You're in the middle of a claim review, the payer is asking for documentation on a 90837, and you need to verify the time threshold and modifier requirements right now. Or you're training new billing staff and need a single resource that covers the CPT codes, HCPCS codes, and modifiers they'll use every single day. This is that resource.
This reference guide covers the CPT codes addiction treatment billing 2026 essentials: assessment codes, therapy codes, MAT billing, IOP/PHP codes, and the modifiers that make or break reimbursement. It's organized by service category so you can find what you need in seconds, with the credential requirements and documentation flags that actually matter when claims get reviewed.
Assessment and Intake Codes: H0001, 90791, 96130
The first billable encounter sets the tone for the entire episode of care. Three codes dominate addiction treatment assessments, and choosing the wrong one costs you money or triggers denials.
H0001 is the HCPCS code for comprehensive alcohol and drug assessment. It's typically used by Medicaid and some commercial payers, covers the full biopsychosocial intake including ASAM criteria determination, and usually requires a licensed clinician (LCSW, LPC, LMFT, or higher). Documentation must include substance use history, mental health screening, medical history, risk assessment, and preliminary treatment plan. Typical reimbursement ranges from $150 to $300 depending on state Medicaid rates.
90791 is the CPT code for psychiatric diagnostic evaluation without medical services. It's accepted by Medicare, most commercial payers, and many Medicaid plans. This code requires a licensed mental health professional and covers a comprehensive assessment including mental status exam, diagnostic formulation, and treatment planning. Time is not a factor for this code, but documentation must support medical necessity for the level of evaluation. Most payers reimburse between $200 and $350.
96130 and the related series (96136, 96138, 96139) cover psychological testing evaluation services. These codes are rarely used in routine addiction treatment intake but become relevant when cognitive impairment, co-occurring disorders, or forensic evaluations require formal testing. They require a psychologist or appropriately credentialed provider and detailed documentation of test administration, scoring, and interpretation. According to the American Medical Association behavioral health coding guide, these codes have specific time-based components and credential requirements that vary by payer.
The most common denial trigger for assessment codes: billing 90791 and H0001 for the same patient on the same date of service. Pick one based on payer requirements and your clinician's credentials.
Individual Therapy Codes for Substance Use Disorder Treatment
Individual therapy is the backbone of outpatient addiction treatment billing. Three CPT codes cover most sessions, and the only difference between them is time. Get the time documentation wrong, and you're looking at downcodes or denials.
90832 covers 16-37 minutes of psychotherapy. If your clinician documents 15 minutes, you can't bill this code. If they document 38 minutes, you should be billing 90834 instead. The time threshold matters, and missing it is one of the most common billing errors treatment centers make.
90834 covers 38-52 minutes of psychotherapy. This is the workhorse code for standard 45-minute individual sessions. Documentation must include start and stop times (or total duration), presenting problem, interventions used, patient response, and plan for next session.
90837 covers 53 minutes or more of psychotherapy. This code requires documentation of at least 53 minutes of face-to-face time. Payers audit this code heavily because the reimbursement difference between 90834 and 90837 can be $40 to $60 per session. If your note says "approximately one hour" without specific times, expect a denial on review.
All three codes can be billed by licensed therapists (LCSW, LPC, LMFT, psychologists, psychiatrists). Unlicensed clinicians working under supervision cannot bill these codes under their own NPI in most states.
Place of service matters. POS 11 is office, POS 53 is community mental health center, POS 57 is non-residential substance abuse treatment facility. Using the wrong POS code can trigger rate differences or denials depending on your facility licensure and payer contracts.
Telehealth billing: As of 2026, most payers still accept modifier 95 or GT for telehealth sessions. The POS code stays as your primary location (usually 11 or 57), and the modifier signals the audio-video delivery. Some payers moved to POS 02 (telehealth) during COVID flexibilities, but most have reverted. Check your specific payer policies before submitting.
Group Therapy Codes: 90853, H0005, S9480
Group therapy delivers clinical value and margin, but only if you bill it correctly. Three codes cover most group sessions, and payers are increasingly strict about which one you can use.
