What is ICD-10 code F91.1?

F91.1 is the ICD-10-CM diagnosis code for Conduct disorder, childhood-onset type. A behavioral disorder that begins in childhood (typically before age 10) characterized by persistent rule-breaking, aggression, and violation of others' rights across multiple settings. F91.1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. F91.1 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. F91.1 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. F91.1 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does F91.1 map to under V28?

F91.1 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

What RAF reference is published for F91.1?

F91.1 has no V28 reference coefficient because the final FY2026 source verifies no payable V28 mapping.

What is the V28 vs V24 difference for F91.1?

F91.1 has verified no payable V28 mapping in the final FY2026 source. Select a historical effective period before making any V24 comparison.

What documentation supports F91.1?

Verify onset before age 10 and document symptoms present in home, school, and/or community settings Distinguish from adolescent-onset type (F91.2) by confirming early childhood onset F91.1 is not a CMS-HCC V28 payment code in the verified current source, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

2026 ICD-10-CM F91.1: Conduct disorder, childhood-onset type

F91.1 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupF91.1

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Mental, Behavioral and Neurodevelopmental disorders (F01-F99) / Behavioral and emotional disorders with onset usually occurring in childhood and adolescence (F90-F98)

F91.1

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Conduct disorder, childhood-onset type

A behavioral disorder that begins in childhood (typically before age 10) characterized by persistent rule-breaking, aggression, and violation of others' rights across multiple settings.

Buddy Insight

Childhood-onset conduct disorder is defined by the presence of at least one conduct disorder symptom prior to age 10 years.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ESRD/PACE

N/A

—

Not risk-adjusted for this model/period.

Not mapped

RXHCC

Mapped

HCC 133

Anxiety and Other Psychiatric...

Code-level coefficient reference

Code Book Path

Official

F91Conduct disorders F91.1Conduct disorder, childhood-onset type

Inclusion Terms

Official

Unsocialized conduct disorder
Conduct disorder, solitary aggressive type
Unsocialized aggressive disorder

Excludes 2

Official

symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)Inherited from F01-F99, F91
conduct problems associated with attention-deficit hyperactivity disorder (F90.-)Inherited from F01-F99, F91
mood [affective] disorders (F30-F39)Inherited from F01-F99, F91
pervasive developmental disorders (F84.-)Inherited from F01-F99, F91
schizophrenia (F20.-)Inherited from F01-F99, F91

Related Codes

Official

F91.0Conduct disorder confined to family context F91.2Conduct disorder, adolescent-onset type F91.3Oppositional defiant disorder F91.8Other conduct disorders F91.9Conduct disorder, unspecified

Includes

Official

disorders of psychological developmentInherited from F01-F99

Excludes 1

Official

antisocial behavior (Z72.81-)Inherited from F91
antisocial personality disorder (F60.2)Inherited from F91

Code First

Official

No Code First sequencing instructions are included in this display for F91.1. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for F91.1. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for F91.1. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation of conduct disorder with at least one characteristic symptom present before age 10

Evidence of persistent pattern of behavior violating others' rights or major age-appropriate societal norms

Documentation of the age of onset of conduct symptoms

Assessment of severity (mild, moderate, severe) based on number and seriousness of conduct problems

MEAT Support

HCC Buddy guidance

Provider documentation of conduct disorder with at least one characteristic symptom present before age 10

Evidence of persistent pattern of behavior violating others' rights or major age-appropriate societal norms

Documentation of the age of onset of conduct symptoms

Assessment of severity (mild, moderate, severe) based on number and seriousness of conduct problems

Audit Caution

HCC Buddy guidance

Confusing childhood-onset with adolescent-onset type — the critical distinction is whether symptoms appeared before age 10

Using F91.9 (unspecified) when the onset history is available to determine the correct subtype

Diagnosing conduct disorder based on a single incident rather than a persistent behavioral pattern

Not reassessing and potentially updating the diagnosis as the child ages — some may progress to antisocial PD or resolve

Common Mistakes

HCC Buddy guidance

F91.2 — Conduct disorder, adolescent-onset type; adolescent-onset has no symptoms before age 10 and generally has a better prognosis

F91.0 — Conduct disorder confined to family context; family-confined type occurs only at home

F91.3 — Oppositional defiant disorder; ODD is less severe and does not involve violation of others' basic rights

F60.2 — Antisocial personality disorder; cannot be diagnosed before age 18, but childhood-onset CD is its precursor

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is F91.1 an HCC code?

F91.1 is not in the CMS-HCC V28 or V24 community payment model. F91.1 has a separate mapping under the Part D RxHCC model (HCC 133 (Anxiety and Other Psychiatric Disorders)); the applicable result needs member context.

Code: F91.1
Description: Conduct disorder, childhood-onset type
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

RxHCCHCC 133, Anxiety and Other Psychiatric Disorders

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work F91.1 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for F91.1

For F91.1, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

Get the V28 mapping + MEAT cheat sheet

One printable reference: check representative V28 mappings and the documentation reminders your note needs. Free, no card.

Free PDF. No card. Unsubscribe anytime.

What This Code Means

F91.1 is the ICD-10-CM diagnosis code for conduct disorder, childhood-onset type. A behavioral disorder that begins in childhood (typically before age 10) characterized by persistent rule-breaking, aggression, and violation of others' rights across multiple settings. F91.1 sits in the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99), within the section covering behavioral and emotional disorders with onset usually occurring in childhood and adolescence (f90-f98).

F91.1 has no mapping under the CMS-HCC V28 or V24 community payment models. F91.1 has a separate mapping under the Part D RxHCC model (HCC 133 (Anxiety and Other Psychiatric Disorders)); the applicable result needs member context. Do not assign V28 risk adjustment value from this page; verify the applicable model and payment year before using this code for risk adjustment.

Verify onset before age 10 and document symptoms present in home, school, and/or community settings.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for F91.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify onset before age 10 and document symptoms present in home, school, and/or community settings
•Distinguish from adolescent-onset type (F91.2) by confirming early childhood onset

Clinical Significance

Childhood-onset conduct disorder is defined by the presence of at least one conduct disorder symptom prior to age 10 years. This subtype carries a worse prognosis compared to adolescent-onset type, with higher rates of physical aggression, persistent antisocial behavior into adulthood, and development of antisocial personality disorder. Early identification enables intensive intervention that may alter the trajectory toward adult antisocial outcomes.

Documentation Requirements

✓Provider documentation of conduct disorder with at least one characteristic symptom present before age 10
✓Evidence of persistent pattern of behavior violating others' rights or major age-appropriate societal norms
✓Documentation of the age of onset of conduct symptoms
✓Assessment of severity (mild, moderate, severe) based on number and seriousness of conduct problems
✓Treatment plan including evidence-based interventions (multisystemic therapy, parent management training)

Commonly Confused Codes

•F91.2: Conduct disorder, adolescent-onset type; adolescent-onset has no symptoms before age 10 and generally has a better prognosis
•F91.0: Conduct disorder confined to family context; family-confined type occurs only at home
•F91.3: Oppositional defiant disorder; ODD is less severe and does not involve violation of others' basic rights
•F60.2: Antisocial personality disorder; cannot be diagnosed before age 18, but childhood-onset CD is its precursor