F91.9 ICD-10-CM Code: Conduct disorder, unspecified
F91.9 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · HCC Buddy coding tools
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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)
F91.9
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceConduct disorder, unspecified
A behavioral disorder in children characterized by persistent patterns of violating others' rights, breaking rules, and engaging in aggressive or destructive behavior, without a more specific diagnosis identified.
Buddy Insight
Unspecified conduct disorder is used when the provider documents a conduct disorder diagnosis without specifying the subtype or onset type.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
MappedHCC 133
RAF 0.035
Code Book Path
Inclusion Terms
Official- Behavioral disorder NOS
- Conduct disorder NOS
- Disruptive behavior disorder NOS
- Disruptive disorder NOS
Excludes 2
Official- conduct problems associated with attention-deficit hyperactivity disorder (F90.-)
- mood [affective] disorders (F30-F39)
- pervasive developmental disorders (F84.-)
- schizophrenia (F20.-)
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for F91.9 in this effective period.
Excludes 1
Official- antisocial behavior (Z72.81-)
- antisocial personality disorder (F60.2)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for F91.9 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for F91.9 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for F91.9 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 F91.9 an HCC code?
F91.9 is not in the CMS-HCC V28 or V24 community payment model, but it does map to Personality Disorders, Anxiety, and Other Specified Mental Disorders under the Part D RxHCC model.
- Code
- F91.9
- Description
- Conduct disorder, unspecified
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so 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 segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
Work F91.9 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for F91.9
For F91.9 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.
- 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
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed F91.9 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
F91.9 is the ICD-10-CM diagnosis code for conduct disorder, unspecified. A behavioral disorder in children characterized by persistent patterns of violating others' rights, breaking rules, and engaging in aggressive or destructive behavior, without a more specific diagnosis identified. F91.9 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).
F91.9 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
This code does not map to a CMS-HCC V28 payment category. Capture depends on documentation that supports the diagnosis; verify the HCC assignment against the current CMS mapping for the applicable payment year. Coders reviewing F91.9 should check whether additional documentation would support a more specific child code in the same hierarchy that does map to a payment HCC, capturing the correct specificity is the highest-impact RAF improvement available within accurate coding.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for F91.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the conduct disorder cannot be classified as childhood-onset, adolescent-onset, or unspecified onset type
- •Document the specific behaviors and age of onset to support medical necessity and consider if a more specific F91 code applies
Clinical Significance
Unspecified conduct disorder is used when the provider documents a conduct disorder diagnosis without specifying the subtype or onset type. While clinically acceptable, subtype specification (childhood-onset vs. adolescent-onset) has important prognostic implications. Conduct disorders are associated with significant long-term risks including antisocial personality disorder, substance use disorders, and criminal behavior.
Documentation Requirements
- ✓Provider documentation of conduct disorder diagnosis
- ✓Evidence of persistent behavioral pattern violating others' rights or societal norms
- ✓Query opportunity — attempt to determine age of onset to specify childhood vs. adolescent-onset type
- ✓Functional impairment documentation
- ✓Treatment plan addressing the conduct disturbance
Commonly Confused Codes
- •F91.1: Conduct disorder, childhood-onset type; use when onset before age 10 is documented
- •F91.2: Conduct disorder, adolescent-onset type; use when onset in adolescence is documented
- •F91.3: Oppositional defiant disorder; ODD is less severe than conduct disorder
- •Z72.810: Child and adolescent antisocial behavior; isolated antisocial acts do not constitute conduct disorder