Medicaid Guide for Behavioral Health

Medicaid

Medicaid (Centers for Medicare & Medicaid Services)

Behavioral health provider guide to Medicaid covering federal/state structure, managed care, IMD exclusion, 1115 waivers, and enrollment.

Quick Reference

Payer Type

Government

Headquarters

Washington, DC

Provider Portal

Open Portal

Portal Guide

View Guide →

Credentialing

State-specific Medicaid enrollment (most states use CAQH)

Timeline

Varies by state (60-180 days)

Coverage

1 states

Last Verified

Mar 15, 2026

Published

Mar 15, 2026

Reading Time

12 min

Covered Levels of Care

• Detoxification (coverage varies by state)
• Residential Treatment (state-dependent, subject to IMD exclusion)
• Partial Hospitalization (PHP)
• Intensive Outpatient (IOP)
• Outpatient Treatment
• Crisis Stabilization
• Medication-Assisted Treatment (MAT)
• Peer Support Services (in participating states)

Medical Necessity Criteria

• State-Specific Clinical Criteria
• ASAM Criteria (adopted by most states for SUD)

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Overview

Medicaid is the largest single payer for behavioral health services in the United States, covering mental health treatment and substance use disorder (SUD) services for approximately 76 million low-income Americans (following post-pandemic Medicaid redeterminations) as of 2025. Established in 1965, Medicaid is a joint federal-state program administered by the Centers for Medicare and Medicaid Services (CMS) at the federal level, with each state designing and operating its own Medicaid program within broad federal guidelines. This federal-state structure creates significant variation in covered services, reimbursement rates, and operational processes across states.

For behavioral health treatment providers, Medicaid is often the dominant payer, particularly for facilities that serve populations affected by substance use disorders, serious mental illness, and co-occurring conditions. Understanding how Medicaid works — including the distinction between fee-for-service and managed care, the role of managed care organizations, behavioral health carve-outs, the Institution for Mental Diseases (IMD) exclusion, and Section 1115 waivers — is fundamental to operating a financially viable treatment program.

This page provides an overview of the Medicaid program as it relates to behavioral health treatment facilities. Because each state administers its own program, the specific details of coverage, enrollment, and billing will vary by state. This guide covers the federal framework and common structures that providers encounter across states, and directs operators to state-specific resources where applicable.

For state-specific routing, start with these Medicaid behavioral health prior authorization and billing guides:

For county-level workflows, use these high-population county guides to verify local access points, court-connected referral context, managed-care routing, and Medicaid billing sources:

Behavioral Health Coverage

Medicaid behavioral health coverage is shaped by both federal requirements and state-specific program design. Federal law requires state Medicaid programs to cover certain mandatory services, including inpatient hospital services, outpatient hospital services, physician services, and for populations under 21, Early and Periodic Screening, Diagnostic and Treatment (EPSDT) services that include comprehensive behavioral health coverage. Beyond mandatory services, states have wide discretion in offering optional services such as residential treatment, intensive outpatient programs, peer support services, and other rehabilitative services.

Most states cover a range of behavioral health services for adults, including outpatient therapy, psychiatric evaluation and medication management, intensive outpatient programs (IOP), partial hospitalization programs (PHP), crisis stabilization, medication-assisted treatment (MAT), and various community-based services. Residential substance use disorder treatment coverage is more complex due to the IMD exclusion (discussed in the next section). Many states also cover peer support services, assertive community treatment (ACT), and psychosocial rehabilitation for Medicaid members.

Medical necessity criteria for behavioral health services vary by state. For substance use disorder treatment, the majority of states have adopted the ASAM Criteria as the standard for level of care placement, either through state regulation, managed care contract requirements, or clinical practice guidelines. For mental health services, states use various clinical criteria including the LOCUS (Level of Care Utilization System), state-developed guidelines, or criteria established by their contracted managed care organizations. Providers must use the medical necessity criteria applicable in their specific state.

