A behavioral health denial usually arrives on a code that points at the paperwork rather than the care. The authorization is written for a service, a provider and a number of units, and the claim has to match all three. A unit is a slice of face-to-face time rather than a session, so the note has to prove the boundaries. When any one of those pieces does not line up, the claim does not argue. It denies.
What this covers
- Most behavioral health denials trace back to a mismatch between what the payer approved and what the claim says.
- Authorization denials arrive on separate codes: CARC 197 when none exists, CARC 198 when the service outgrew it, CARC 302 when it expired.
- The CMS Medicare NCCI table caps 97153 at 32 units on one date of service and 97151 at 8, while state Medicaid programs add weekly ceilings of their own.
- CARC 185 and the N28x remark codes point at the rendering provider, which in ABA is often a technician rather than the supervising clinician.
- A note without start and stop times cannot support a time-based code, whether that code is 90834 or 97153.
An authorization covers a service, a provider and a number of units. The claim has to match all three.most behavioral health denials are a mismatch between the approval and the bill
Six reasons carry most behavioral health denials: authorization, units, rendering provider, documentation, medical necessity and bundling. Each leaves a different trail on the remittance and each has a different fix. Read the code before you write the appeal, because the code says which of the six you have.
Why behavioral health denials behave differently
Behavioral health is billed on time and on units. Psychotherapy is reported by session length: 90832 covers 16 to 37 minutes with the patient, 90834 covers 38 to 52 minutes, and 90837 covers 53 minutes or more. Applied behavior analysis is reported in 15-minute units. The unit of payment is small and the volume is high, so one wrong field repeats across hundreds of lines.
Two layers sit on top of that. Nearly every service needs prior authorization, and a supervision layer sits behind it, because the person who delivers the care is often not the person who bills it. Medicare Advantage insurers denied 7.7 percent of the 52.8 million prior authorization requests they received in 2024, and 80.7 percent of the denials that were appealed were overturned. KFF notes that a high overturn rate can also mean the first request lacked the documentation to support it.
| What went wrong | The code | What it means | The fix |
|---|---|---|---|
| Authorization absent | CO-197 | No approval on file | Retroactive request, then appeal with clinical notes |
| Authorization exceeded | CO-198 | Service outgrew the approval | More units or an extension, or appeal with justification |
| Authorization expired | CO-302 | The time limit ran out | Check the end date when you schedule |
| Units beyond the record | CO-151 with N206 | Record does not support the volume | Reconcile units to documented time |
| Rendering provider not enrolled | CO-185 with N767 | Provider not eligible in that state | Enroll the technician, then correct and resubmit |
| Documentation missing | CO-16 with N706 | Records requested and not received | Send the record inside the development window |
| Medical necessity disputed | CO-50 with N661 | Record does not show necessity | Appeal with the plan of care and progress data |
| Two services, one payment | CO-97 | Benefit included in another service | Check the code pair and its modifier indicator |
Since January 1, 2026, payers affected by the CMS interoperability rule must give a specific reason for a denied prior authorization, whatever channel the request came through.
Reason one: the authorization does not match the service
Two authorization failures look alike on a worklist and need different answers. CARC 197 means no approval was on file when the claim processed. CARC 198 means an approval existed and the service went past it. CARC 302 covers an approval that ran out of time, and CARC 296 covers a valid number that does not apply to the provider billed. CARC 15, the retired missing-authorization-number code, was deactivated in 2018.
The response depends on which one you have. An absent authorization needs a retroactive request where the plan allows one, and a clinical appeal where it does not. An exceeded authorization needs more units or an extension. An expired approval needs a date check before the next visit.
One row per approval: number, covered codes, units approved, units consumed, start date, end date and the provider named on it.
Start the reauthorization at a defined threshold rather than at exhaustion.
The provider named on the approval has to be the provider in the rendering field.
The decision clocks are set in regulation. Under 42 CFR 438.210, a Medicaid managed care plan has 72 hours for an expedited authorization and no more than 7 calendar days for a standard one when the rating period starts on or after January 1, 2026. Medicare Advantage runs on the same windows under 42 CFR 422.568 and 422.572.
Nevada Medicaid states it plainly: authorization does not guarantee payment of a claim, because payment also depends on eligibility, available benefits and the provider agreement.