90853 is the CPT code for group psychotherapy. It's accepted by Medicare, most commercial payers, and many state Medicaid programs. It's billed per patient, per session, regardless of group size. The code does not specify a minimum or maximum group size, but many payers have internal policies limiting reimbursement if groups exceed 12-15 participants. Documentation must include group topic, therapeutic interventions, individual patient participation notes, and clinical rationale.
H0005 is the HCPCS code for alcohol and drug services in group settings. It's primarily used by Medicaid and some commercial payers who prefer HCPCS codes for substance use disorder services. Like 90853, it's billed per patient per session. Reimbursement is typically lower than 90853, ranging from $25 to $60 depending on state rates. Some states require H0005 instead of 90853 for SUD-specific groups; check your Medicaid manual.
S9480 is an S-code for intensive outpatient services including group counseling. Some commercial payers use this as a bundled per-diem code rather than billing individual group sessions separately. It's not recognized by Medicare or most Medicaid programs. If your commercial contracts reference S9480, clarify whether it replaces or supplements individual service billing.
Telehealth modifiers for group therapy: Modifier 95 or GT applies to group therapy delivered via telehealth. However, some payers implemented policies in 2024-2025 limiting telehealth reimbursement for group services or requiring at least partial in-person attendance. The CMS mental health coverage guidelines provide baseline standards, but commercial payers often have stricter requirements.
The biggest denial risk: billing group therapy for a patient who was not clinically engaged or documented as participating. If your note says "patient attended but did not participate," expect a denial if the claim is reviewed.
Medication-Assisted Treatment and Medication Management Codes
MAT billing is where things get complicated fast. The codes depend on the medication, the setting, the clinician type, and whether you're billing for the medication itself or the management service.
99213 and 99214 with modifier HF are the E&M codes for outpatient office visits when the primary purpose is substance use disorder medication management. 99213 covers a straightforward visit (typically 20-29 minutes), while 99214 covers a more complex visit (30-39 minutes). Modifier HF signals to the payer that this is a substance use disorder service. Without the HF modifier, some payers will deny the claim or reimburse at a lower rate. These codes require a physician, NP, or PA.
H0020 is the HCPCS code for alcohol and drug services, specifically methadone administration and service. It's used by opioid treatment programs (OTPs) for the daily methadone dose and associated brief counseling. This is typically a bundled service code covering both the medication and the observation period. Documentation must comply with 42 CFR Part 8 regulations, which govern OTP operations including medication management codes and bundled payment structures.
T1012 covers alcohol and drug screening and brief intervention services. It's used in non-specialty settings (primary care, emergency departments) when a provider conducts screening and provides a brief counseling intervention. Medicaid and some commercial payers recognize this code. For commercial insurance, use 99408 (15-30 minutes) or 99409 (greater than 30 minutes). For Medicare, use G0396 or G0397. The SAMHSA SBIRT coding guidance breaks down the time thresholds and documentation requirements.
G-codes for OTP bundled payments: CMS introduced G2067-G2080 for opioid treatment program bundled payment services. These codes cover intake, periodic assessments, medication dispensing, counseling, and toxicology testing in a single bundled payment. They're only used by certified OTPs billing Medicare. If you're billing Medicaid or commercial payers, you'll typically use H0020 or individual service codes instead.
The most common MAT billing mistake: billing both a 99214 with HF modifier and a separate therapy code (like 90834) on the same date of service without a modifier to indicate they're separate services. Use modifier 25 on the E&M code if both services are medically necessary and separately documented.
HCPCS H-Codes for IOP, PHP, and Residential Treatment
HCPCS H-codes are the workhorses of intensive outpatient and residential billing. They're primarily used by Medicaid, but many commercial payers have adopted them in their SUD carve-out contracts. Understanding which code corresponds to which level of care is essential for accurate billing.
H0015 is alcohol and drug services for intensive outpatient treatment. This is your IOP code. It's typically billed per day or per session depending on payer policy. Some payers reimburse H0015 as a per-diem rate covering all services provided that day (groups, individual sessions, case management). Others allow you to bill H0015 alongside individual therapy codes. Understanding how your specific payers handle H0015 is critical to maximizing revenue without triggering bundling denials.
