ICD-10-CM 2027
ICD-10 code for mental aberration
From the official ICD-10-CM alphabetic index entry “Aberration › mental”. Page updated September 29, 2026.
About coding mental aberration
The ICD-10-CM code for mental aberration is F99 (Mental disorder, not otherwise specified).
Don't report F99 together with the conditions in its Excludes1 note: unspecified mental disorder due to known physiological condition (F09).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 880 (Acute Adjustment Reaction and Psychosocial Dysfunction, relative weight 0.9306), in MDC 19 (Mental Diseases and Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Don't confuse with (Excludes1 for F99)
- unspecified mental disorder due to known physiological condition (F09)
Common questions about mental aberration ICD-10 codes
What is the ICD-10 code for mental aberration?
- F99 — Mental disorder, not otherwise specified.
Is F99 billable?
- Yes. F99 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can F99 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict F99 as a principal diagnosis.
Is F99 a CC or MCC?
- No. F99 is neither a CC nor an MCC under MS-DRG v44.0.