ICD-10 for therapists

F43.21 — Adjustment disorder with depressed mood

Reviewed by Albert Wong, PhD, Clinical Psychologist · Updated July 29, 2026

Clinically significant low mood developing within three months of an identifiable stressor, out of proportion to the stressor or functionally impairing, without meeting full MDD criteria.

Code: F43.21 (ICD-10-CM)
Common CPT pairings: 90791 · 90834 · 90837

Clinical picture

Onset within three months of a stressor; symptoms should resolve within six months of the stressor (or its consequences) ending.
The most common intake diagnosis in many outpatient practices — and the correct one when depression criteria are not fully met.
If full MDD criteria are met, code the MDD family instead; adjustment disorder is not a 'lighter MDD.'

Documentation tips

Name the stressor and the onset timeline in the chart; this pairing is the diagnosis's backbone.
Reassess by six months: persistence suggests re-diagnosis (MDD, GAD, PDD) rather than extending the adjustment frame.

Billing notes

Broadly reimbursed; some plans apply shorter initial authorization windows to adjustment codes, so track reauthorization timing.

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This reference summarizes ICD-10-CM coding conventions and common billing practice for licensed clinicians. It is not medical, legal, or payer-specific billing advice; diagnosis requires clinical evaluation, and payer policies vary. Verify codes against the current ICD-10-CM release.