Peer-to-Peer Review

What a peer-to-peer review is

Peer-to-peer review is a scheduled call between the treating clinician and a payer clinician, such as a medical director or psychologist, to discuss coverage for a specific patient episode. The goal is to align on medical necessity, level-of-care, or continued-stay criteria using clinical information that often does not fit cleanly in a form or fax.

The payer usually offers peer-to-peer review when a service is about to be denied or reduced, most often for authorization or medical-necessity reasons. In behavioral health, that is frequently around admission, continued residential days, or step-down levels, like PHP or IOP.

The outcome of the call can be:

• Upheld denial or reduced authorization
• Partial approval, such as fewer days or a lower level-of-care
• Full approval for the requested days, units, or level-of-care

The decision then flows into claim payment. A strong peer-to-peer review can rescue tens of thousands of dollars in per-diem or high-intensity care that would otherwise write off.

Why peer-to-peer reviews matter operationally

Peer-to-peer review lives at the intersection of utilization management and revenue cycle. When you win, you convert what would have been a denial into collectible revenue. When you miss the window, you lock in avoidable write-offs and future audit risk.

Operationally, peer-to-peer reviews affect:

• Cash: Lost days for residential, PHP, or IOP translate directly into unbillable per-diem or unit-denied claims.
• AR aging: If peer-to-peer review happens after an initial denial, every roundtrip can add 30 to 60 days before you see payment.
• Clinical operations: If the payer refuses higher levels-of-care, your team may need to discharge or step down patients earlier than clinically ideal.
• Compliance and audit posture: Sloppy documentation of peer-to-peer outcomes can create discrepancies between what the payer authorized and what your EHR shows as planned or delivered.

Peer-to-peer review is also a scarce resource. It consumes physician or senior clinician time. If you schedule poorly, you burn clinical capacity and still lose the denial. Treat it as a high-value, last-chance tool, not something triggered haphazardly for every adverse determination.

How peer-to-peer reviews usually work

Most payers outline the peer-to-peer process in the authorization notice or denial letter. Common patterns:

• A short request window, sometimes as tight as 24 to 72 hours after a denial or adverse determination.
• Specific instructions on who may participate, such as attending physician, psychiatrist, or licensed clinician.
• A scheduling workflow, such as direct call-in, online scheduling, or a callback request.

Operational best practices:

• Triage which cases merit P2P: High-dollar episodes, long residential stays, or high-risk patients deserve priority.
• Prepare a concise clinical brief: Reason for admission, risk factors, ASAM or LOCUS scores, response to treatment, and discharge barriers.
• Align the story to criteria: Use the payer's own medical-necessity or level-of-care criteria when possible.
• Document the outcome in real time: Names, date and time, what was approved, and any conditions or planned follow-up.

Your utilization management and RCM teams should work from a shared playbook. Denial codes like CO-50 or CO-197, or auth notices that cut days, should route directly into a queue where a human decides whether to request peer-to-peer and by when. Supabill's denials agent can help here by reading every 835 and flagging medical-necessity and auth-related denials, so you are not relying on manual report runs to catch them.

Behavioral health specifics: carve-outs, concurrent auth, and long stays

Behavioral health sees peer-to-peer reviews at a higher frequency than many medical specialties because benefit designs push more utilization management into separate behavioral health vendors. Commercial and Medicaid plans often carve out behavioral health to entities that run aggressive concurrent review, such as daily or every few days in residential or inpatient psych.

For long per-diem episodes, like residential SUD or mental health treatment, peer-to-peer reviews often occur at key utilization checkpoints. The payer may approve an initial block of days, then require additional clinical information. If the reviewer believes the patient no longer meets criteria at that level, the payer may offer a step-down (for example, to PHP) or terminate continued-stay authorization. Missing or mishandling that peer-to-peer window can strip out the back half of a stay from payment.

Concurrent authorization is a special pain point. A clean claim can still deny for days that fall after the last authorized date, even if the payer previously paid earlier days. Peer-to-peer review is often the only practical path to restore coverage for those late episode days, especially with state Medicaid and MCOs that rigidly apply their criteria.

Behavioral health teams must also navigate varied provider types. Some payers require an MD or DO for peer-to-peer. Others accept a psychologist, psychiatric NP, or licensed therapist. Residential and SUD programs should maintain a clear escalation tree so that someone who meets payer requirements is always available inside the narrow scheduling window.

How AI can help with peer-to-peer review

AI cannot make the peer-to-peer call, and it should not replace clinical judgment. What it can do is handle the prep and tracking work so your clinicians use their time on persuasion, not admin. An AI agent can pull the latest clinical notes, prior auth history, and payer criteria, then assemble a tight, structured summary that highlights risk, level-of-care need, and treatment response.

Supabill's denials agent can flag likely peer-to-peer candidates by classifying CARC and RARC codes tied to medical necessity and authorization, then group them by payer and deadline. Supanote can help clinicians create consistent, criteria-based documentation, so the story they tell on the call lines up with what exists in the chart. Humans still own strategy, case selection, clinical reasoning, and the live conversation, especially in complex behavioral health cases where nuance and real-time negotiation matter.