The IMD Exclusion

The Institution for Mental Diseases (IMD) exclusion is a federal Medicaid provision that prohibits federal financial participation (FFP) in payments for services provided to Medicaid beneficiaries aged 21 to 64 who are patients in an IMD. An IMD is defined as a hospital, nursing facility, or other institution of more than 16 beds that is primarily engaged in providing diagnosis, treatment, or care of persons with mental diseases. This definition includes many residential SUD treatment facilities.

The IMD exclusion has historically been one of the most significant barriers to Medicaid coverage of residential behavioral health treatment. For facilities with more than 16 beds that provide residential SUD or psychiatric treatment, Medicaid cannot pay for services while the member is a patient in the facility. This effectively means that many residential treatment centers cannot bill Medicaid for services to adult members, even if the member is Medicaid-eligible and the service is medically necessary.

Several important exceptions and workarounds exist. Facilities with 16 or fewer beds are not classified as IMDs and can bill Medicaid without restriction. The IMD exclusion does not apply to members under 21 (covered under EPSDT) or over 64. Many states have obtained Section 1115 demonstration waivers from CMS that allow Medicaid payment for short-term SUD residential stays in IMD facilities, typically for stays of up to 30 days. Additionally, the 2018 SUPPORT Act created a new Medicaid state plan option allowing states to cover SUD treatment in IMDs for up to 30 days without needing an 1115 waiver.

Section 1115 SUD Waivers

Section 1115 demonstration waivers allow states to test innovative approaches to delivering Medicaid services, including waiving the IMD exclusion for SUD residential treatment. CMS has approved 1115 SUD waivers for the majority of states, enabling Medicaid payment for residential SUD treatment in IMD facilities under specified conditions.

The standard conditions of 1115 SUD waivers require states to ensure a continuum of SUD care is available, improve provider capacity, improve access to critical levels of care including residential treatment, use evidence-based SUD-specific patient placement criteria (typically ASAM), and report on quality and access metrics. Waivers typically allow Medicaid payment for SUD residential stays of up to approximately 30 days, though some states have received approval for longer durations and specific terms vary.

Providers should determine whether their state has an active 1115 SUD waiver and understand the specific conditions that apply. Waiver conditions affect which facilities qualify, what levels of care are reimbursable, maximum lengths of stay, and reporting requirements. Contact your state Medicaid agency or visit the CMS website for information about your state’s 1115 waiver status and terms.

Credentialing and Provider Enrollment

Enrolling as a Medicaid behavioral health provider is a two-step process in most states: first, enrolling with the state Medicaid agency, and second, credentialing with individual Medicaid managed care organizations (MCOs) operating in your state. The state-level enrollment is typically a prerequisite for MCO credentialing.

State Medicaid enrollment involves applying through the state Medicaid agency’s provider enrollment portal. Most states have moved to online enrollment systems, and many accept or require CAQH ProView data as part of the application. The enrollment application requires documentation of your facility’s state behavioral health license, accreditation, organizational NPI, Tax ID, ownership and control disclosure (required by federal regulation), liability insurance, and compliance with state-specific facility standards.

Enrollment timelines vary significantly by state, typically ranging from approximately 60 to 180 days depending on the state agency’s processing speed, the completeness of your application, and any site visit requirements. Some states require separate enrollment for each service location, and some require separate enrollment by service type or level of care. Federal regulations generally require Medicaid providers to undergo revalidation every five years and to submit to screening procedures based on risk category, though specific requirements may vary by state.

After completing state Medicaid enrollment, providers must then credential with each Medicaid MCO in their state with which they want to be in-network. Most Medicaid MCOs use CAQH ProView as the credentialing data source, but each MCO manages its own credentialing process independently. In states with multiple Medicaid MCOs, this means potentially credentialing with three to six or more organizations, each with its own timeline and requirements.

Verification of Benefits (VOB)

Verifying Medicaid benefits requires determining the member’s current eligibility status, which managed care plan (if any) the member is enrolled in, and whether behavioral health services are carved out to a separate organization. Medicaid eligibility can change monthly based on income redetermination, and members may be assigned to different managed care plans at different times.

