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F43.21 · Billable

2026 ICD-10-CM Diagnosis Code F43.21

Adjustment disorder with depressed mood

About F43.21

Code

F43.21

Description

Adjustment disorder with depressed mood

Billable

Yes — billable on its own

Parent code

F43 (Reaction to severe stress, and adjustment disorders)

Category

F40-F49 — Anxiety, dissociative, stress-related, somatoform and other nonpsychotic mental disorders

Set

ICD-10-CM 2026

Clinical context

Inherited from F43 (Reaction to severe stress, and adjustment disorders)

F43 covers conditions that arise as a direct response to an identifiable stressor — including acute stress reaction (F43.0), post-traumatic stress disorder (F43.10/F43.11/F43.12), and adjustment disorders (F43.20–F43.29). PTSD is one of the most billed F-codes in trauma-focused practice.

Code details

Code attributes

  • Non-billable/Non-specific code

Coding rules

  • Document the stressor — F43 codes require an identifiable precipitating stressor. Document the event, its proximity to symptom onset, and the patient's appraisal.
  • PTSD subtype matters — F43.10 (unspecified), F43.11 (acute), F43.12 (chronic) — chronicity changes the code.
  • Adjustment disorder is specific — F43.21 (depressed mood), F43.22 (anxiety), F43.23 (mixed) — match the predominant clinical feature.

Sources

  • Centers for Medicare & Medicaid Services — 2026 ICD-10-CM
  • AAPC — ICD-10-CM Code Lookup
  • CDC — ICD-10-CM Official Guidelines for Coding and Reporting

This reference is provided for billing and documentation guidance only. It is not medical advice. For clinical decision-making, consult the current CMS ICD-10-CM Official Guidelines for Coding and Reporting, and verify code applicability against the patient's documented clinical findings.

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