• Letting the peer-to-peer window expire because no one tracks the request deadline on the denial letter, so a CO-197 or CO-50 denial becomes final and the team is forced into a weaker written appeal or straight write-off.
• Sending a clinician to the call without payer-specific criteria or scores, such as ASAM or LOCUS, which leads to a vague narrative about the patient being "not ready" instead of a structured, criteria-based argument that payers will accept.
• Failing to document the outcome in the EHR and billing system, so utilization and billing staff keep requesting or delivering services that the payer just denied, adding unbillable days and confusion in later audits.
• Assuming any licensed staff member can complete the peer-to-peer, then finding out mid-call that the payer requires an MD or specific credential, wasting the slot and losing the chance to overturn the denial.
• Not coordinating with scheduling and discharge planning after a partial approval, such as when a payer approves only three more residential days, which leaves the patient in a limbo where clinical plans and authorized days no longer match.

Behavioral health payers rely heavily on peer-to-peer review to control high-cost levels-of-care like inpatient psych, residential, and PHP. Behavioral health carve-out vendors commonly use proprietary or adapted criteria layered on top of ASAM or LOCUS, and peer-to-peer review is where those criteria get interpreted and negotiated.

Long per-diem episodes create large-dollar swings around a single call. Losing peer-to-peer for the back half of a 30-day residential SUD stay can convert half the episode into either self-pay or write-offs. That is especially painful in Medicaid and Medicaid MCO programs, where rates are already low and denial reversal outside the peer-to-peer window can be difficult.

Concurrent authorization compounds the issue. For example, a Medicaid MCO may only initially approve 7 days of residential care, then require ongoing reviews every 3 to 7 days. If the payer cuts off days 15 through 21 and offers a peer-to-peer call, your ability to keep those days billable depends almost entirely on how well your clinician presents clinical risk, utilization, and discharge barriers.

State Medicaid and MCO rules often specify tight timelines and credentials for peer-to-peer participation, and some require exhaustion of this option before a formal appeal. Behavioral health programs should build payer-specific playbooks, including who is allowed on calls, typical clinical thresholds, and how many days or hours are usually at stake, so the team can prioritize smartly.

AI can help with peer-to-peer review by handling the data gathering and prep that usually slows clinicians down. An AI agent can scan recent progress notes, risk assessments, ASAM or LOCUS scores, and prior auth decisions, then generate a concise, criteria-aligned brief that surfaces the exact elements a payer reviewer is looking for. It can also monitor denial feeds and auth cut-down notices, calculate when the peer-to-peer window closes, and push clear tasks to your utilization and clinical teams.

Supabill's denials agent reads each 835 and classifies CARC and RARC codes so that medical-necessity and authorization issues feeding peer-to-peer review do not fall through the cracks. Combined with Supanote, clinicians can anchor their documentation to payer criteria in everyday notes, so the case they present on a call is already supported in the chart. The limit is that AI cannot negotiate with the payer or make judgment calls on whether to accept a lower level-of-care, so your human clinicians still own the strategy, the call, and the final go/no-go decisions.

Is a peer-to-peer review required before filing a formal appeal?

Peer-to-peer review is usually optional but strongly encouraged by many payers as an informal or expedited resolution step before a formal written appeal. Some Medicare Advantage and Medicaid managed care plans require that you use available reconsideration or discussion steps, which may include peer-to-peer, before escalating. You should confirm the requirements in each payer's provider manual and in the adverse determination notice. For federal programs, overall appeal structures are described in CMS guidance on appeals and grievances, but peer-to-peer itself is usually a plan-level policy rather than a statutory requirement.

Who is allowed to participate in a behavioral health peer-to-peer review call?

Allowed participants depend on the payer and the benefit type. Many commercial and Medicaid behavioral health payers require the attending or supervising clinician at the level of care in question, such as a psychiatrist, clinical psychologist, or psychiatric nurse practitioner. Some plans accept licensed therapists for outpatient or IOP levels, while requiring an MD or DO for inpatient psych or residential. The authorization letter or provider manual usually specifies minimum credentials. If your program uses multidisciplinary teams, maintain a roster of clinicians who meet each payer's peer-to-peer requirements so you can schedule within tight windows. Source

How much time do we typically have to request a peer-to-peer review after an adverse determination?

Many payers give a very short timeframe, such as 24 to 72 hours from the date of the adverse determination for concurrent reviews, or a defined number of business days for retrospective denials. There is no universal standard, and timeframes differ between commercial, Medicare Advantage, and Medicaid managed care plans. Treat the timeline printed in the authorization reduction notice or denial letter as authoritative, and build internal workflows that surface those deadlines the same day the notice arrives, so your clinical and UM teams can decide quickly whether to request peer-to-peer.

What should be documented after a peer-to-peer review in behavioral health settings?

After every peer-to-peer call, document at least: date and time of the call, names and credentials of the payer reviewer and treating clinician, a brief summary of clinical points discussed, the final decision, specific dates or units approved or denied, and any instructions for follow-up or step-down. That summary should live both in the clinical record and in your authorization or billing system. Solid documentation reduces later disputes over what was approved and supports you if the case escalates to a formal appeal or a Medicaid or Medicare audit.

Can peer-to-peer review overturn a retrospective denial for a behavioral health stay under Medicaid or a Medicaid MCO?

In some Medicaid and Medicaid managed care programs, peer-to-peer review is available for retrospective denials, particularly for disputes over medical necessity or level-of-care. However, once the formal denial and appeal clock has started, plans may limit you to written reconsiderations or appeals instead of live clinical discussions. Check the denial notice and the managed care contract or provider manual to see if peer-to-peer remains an option after claim adjudication. Even when allowed, reversal rates can be lower than for concurrent reviews, so quick engagement during the initial adverse determination stage usually gives you a better chance of success. Source

• Medicaid.gov, Managed Care Appeals & Grievances
• SAMHSA, Treatment