F99 – Mental disorder, not otherwise specified
ICD-10-CM 2027 diagnosis code · Unspecified mental disorder (F99)
ICD-10-CM code
F99
- Code
F99(claims format:F99)- Description
- Mental disorder, not otherwise specified
- Billable
- Yes – valid for HIPAA-covered transactions
- Valid for
- Dates of service October 1, 2026 – September 30, 2027 (FY2027)
- Chapter
- 5. Mental, Behavioral and Neurodevelopmental disorders (F01-F99)
- Block
- F99 Unspecified mental disorder (F99)
Notes for F99
Applicable to:
- Mental illness NOS
Excludes1 (not coded here):
- unspecified mental disorder due to known physiological condition (F09)
Index terms for F99
Entries in the ICD-10-CM alphabetic index that lead to this code:
Frequently asked questions
What is ICD-10 code F99?
F99 is the ICD-10-CM code for mental disorder, not otherwise specified, in the block F99 (Unspecified mental disorder (F99)).
Is F99 a billable code?
Yes. F99 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.
Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.