Reason two: the units do not reconcile
A unit of ABA treatment is 15 minutes of face-to-face time, and 97153 carries most of the volume in a practice. A note that records two hours of ABA without start and stop times cannot be audited into eight units, because the payer rebuilds units from the boundaries in the record.
| Code | What it describes | Medicare MUE per date of service |
|---|---|---|
| 97151 | Behavior identification assessment | 8 |
| 97152 | Supporting assessment with technician support | 16 |
| 97153 | Adaptive behavior treatment by protocol, one patient | 32 |
| 97154 | Group adaptive behavior treatment | 18 |
| 97155 | Treatment with protocol modification | 24 |
| 97156 | Family guidance, one family | 16 |
| 97157 | Multiple-family group guidance | 16 |
| 97158 | Group treatment with protocol modification | 16 |
| 0362T | Assessment requiring two or more technicians | 16 |
| 0373T | Treatment requiring two or more technicians | 24 |
A medically unlikely edit is the maximum units of service reported for a code on the vast majority of appropriately reported claims, for the same provider and beneficiary on the same date of service. The values come from the CMS Medicare NCCI practitioner table, refreshed quarterly.
State programs add ceilings of their own. Nevada Medicaid caps ABA at 15 to 25 hours per week under a focused delivery model and 25 to 40 under a comprehensive one, applied to the combined units of 97153, 97155 and 0373T. A combined limit of 40 hours per recipient per week applies across 0373T and 97153 through 97158.
Unit mismatches arrive on their own codes. M53 says the days or units are missing, incomplete or invalid. N430 says the procedure code is inconsistent with the units billed, and N362 says the units exceed the payer’s maximum.
- Start and stop times on every time-based service, written in the note
- Billed units derived from documented minutes
- A daily check against the MUE, and the state weekly ceiling where one applies
- A weekly count of units consumed against units authorized, per patient
Reason three: the rendering provider is wrong
In applied behavior analysis the technician usually delivers the service and the clinician owns the plan, and payers do not agree on which of them belongs in the rendering field. New York Medicaid requires the certified behavior analyst assistant’s NPI as the rendering provider, with the licensed analyst as the billing and supervising provider. Nevada Medicaid asks for the NPI of the actual provider of the service rather than the supervising clinician.
The denials look like credentialing problems, and often they are. CARC 185 means the rendering provider is not eligible to perform the service billed. RARC N288 through N291 point at the taxonomy, name or identifier on the claim. N767 says the state requires enrollment before the claim will process, and N852 says the two tax identification numbers do not match.
Technicians change jobs faster than payer enrollment cycles, so a practice can be fully enrolled on paper in January and billing with an unenrolled rendering provider by March.
Keep a rendering-provider grid: every technician and clinician, the codes they are enrolled and certified to render, their NPI, their taxonomy, and the date each item expires.
Reason four: the note cannot support the code
A time-based code needs the time in the record. The First Coast billing and coding article for psychiatric diagnostic evaluation and psychotherapy states that start and stop times, or total times, must be documented for 90832, 90834 and 90837, and that psychotherapy of less than 16 minutes should not be reported at all.
For ABA the list is set by the payer and it is specific. The New York Medicaid ABA manual asks for the treatment plan with its assessment and goals, specific goals with the data that measures progress, total hours of service per week with the mix of staff who delivered them, and the locations of service. It caps supervision at six assistants per analyst and requires supervision for at least 5 percent of the hours delivered.
- Start and stop times, or total time, for every time-based service
- The rendering provider’s name and credentials on each note
- The intervention targeted and the patient’s response, with the data behind it
- Supervision contacts, dated, with the method used
Documentation denials arrive as RARC N706 for missing documentation and N705 for documentation that is incomplete or invalid. N206 says the record you sent does not match the information on the claim, which turns a missing item into a credibility question.
Reason five: medical necessity is disputed
A medical necessity denial is not a statement that the service was not delivered. CARC 50 reads: these are non-covered services because this is not deemed a medical necessity by the payer. The reviewer is applying coverage criteria to the record, and behavioral health criteria are written at the level of care and the plan of care.