H0017 covers behavioral health services in a residential setting, per diem. This is your residential treatment per-diem code. It includes room, board, counseling, medication management, and other services provided as part of the residential program. Typical Medicaid reimbursement ranges from $150 to $400 per day depending on state rates and level of care. Documentation must support medical necessity for residential level of care based on ASAM criteria.
H0018 is behavioral health services, short-term residential. This code is used in some states for lower-intensity residential programs or transitional residential settings. Reimbursement is typically lower than H0017. Check your state Medicaid billing manual for specific definitions and requirements.
H0019 covers behavioral health services in a halfway house, per diem. This is for recovery housing or sober living environments that provide some clinical services. Many commercial payers do not cover H0019 at all, and Medicaid coverage varies widely by state. If you're operating a recovery residence, verify coverage before assuming this code is billable.
The biggest H-code denial risk: billing H0015 for a patient who doesn't meet the minimum clinical contact hours for IOP. Most payers define IOP as 9+ hours per week of structured programming. If your patient only attended 4 hours that week, the claim will likely be denied or downcoded to a lower level of care.
Modifiers That Make or Break Addiction Treatment Claims
Modifiers are the secret language of addiction treatment billing. Use the right one, and your claim sails through. Leave it off, and you get an automatic denial even if the service was medically necessary and perfectly documented.
Modifier HF signals substance abuse program services. It's required by many payers when billing E&M codes (99213, 99214) or therapy codes in the context of substance use disorder treatment. Without HF, some payers will deny the claim as not meeting SUD benefit criteria.
Modifier HH indicates integrated mental health and substance abuse program services. Use this when you're providing co-occurring disorder treatment that addresses both mental health and SUD in the same session. Some payers reimburse HH services at a higher rate than HF alone.
Modifier HN signals a behavioral health program. It's less commonly used than HF or HH but may be required by specific payers for certain behavioral health services that don't fit neatly into mental health or SUD categories.
Modifier HA indicates a child/adolescent program. If you're billing for adolescent SUD services, some payers require HA to route the claim to the correct benefit category and reimbursement rate.
Modifiers U1-U9 are Medicaid-specific modifiers used by some states to indicate different levels of service intensity, clinician credentials, or program types. For example, U1 might indicate a service provided by a licensed clinician, while U3 might indicate a service provided by a certified peer recovery specialist. These vary by state; check your Medicaid billing manual.
Modifier 95 or GT indicates telehealth services delivered via synchronous audio-video technology. As of 2026, most payers accept either 95 or GT, but some have a preference. Medicare prefers 95; some Medicaid programs still use GT. When in doubt, check the payer's telehealth billing policy.
Modifier 25 is critical when billing an E&M code and a procedure code on the same date of service. For example, if you bill 99214 with HF for medication management and 90834 for individual therapy on the same day, add modifier 25 to the E&M code to signal that they're separate, medically necessary services. Without it, the payer will bundle them and only pay for one.
The most common modifier mistake: using HF on a claim for a patient whose primary diagnosis is a mental health condition rather than a substance use disorder. If the primary ICD-10 code is depression (F33.1) and the SUD is secondary, some payers will deny an HF-modified claim. Diagnosis coding order matters when you're using SUD-specific modifiers.
Lab and Toxicology Testing Codes
Urine drug screens and other toxicology testing are essential clinical tools and billable services, but they're also heavily audited. The codes changed significantly in recent years, and billing the outdated codes is a fast track to denials.
80305-80307 are the CPT codes for presumptive drug testing (immunoassay). 80305 is for any number of drug classes using an instrument-read device. 80306 and 80307 are for specific configurations of read methods. Most treatment centers use 80305 for point-of-care cups. Reimbursement ranges from $10 to $40 depending on payer.
G0477-G0483 are the HCPCS codes for definitive drug testing using quantitative methods (typically lab-based testing like LC/MS). These codes specify the number of drug classes tested. They're used when you need to confirm a presumptive positive or test for specific drugs not covered by immunoassay panels. Reimbursement is significantly higher than presumptive testing but requires specific medical necessity documentation.
