Claims Adjudication

What claims adjudication is

Claims adjudication is the set of rules and workflows a payer uses to turn a 837 claim into payment, denial, or a request for more information. The process includes validation against benefit design, medical policy, prior authorization records, coordination of benefits, and your contracted fee schedule.

On the back end, adjudication drives creation of the 835 remittance advice and the member's explanation of benefits. Every CARC and RARC code, every adjustment to billed charges, and every patient responsibility amount reflects a specific adjudication rule that fired.

For behavioral health providers, adjudication logic often crosses multiple entities. A primary medical plan may forward to a behavioral-health carve-out vendor, then a separate EAP, then Medicaid as secondary. Each layer runs its own adjudication pass, which is why one date of service can generate multiple remittances and EOBs for the same claim.

Why adjudication matters operationally

Claims adjudication determines cash, days in accounts receivable, and how much gets pushed to patients. A "clean" claim still goes through adjudication. If any rule fails, payment stalls or shifts from payer to patient, or the claim moves into review.

Operationally, adjudication drives:

• Payment timeliness: slow or repeated adjudication cycles can add 15 to 45 days to AR, especially with Medicaid MCOs and carve-outs.
• Denial volume: system edits for missing auth, incorrect POS, or non-covered services feed directly into denial queues.
• Underpayments: fee schedule and bundling logic (for example CO-45 and CO-97) reduce expected payment and can quietly erode margins if not monitored.
• Audit exposure: repeated overrides or manual reviews on high-dollar stays, especially residential and PHP, increase the chance of post-payment audit or recoupment.

When adjudication behavior is not understood, teams chase the wrong fixes. For example, rebilling claims that hit CO-197 for units beyond the authorized days without fixing the underlying authorization just restarts the adjudication cycle and burns days until timely filing runs out.

How adjudication outcomes are used and read

You "see" adjudication results in two places: the payer 835 remittance file and the member's EOB. The key outputs are:

• Claim and line status: paid, partially paid, denied, or pending.
• Adjustment codes: CARCs and RARCs that explain each reduction or denial.
• Patient liability: copays, coinsurance, deductibles, and non-covered amounts pushed to the member.
• Internal references: review flags, audit notes, or medical record requests that live in payer portals.

Operational teams should read adjudication results at the line level, not just the claim total. For example, in a 10-day residential stay, some days may adjudicate to paid per-diem while others deny as "exceeds authorization" or "non-covered level of care." If patient responsibility is assigned incorrectly during adjudication, you risk both overbilling patients and under-appealing payers.

Over time, patterns in adjudication outputs inform contract negotiations, authorization workflows, and clinical documentation standards. Repeated CO-16 with N130 or MA130, or CO-109 on certain ASAM-mapped levels, signals where front-end processes or clinical narratives need to change, not just where follow-up staff need to work harder.

• Treating "paid" claims as fully resolved without reviewing the CARC and RARC detail on long-stay residential claims, which hides underpayments from CO-45 contractual adjustments and CO-97 bundling on key service days.
• Ignoring line-level adjudication on PHP or IOP episodes where some days deny with CO-197 for exceeding authorization while other days pay, which leaves partial denials unworked and distorts denial-rate reporting.
• Assuming the primary medical payer's adjudication is final on behavioral-health claims, and failing to bill or track the behavioral-health carve-out plan or Medicaid secondary after the initial 835 posts.
• Rebilling claims that received CO-16 with N130 or MA130 without fixing the missing information or attachment, which only generates repeat denials, wastes timely filing window, and clogs AR reports.
• Posting patient responsibility from the EOB on Medicaid and Medicaid MCO claims without checking state rules on cost sharing for behavioral health, which can lead to inappropriate patient billing and compliance risk.

Behavioral health claims often hit more complex adjudication paths than standard medical claims. Many commercial plans outsource mental health and substance use benefits to carve-out vendors, so the same visit or stay may adjudicate in two systems: the medical payer that receives the 837 and the behavioral-health vendor that actually pays or denies. If staff do not track both layers, paid claims at the primary plan can still be denied or underpaid at the carve-out stage.

