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F99

✓ Billable

Mental disorder, not otherwise specified

Mental, Behavioral and Neurodevelopmental disorders (F01-F99)

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Also Known As

Mental illness NOS

❌ Excludes1

direct

Cannot be coded with F99

  • • unspecified mental disorder due to known physiological condition (F09)

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Code Information

CodeF99
BillableYes
CategoryMental, Behavioral and Neurodevelopmental disorders (F01-F99)
Excludes11 rule(s)
Excludes20 note(s)

Data Source

CMS ICD-10-CM 2026 Tabular List

Updated October 1, 2025 (FY2026)