The biggest toxicology billing mistake: billing definitive testing without a medically necessary reason documented in the chart. Payers expect definitive testing to be used for confirmation of unexpected results, monitoring compliance in high-risk patients, or clinical situations where precise quantification is needed. Routine weekly definitive testing for every patient will trigger audits and recoupment demands.
Documentation Standards That Defend Your Claims in UR Review
You can bill the perfect code with the perfect modifier, but if your documentation doesn't support medical necessity and level of service, you'll lose the appeal. Here's what utilization review teams actually look for.
Time documentation: For time-based codes (90832, 90834, 90837, 99408, 99409), you need start and stop times or total duration documented in the note. "Approximately 45 minutes" is not sufficient for many payers. "Session conducted from 10:00 AM to 10:47 AM, total duration 47 minutes" is defensible.
Medical necessity: Every note must connect the service provided to the patient's diagnosis and treatment plan. "Patient attended group therapy" is insufficient. "Patient participated in relapse prevention group, identified triggers related to F11.20 opioid use disorder, practiced coping skills, demonstrated understanding of concepts" supports medical necessity.
Level of care justification: When billing IOP (H0015) or residential codes (H0017), your clinical documentation must support that level of care based on ASAM criteria. If a payer reviews the chart and sees that the patient has stable housing, no acute withdrawal risk, and good family support, they'll question why residential treatment was medically necessary instead of outpatient.
Credential documentation: Make sure your billing system has the correct credentials for each clinician. If you bill 90837 under an NPI that's registered as an unlicensed intern, the claim will be denied. If you're billing MAT codes under a nurse practitioner, verify that your state allows NPs to prescribe buprenorphine and that the NP has the required waiver (or that the waiver requirement has been eliminated, as of recent federal changes).
For treatment centers navigating complex billing requirements across multiple states and payers, having an EHR system that supports compliant documentation is essential to defending claims and avoiding recoupment.
State-Specific Variations and Payer Quirks
Every state Medicaid program has its own billing manual, and commercial payers layer their own policies on top of standard CPT and HCPCS guidelines. Here are the variations that cause the most confusion.
IOP billing structure: Some states allow you to bill H0015 plus individual therapy codes (90834, 90837) on the same day. Others bundle all IOP services into a single H0015 per-diem rate. Indiana, for example, has specific rules about what can and cannot be billed separately during an IOP episode. If you're operating in Indiana, understanding the MCE-specific billing rules is critical to avoiding denials.
Modifier requirements: Some state Medicaid programs require U-modifiers for every claim. Others use H-modifiers. Some commercial payers don't recognize H-modifiers at all and want you to use standard CPT modifiers only. You need a payer-specific billing matrix to track these requirements.
Telehealth policies: As of 2026, telehealth flexibilities vary dramatically by payer and state. Some states extended COVID-era telehealth parity laws permanently. Others reverted to pre-pandemic policies that limit or exclude telehealth for SUD services. Check your state's behavioral health authority and each payer's telehealth billing policy before assuming a telehealth claim will be paid.
Prior authorization requirements: Some payers require prior authorization for every IOP admission. Others have authorization thresholds based on length of stay or number of sessions. Billing without obtaining required authorization is the fastest way to get a denial that can't be appealed.
How ForwardCare Helps Treatment Centers Get Paid Correctly
You didn't open a treatment center to become a billing expert. You did it to save lives. But if your billing operation is leaving 15-25% of your revenue on the table because of coding errors, missing modifiers, or documentation gaps, you can't sustain the mission.
ForwardCare provides MSO and revenue cycle management services specifically designed for addiction treatment centers. We handle credentialing, billing, collections, denial management, and compliance so you can focus on clinical care. Our team knows the difference between H0015 per-diem and fee-for-service billing structures. We know which payers bundle MAT codes and which ones allow separate billing. We know how to appeal denials with the documentation that actually wins.
If you're spending more time fighting with payers than treating patients, or if you suspect your billing team is missing revenue opportunities because they don't know the latest code updates, let's talk. We'll review your current billing operation, identify the gaps, and show you exactly how much revenue you're leaving on the table.
Contact ForwardCare today to schedule a complimentary billing assessment and learn how we help treatment centers across the Midwest maximize revenue while maintaining full compliance with payer requirements and federal regulations.