Concurrent authorization is a major driver of adjudication outcomes in residential, PHP, and IOP. Payers frequently approve a limited number of days or units and then rely on concurrent review to extend coverage. Adjudication logic will automatically cut off payment on days that exceed approved units, often with CO-197 or related codes. Without tight coordination between utilization review, billing, and posting, those denials look like generic payment issues instead of predictable outcomes of expired auth.

Long per-diem episodes, such as 30-day residential or extended IOP, expose issues in daily claim submission strategies. Some Medicaid and Medicaid MCO programs want a single institutional claim for the full stay, while others want daily or weekly billing. Adjudication rules follow those program standards. Submitting the wrong pattern can lead to partial adjudication, repeats of CO-16 or CO-96, and complex recoups when the program later reprocesses the stay.

State Medicaid programs and their MCOs also overlay policy rules specific to behavioral health: IMD exclusions, SUD waiver limits, and level-of-care requirements commonly mapped to ASAM criteria. Adjudication engines apply these rules mechanically. If documentation or coding does not match the required criteria, payment can be cut even when clinical care was appropriate, and appeals must explicitly address the policy language that triggered the denial.

For claims adjudication, AI agents shine at reading and structuring the outputs. An AI can ingest every 835, classify CARC and RARC codes by root cause, and flag which denials come from benefit rules, which from missing authorization, and which from coding or data errors. Over time, that analysis turns opaque payer behavior into concrete patterns your team can act on.

Supabill's claims-scrubbing and denials agents use stored payer rules and past adjudication patterns to prevent avoidable edits before submission, then to organize every adjudication outcome into clear work queues. The agents can highlight when a behavioral-health stay was cut short for auth reasons, or when a specific MCO quietly changed its bundling logic. Humans still own the judgment calls: interpreting ambiguous policy language, deciding which cases to appeal, calling payers or carve-out vendors, and negotiating contract or authorization workflow changes that an AI cannot handle.

What actually happens during claims adjudication at a payer?

During claims adjudication, the payer validates the claim data, checks member eligibility and benefits, applies coordination of benefits rules, compares the billed services against medical policy and prior authorization records, prices the claim against the contract or fee schedule, and then calculates payment, adjustments, and patient responsibility. For Medicare Fee-for-Service, many of these steps are defined in national and local coverage policies and administered through automated and manual review programs described by the Centers for Medicare & Medicaid Services (CMS).

How long does claims adjudication usually take?

Adjudication timelines vary by payer, product, and whether the claim is considered "clean." Medicare and many commercial plans have standards that require timely processing of clean claims, often within a set number of days for electronic submissions, while claims that pend for medical review, attachments, or coordination of benefits can take significantly longer. State Medicaid programs and their managed care plans may have their own timelines set by contract or regulation, so behavioral health providers should confirm expectations with each payer program.

How can I tell from the 835 remittance what happened in adjudication?

The 835 remittance advice encodes adjudication results at the claim and service-line levels through a combination of payment amounts, adjustment reason codes (CARCs), and remark codes (RARCs). By reviewing the CARC and RARC pairs on each line, you can see whether the payer reduced payment due to contract terms, benefit limits, medical policy, missing information, or coordination of benefits. The X12 standard defines the structure of these segments, while each payer publishes its own crosswalks and policy links that explain how specific code combinations map to adjudication rules.

Are behavioral health claims adjudicated differently from medical claims?

Behavioral health claims often run through additional layers in adjudication. Many commercial plans use specialized behavioral-health vendors or EAPs, so mental health and SUD services can be carved out and adjudicated separately from medical services. State Medicaid programs also apply policy rules specific to behavioral health, such as waiver requirements, IMD limitations, and level-of-care criteria. These structures mean more frequent checks against prior authorization, visit limits, and medical necessity criteria for services like residential treatment, PHP, and IOP. Source

What should a billing team do when adjudication results do not match clinical expectations?

When adjudication results seem misaligned with the care provided, start with a structured read of the remittance: identify the specific CARC and RARC codes, confirm benefit and authorization details, and compare the payer's stated reason to medical policy or program rules. For behavioral health, pay close attention to level-of-care criteria, visit limits, and concurrent authorization notes. If the denial or reduction conflicts with the documented clinical picture or policy language, escalate to appeal with strong clinical documentation, and coordinate with utilization review or medical leadership as needed. Source

• Medicaid.gov, Medicaid
• SAMHSA, Behavioral Health Services