What is ICD-10 code F43.21?

F43.21 is the ICD-10-CM diagnosis code for Adjustment disorder with depressed mood. A condition where a person develops depressed mood and emotional distress in response to a specific identifiable life stressor or change. It belongs to the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99). F43.21 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. F43.21 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. F43.21 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. F43.21 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.

What is the V28 vs V24 difference for F43.21?

F43.21 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards F43.21 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

What should coders know when reporting F43.21?

Document the specific stressor (job loss, relationship change, relocation, etc.) that triggered the adjustment Confirm that depressed mood is the predominant symptom and that symptoms began within 3 months of the stressor

F43.21: Adjustment disorder with depressed mood —

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 lookupF43.21Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Mental, Behavioral and Neurodevelopmental disorders (F01-F99) / Anxiety, dissociative, stress-related, somatoform and other nonpsychotic mental disorders (F40-F48)

F43.21

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

Adjustment disorder with depressed mood

A condition where a person develops depressed mood and emotional distress in response to a specific identifiable life stressor or change.

Buddy Insight

Adjustment disorder with depressed mood represents a reactive depression developing within 3 months of an identifiable stressor.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Not risk-adjusted for this model/period.

RAF 0

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Not risk-adjusted for this model/period.

RAF 0

RXHCC

Mapped

HCC 133

Personality Disorders, Anxiet...

RAF 0.0

Code Trumping

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Code Book Path

Official

F43Reaction to severe stress, and adjustment disorders

F43.2Adjustment disorders

F43.21Adjustment disorder with depressed mood

Inclusion Terms

Official

Culture shock
Grief reaction
Hospitalism in children

Excludes 2

Official

separation anxiety disorder of childhood (F93.0)

Related Child Codes

Official

F43.20Adjustment disorder, unspecified

F43.22Adjustment disorder with anxiety

F43.23Adjustment disorder with mixed anxiety and depressed mood

F43.24Adjustment disorder with disturbance of conduct

F43.25Adjustment disorder with mixed disturbance of emotions and conduct

Includes

Official

ICD-10-CM does not list Includes notes for F43.21 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for F43.21 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for F43.21 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for F43.21 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for F43.21 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Identifiable stressor documented

Depressed mood as the predominant symptom

Symptom onset within 3 months of the stressor

Symptoms do not meet full criteria for major depressive disorder

MEAT Support

HCC Buddy guidance

Identifiable stressor documented

Depressed mood as the predominant symptom

Symptom onset within 3 months of the stressor

Symptoms do not meet full criteria for major depressive disorder

Audit Caution

HCC Buddy guidance

Using adjustment disorder with depressed mood when the patient actually meets criteria for MDD — adjustment disorder is less severe by definition

Not identifying the precipitating stressor — adjustment disorder requires a documented stressor

Continuing to code adjustment disorder when symptoms have persisted beyond 6 months after stressor resolution — reassess for other mood disorders

Confusing normal grief with adjustment disorder with depressed mood

Common Mistakes

HCC Buddy guidance

F32.0 (Major depressive disorder, single episode, mild) — MDD has specific diagnostic criteria (5+ symptoms, 2+ weeks); adjustment disorder with depressed mood is reactive and does not meet full MDD criteria

F43.23 (Adjustment disorder with mixed anxiety and depressed mood) — Use F43.21 when depressed mood predominates without significant anxiety

F43.20 (Adjustment disorder, unspecified) — Use the specific subtype F43.21 when depressed mood is documented

F34.1 (Dysthymic disorder) — Dysthymia is chronic (2+ years); adjustment disorder is time-limited

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is F43.21 an HCC code?

No. F43.21 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.

HCC Category Mapping

RxHCCHCC 133, Personality Disorders, Anxiety, and Other Specified Mental Disorders

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.

MEAT Criteria for F43.21

For F43.21to 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 F43.21 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

F43.21 is the ICD-10-CM diagnosis code for adjustment disorder with depressed mood. A condition where a person develops depressed mood and emotional distress in response to a specific identifiable life stressor or change. F43.21 sits in the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99), within the section covering anxiety, dissociative, stress-related, somatoform and other nonpsychotic mental disorders (f40-f48).

F43.21 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.

F43.21 does not map to any HCC under V24 or V28. No ESRD mapping. RxHCC maps to RxHCC 133 at 0.0 weight. Non-risk-adjusting diagnosis. Coders reviewing F43.21 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 F43.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document the specific stressor (job loss, relationship change, relocation, etc.) that triggered the adjustment
•Confirm that depressed mood is the predominant symptom and that symptoms began within 3 months of the stressor

Clinical Significance

Adjustment disorder with depressed mood represents a reactive depression developing within 3 months of an identifiable stressor. It is clinically important to distinguish this from major depressive disorder, as adjustment disorders are expected to be time-limited and resolve once the stressor or its consequences end. This distinction affects treatment planning and prognosis.

Documentation Requirements

✓Identifiable stressor documented
✓Depressed mood as the predominant symptom
✓Symptom onset within 3 months of the stressor
✓Symptoms do not meet full criteria for major depressive disorder
✓Functional impairment or marked distress beyond what would be expected
✓Current treatment plan (supportive therapy, brief psychotherapy, possibly short-term medication)

Commonly Confused Codes

•F32.0 (Major depressive disorder, single episode, mild): MDD has specific diagnostic criteria (5+ symptoms, 2+ weeks); adjustment disorder with depressed mood is reactive and does not meet full MDD criteria
•F43.23 (Adjustment disorder with mixed anxiety and depressed mood): Use F43.21 when depressed mood predominates without significant anxiety
•F43.20 (Adjustment disorder, unspecified): Use the specific subtype F43.21 when depressed mood is documented
•F34.1 (Dysthymic disorder): Dysthymia is chronic (2+ years); adjustment disorder is time-limited