Two codes sit under most of these denials. RARC N661 says the documentation does not support that the services rendered were medically necessary. CARC 39 means the payer denied the authorization when it was requested, so the appeal has to argue the clinical case rather than a missing field.
The assessment that established the diagnosis, the plan of care with measurable goals, the progress data since the last review, and the criterion the payer says it applied. Attach the authorization and the denial to the same appeal.
Ask for the criteria in writing. A payer that has to give a specific reason has to name the rule it applied, and the named rule tells you whether the denial is correctable with a record or has to be argued. Denial management is where that loop closes.
Reason six: two services became one payment
CARC 97 means the benefit for a service is included in the payment for another service that has already been adjudicated. The mechanism is the NCCI procedure-to-procedure edit: when both codes are reported for the same patient on the same date, the Column 1 code is eligible for payment and the Column 2 code denies.
The modifier indicator on the edit decides whether a modifier can change that, and an indicator of 0 means no modifier will. In the current Medicare NCCI practitioner file, 90791 is the Column 1 code against 90832, 90834, 90837, 90853 and every ABA treatment code from 97151 through 97157, all at indicator 0.
One overlap is not covered by an edit. There is no current NCCI pair between 97153 and 97155, so nothing automated stops you from billing the technician’s direct service and the clinician’s protocol modification for the same 15 minutes. The code definitions stop it, because both describe face-to-face time with the same patient.
The fix sits upstream of the claim. Check the code pair against the current edit file before you bill, and put the overlapping-time rule into the scheduling template. Behavioral health revenue cycle management runs the authorization register, the rendering-provider grid and the code-pair check as one process. If any of the six reasons is showing up on more than a handful of claims a month, we will map it with you.
Behavioral health denial questions
The billing unit is smaller and the controls sit in front of it. Psychotherapy is reported by session length and ABA is reported in 15-minute units, so the note has to prove the time. Most services also need prior authorization, and the technician who delivers the service is often not the provider who bills it. Each layer is a place where a claim fails on a field.
CARC 197 means precertification, authorization, notification or pretreatment was absent, so no approval was on file when the claim processed. CARC 198 means the approval existed and the claim went beyond it, in units, visits or dates. An absent authorization usually needs a retroactive request or a clinical appeal, while an exceeded authorization needs more units or an extension.
The CMS Medicare NCCI practitioner table sets a medically unlikely edit of 32 units for 97153, which is eight hours of face-to-face time. State Medicaid programs apply their own ceilings on top. Nevada Medicaid caps combined weekly hours across 97153, 97155 and 0373T and limits each servicing provider to 12 billable hours in a day. Check the current quarter’s edit file and your state manual.
No. The two codes describe different services delivered by different people, and both describe face-to-face time with the same patient, so the same minutes cannot be both. The current Medicare NCCI practitioner file carries no edit pair between them, which means no automated edit will catch the overlap for you. Payers see it in the claims data.
It depends on the payer, and the difference is not optional. New York Medicaid reports the certified behavior analyst assistant’s NPI as the rendering provider, with the licensed analyst as the billing and supervising provider, while non-enrolled aides bill under the analyst’s NPI for all three fields. Nevada Medicaid requires the NPI of the actual provider of the service. Document the rule per payer.
Under 42 CFR 424.44, a Medicare fee-for-service claim must be filed no later than the close of the period ending one calendar year after the date of service. Commercial and Medicaid limits are set by contract and state policy rather than by that regulation, so they have to be checked payer by payer. A claim that pends never appears on a denial report while the filing clock runs.
The bottom line
Behavioral health denials are repetitive, and that is the useful part. The same six mismatches produce the same codes on the same payers, month after month, so a fix to the authorization register or the rendering-provider grid pays out on every claim that follows. Read the reason code first, correct the record second, and appeal only what the record cannot fix.
Which of the six is costing you the most?
Send us one month of behavioral health remittances and your authorization register. We will group the denials by reason, show you which ones are correctable before the next claim goes out, and tell you what the recovery is worth.
Request a free behavioral health denial auditThis article describes general billing practice rather than legal or clinical advice. Authorization rules, unit limits, documentation requirements and filing deadlines vary by payer, state and contract, so confirm them against the current provider manual and your participation agreement.
