Mental disorder, not otherwise specified (F99) ICD-10-CM
The F99 code range covers mental disorder, not otherwise specified with 1 ICD-10-CM diagnosis codes. 1 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
- Mental illness NOS
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- unspecified mental disorder due to known physiological condition F09
Codes in the F99 Range 1 codes · 1 billable
- F99 Mental disorder, not otherwise specified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the F99 range.
Mental Disorders
Psychiatric illness or diseases manifested by breakdowns in the adaptational process expressed primarily as abnormalities of thought, feeling, and behavior producing either distress or impairment of function.
About the F99 Code Range
Mental disorders can affect thoughts, feelings, or behavior and cause distress or difficulty functioning. F99 identifies a mental disorder that is not otherwise specified. This category has no subdivisions.
Questions About This Page
How many billable codes are in the F99 range?
Of the 1 codes in this range, 1 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the F99 range classify?
The range classifies mental disorder, not otherwise specified. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