For fee-for-service Medicaid, eligibility can be verified through the state Medicaid agency’s provider portal or through standard HIPAA 270/271 electronic transactions. For managed care Medicaid, eligibility verification should be performed through the assigned MCO’s provider portal or eligibility system. Some states maintain centralized eligibility systems that show the member’s MCO assignment.

Key information to verify includes active Medicaid eligibility on the date of service, the member’s assigned MCO or MBHO, whether behavioral health is carved in to the MCO or carved out to a separate organization, any share of cost or spend-down requirements, whether the member has other insurance (Medicaid is the payer of last resort), and any prior authorization requirements for the intended services.

For behavioral health services, also verify whether the MCO manages behavioral health directly or delegates it to a managed behavioral health organization. If behavioral health is carved out, you may need to verify benefits and obtain authorization through the MBHO rather than the MCO. Document all verification details including the date, method, reference number, and confirmed benefits.

Prior Authorization Requirements

Prior authorization requirements for Medicaid behavioral health services are determined by the state Medicaid program and, where applicable, the member’s assigned MCO or MBHO. Requirements vary widely between states and between managed care plans within the same state. Some states require prior authorization for all facility-based behavioral health services, while others may exempt certain levels of care or allow retrospective authorization in emergency situations.

For fee-for-service Medicaid, authorization requirements and submission methods are defined by the state Medicaid agency. For managed care Medicaid, authorization is managed by the member’s assigned MCO or, in carve-out states, the MBHO. Providers must submit authorization requests to the correct organization using that organization’s preferred submission method (portal, phone, or fax).

Clinical documentation for authorization requests should address the medical necessity criteria adopted by the state and the specific managed care plan. For SUD treatment, document the member’s clinical presentation across the ASAM Criteria dimensions in states that have adopted ASAM as the standard. For mental health services, use the applicable state or plan-specific criteria. Include diagnosis, presenting symptoms, functional impairment, treatment history, current medications, risk assessment, and a clear treatment plan.

Concurrent reviews are standard for residential and inpatient stays under Medicaid managed care. The frequency and process vary by plan. Ensure your clinical team maintains thorough, timely documentation of treatment progress and continued medical necessity to support concurrent reviews. When authorization is denied, Medicaid regulations require written notice with appeal rights. Members have the right to a fair hearing through the state Medicaid agency in addition to any internal plan appeal processes.

Claims and Billing

Medicaid claims submission depends on whether the member is in fee-for-service or managed care. For FFS Medicaid, claims are submitted directly to the state Medicaid agency through its fiscal intermediary. For managed care Medicaid, claims are submitted to the member’s assigned MCO using the MCO’s payer ID and submission requirements. In carve-out states, behavioral health claims are submitted to the MBHO rather than the medical MCO.

All Medicaid claims must follow the state’s billing guidelines for codes, modifiers, and documentation requirements. Institutional claims use the UB-04/837I format, and professional claims use the CMS-1500/837P format. Electronic claims submission through standard EDI 837 transactions is the norm for both FFS and managed care. Ensure you are using the correct payer ID for the member’s specific plan to avoid claim rejections.

Medicaid reimbursement rates are set by each state and are generally lower than commercial insurance rates. Rates may be further negotiated between MCOs and providers in managed care arrangements. Some states use fee-for-service rate schedules as a floor for MCO reimbursement, while others allow MCOs to negotiate independently. Understanding the reimbursement rates in your state and ensuring they support your facility’s cost of operations is an important part of Medicaid participation.

Timely filing deadlines for Medicaid claims are set by state regulation and MCO contracts, typically ranging from approximately 90 to 365 days from the date of service. Medicaid is the payer of last resort, which means that if the member has other insurance coverage, that insurance must be billed first. Only after the primary payer has processed the claim can the remainder be billed to Medicaid. Third-party liability (TPL) denials are common when other insurance was not billed first.

