth number and still receive CO-185 if the auth covered a different level of care or a different facility than where the patient was treated.
CO-185 can occur at any behavioral health level of care. Each level has a distinct authorization requirement, and payers often require separate authorization for each level even during a single episode of care. The most common CO-185 scenarios involve the settings below:
| Level of Care | Typical Setting | Revenue Code (UB-04) | CO-185 Risk |
|---|---|---|---|
| LOC 1 Acute Inpatient Psychiatric | Locked psychiatric hospital or general hospital psych unit; 24-hour nursing, physician oversight, crisis stabilization | 0114 (Room & Board — Psychiatric), 0900 (Psychiatry — General) | High. Non-approved psychiatric hospitals and general hospital psych units are approved differently. Sending an inpatient claim for a facility not on the plan's inpatient psychiatric approved list generates CO-185 regardless of clinical necessity. |
| LOC 2 Residential Treatment Center (RTC) | 24-hour supervised residential facility; less acute than inpatient; typically not a licensed hospital | 1001 (Residential — Psychiatric), varies by payer | Very high. RTCs are not universally covered. Many plans exclude RTCs entirely or require specific facility licensing. A plan that covers inpatient psych may still deny RTC claims with CO-185 if the RTC is not on their approved residential facility list. |
| LOC 3 Partial Hospitalization Program (PHP) | Hospital-based or free-standing PHP; typically 5–6 hours/day, 4–5 days/week; structured therapeutic programming | 0912 (Partial Hospitalization — Less Intensive) or 0913 (Partial Hospitalization — Intensive) | High. PHP is frequently misauthorized as IOP or vice versa. Payers sometimes issue IOP authorizations when PHP is clinically appropriate, then deny the PHP claims with CO-185 citing level-of-care mismatch. |
| LOC 4 Intensive Outpatient Program (IOP) | Community-based or clinic-based IOP; typically 3 hours/day, 3 days/week; group and individual therapy | 0905 (Intensive Outpatient — Psychiatric) | Moderate. IOP is generally the most commonly covered level; CO-185 at IOP usually means the facility isn't in the plan's behavioral health network or the claim was sent to the medical plan instead of the MBHO. |
| LOC 5 Crisis Stabilization / Crisis Residential | 23-hour observation, crisis stabilization units (CSU), crisis residential programs (CRP) | 0914 (Crisis — Intensive Outpatient) or varies by state/payer | High. Crisis stabilization is a relatively new level of care not uniformly covered. Many plans have not established explicit authorization pathways for CSUs, and CO-185 results from the setting not matching any approved benefit category. |
| Scenario | Why CO-185 Fires | Action | What to Do |
|---|---|---|---|
| Facility not on plan's approved psychiatric provider list | The psychiatric hospital, RTC, or PHP program is not credentialed with or contracted under this specific plan's behavioral health benefit. The plan has no approved facility on file matching your facility's NPI. | Write Off / Contract | Verify your facility's in-network status with this specific plan's behavioral health benefit (not just the medical plan — BH credentialing is often separate). If OON: bill the patient if proper ABN/financial notice was given before admission. If OON due to payer error in your credentialing file, appeal with your contract documentation. |
| Level-of-care mismatch: wrong LOC billed vs. authorized | The payer authorized one level of care (e.g., IOP, 3 hrs/day) but the facility provided and billed a higher level (e.g., PHP, 6 hrs/day). The authorization number is valid but applies to the wrong level of care. | LOC Appeal | Appeal with complete clinical documentation supporting the level of care that was actually delivered: admission assessment, daily notes, staff-to-patient ratio documentation, hours of programming documentation, treatment plan, and clinical justification for PHP vs IOP. If PHP was clinically appropriate, the appeal should explain why PHP criteria were met even though IOP was initially approved. |
| Claim submitted to medical plan instead of BH carve-out MBHO | The patient's behavioral health benefit is managed by a separate MBHO (Managed Behavioral Health Organization). The claim was submitted to the medical plan, which processes it and returns CO-185 because it has no approved psychiatric venue for this benefit. | Reroute Claim | Identify the MBHO from the patient's eligibility response (the BH payer is usually identified in the "other payer" or "BH carve-out" fields of the eligibility transaction — EDI 270/271). Obtain MBHO authorization retroactively if the patient was admitted without contacting the MBHO. Submit the claim to the MBHO, not the medical plan. Watch timely filing — the clock started at DOS. |
| Authorization exists but doesn't explicitly cover the psychiatric setting | An authorization was obtained for the procedure codes (e.g., H0015 for substance abuse IOP, 90853 for group therapy) but did not explicitly name the facility setting or level of care. The payer's system approved the procedure but not the venue. | Appeal | Appeal citing the authorization number and requesting the payer document specifically what the authorization covered. If the auth was for the procedure at this facility type and the denial is splitting the procedure from the setting, this is an administrative denial — appeal with the authorization paperwork showing both the procedure and the requesting facility were submitted together. |
| Residential treatment center not a covered benefit under this plan | The plan simply does not cover residential psychiatric treatment as a benefit category. RTCs are excluded from coverage, meaning any RTC claim generates CO-185 regardless of clinical necessity or prior authorization. | Parity Appeal / Write Off | First, evaluate whether this is a MHPAEA parity violation: does the plan cover comparable medical residential settings (skilled nursing facility, sub-acute rehabilitation) while excluding psychiatric residential? If yes, file a parity appeal. If not (plan excludes all residential care regardless of diagnosis), it is likely a valid exclusion — write off and notify the patient of their appeal rights. |
| Crisis stabilization unit not recognized as an approved setting type | Crisis stabilization units are a relatively new level of care that many payers have not incorporated into their benefit structures. A CSU claim may generate CO-185 because the plan's system has no approved benefit category that maps to a 23-hour crisis stabilization stay. | Appeal / Parity Appeal | Appeal arguing the CSU is clinically equivalent to emergency department psychiatric services, which plans universally cover. Cite MHPAEA: if the plan covers emergency stabilization in a medical ER setting, it cannot deny equivalent psychiatric emergency stabilization in a CSU setting under parity requirements. Request the plan's coverage policy for psychiatric emergencies and compare it to their policy for medical emergencies. |
| Step-down transition: higher LOC not re-authorized before step-down was reversed | A patient was stepped down from inpatient to PHP, but deteriorated and was stepped back up to inpatient. The new inpatient authorization was not obtained before the re-admission, or the re-admission was to a different facility than the original authorization. The re-admission setting generates CO-185. | Emergency Appeal | File an emergency appeal citing the clinical deterioration that necessitated return to inpatient level of care. Provide the clinical documentation of deterioration (nursing notes, physician assessment, safety risk factors). For the authorization gap: if the re-admission was clinically urgent, federal prudent-layperson emergency standards may apply — the plan cannot require pre-authorization for emergent psychiatric care. Cite ACA Section 2719A (prohibits prior auth for emergency services). |
| Medicare/Medicaid setting restriction: service not payable at this psychiatric venue | Medicare and Medicaid have specific rules about which settings can bill for psychiatric services. For example, Medicare covers Partial Hospitalization Programs (PHP) only at hospital-based and CMHC-certified settings — a free-standing PHP that is not Medicare-certified as a hospital-based program or CMHC generates CO-185 for Medicare patients. | Write Off / Certify Setting | For Medicare PHP: verify your program's certification status. Hospital-based PHPs must be operated by a Medicare-participating hospital. Community Mental Health Centers (CMHCs) must be independently certified by CMS. Free-standing PHPs that are neither hospital-based nor CMHC-certified cannot bill PHP to Medicare. If your program can qualify, pursue Medicare certification — it opens a large patient population. For current denied claims: write off; patient can be billed only if proper ABN was issued before service. |
MHPAEA (2008), strengthened by the Consolidated Appropriations Act (CAA 2021), prohibits health plans from imposing non-quantitative treatment limitations (NQTLs) on mental health and substance use disorder benefits that are more restrictive than NQTLs for comparable medical or surgical benefits.
A psychiatric venue restriction is a classic NQTL. If the plan restricts psychiatric residential treatment (CO-185) but covers medical residential settings (skilled nursing facilities, inpatient rehabilitation) without the same restriction — that is a MHPAEA violation. Payers cannot apply more stringent prior authorization requirements, network adequacy standards, or coverage restrictions to behavioral health settings than they apply to analogous medical settings.
Under CAA 2021 Section 203, plans must provide a written comparative analysis of their NQTL design and application upon request. If your CO-185 denial reflects a setting restriction that doesn't exist for medical/surgical equivalents, request this comparative analysis — payers who cannot produce it are in violation.
Identify the comparable medical/surgical benefit: (RTC denial → compare to SNF/inpatient rehab approval; PHP denial → compare to hospital outpatient department day programs; crisis stabilization denial → compare to medical ER coverage). Document that the medical benefit is covered without the same setting restriction. Request the plan's CAA 2021 comparative analysis. File the appeal citing 29 CFR § 2590.712 (ERISA plans) or 45 CFR § 146.136 (ACA plans) and include your comparative analysis showing the asymmetry.
Many commercial plans and large self-insured employer plans carve out mental health and substance use disorder benefits to a separate Managed Behavioral Health Organization (MBHO). The MBHO has its own prior authorization process, its own network of approved psychiatric facilities, and its own claims submission address. Claims submitted to the medical plan — instead of the MBHO — are returned with CO-185 because the medical plan does not administer the behavioral health benefit. Common MBHOs:
The medical and behavioral health benefits may appear to be under the same insurance company but have separate authorization and claims submission processes. Calling the medical plan's phone number and asking for a behavioral health authorization will sometimes result in an authorization for the medical plan's system that is not recognized by the MBHO — generating CO-185 when the claim is correctly submitted to the MBHO. Always call the behavioral health line specifically, confirm which entity will receive the claim, and verify the claim submission address or payer ID for behavioral health claims.
Behavioral health billing is the most complex area of revenue cycle management: carve-out MBHOs, level-of-care authorization requirements, parity law appeals, and setting-specific credentialing all create CO-185 risks that don't exist on medical claims. A free RCM audit reviews your BH claims workflow, identifies MBHO routing errors, flags setting authorization gaps, and evaluates whether your CO-185 write-offs should have been parity appeals.