Common Medicaid claim denial reasons include member not eligible on the date of service, missing prior authorization, other insurance not billed first (TPL), incorrect billing codes or modifiers, duplicate claims, and services not covered under the state plan. Track your denial patterns and address systemic issues in your billing processes. For denied claims, file corrected claims for billing errors or formal appeals for clinical denials within the applicable deadlines.

Key Contact Information

Resources:

• Federal Medicaid (CMS): cms.gov/medicaid — federal program information, 1115 waiver status, regulatory guidance
• State Medicaid Agencies: Each state operates its own Medicaid agency — find your state agency through cms.gov or medicaid.gov
• Provider Enrollment: Contact your state Medicaid agency’s provider enrollment division; most states have online enrollment portals
• Managed Care Organizations: Credential and bill through individual MCOs in your state — contact information varies by plan
• Behavioral Health Carve-Out Organizations: In carve-out states, contact the MBHO (such as Carelon or Optum) for behavioral health authorization and claims
• VOB: Verify eligibility through the state Medicaid portal or the member’s assigned MCO provider portal
• IMD Exclusion and 1115 Waivers: Contact your state Medicaid agency or visit medicaid.gov for current waiver status

• CMS Medicaid Provider Enrollment Resources: cms.gov/Medicare-Medicaid-Coordination/Fraud-Prevention/Medicaid-Integrity-Program
• State Medicaid Agency Directory: medicaid.gov
• 1115 Waiver Tracker: kff.org (Kaiser Family Foundation tracks state 1115 waiver approvals)
• ASAM Criteria: asam.org

Frequently Asked Questions

Most states contract with managed care organizations (MCOs) to administer Medicaid benefits, including behavioral health services. Members are generally assigned to an MCO that manages their care, authorizes services, and processes claims. Some states carve out behavioral health to a separate managed behavioral health organization (MBHO). Providers must typically credential and contract with each MCO or MBHO in their state that manages behavioral health for Medicaid members.

The Institution for Mental Diseases (IMD) exclusion is a federal Medicaid rule that prohibits federal financial participation for services provided to members aged 21 to 64 in psychiatric or substance use disorder residential facilities with more than 16 beds. This has historically limited Medicaid coverage for residential treatment. Many states have obtained Section 1115 waivers that allow Medicaid reimbursement for short-term SUD residential stays in IMD facilities, typically for stays of up to approximately 30 days, though specific terms vary by state.

In a carve-in model, behavioral health services are managed by the same MCO that manages the member's medical benefits. In a carve-out model, behavioral health is separated and managed by a specialized managed behavioral health organization (MBHO) such as Carelon or Optum. The model varies by state and can affect which organization providers need to credential with, submit authorizations to, and bill for behavioral health services.

Medicaid is jointly funded by federal and state governments, but each state designs and administers its own program within federal guidelines. This means that covered services, reimbursement rates, authorization requirements, provider enrollment processes, and managed care structures vary significantly between states. A service covered in one state may not be covered in another. Providers must understand their specific state Medicaid program's rules for behavioral health.

In fee-for-service (FFS) Medicaid, providers bill the state Medicaid agency directly for covered services at state-set rates. In managed care Medicaid, providers bill the assigned MCO, which pays according to its contracted rates. Most states have transitioned most Medicaid members to managed care, though some states still operate FFS for certain populations or services. Authorization requirements and billing processes differ between FFS and managed care.

Provider enrollment in Medicaid generally requires application to the state Medicaid agency in each state where you operate. Most states use an online enrollment portal, and many accept CAQH ProView data. Enrollment typically involves verifying your facility license, accreditation, NPI, ownership and control information, and compliance with state-specific requirements. Once enrolled with the state, you can then credential with individual Medicaid MCOs operating in your area.

Key Billing Concepts

Revenue Cycle Resources

This guide is provided for informational purposes only and does not constitute legal, regulatory, or professional advice. Payer requirements, phone numbers, and portal URLs are subject to change. Always verify current information directly with the payer. is not affiliated with the insurance companies described on this page.

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Common questions

Official sources

• Open Portalmedicaid.gov