ICD-10-CM code F99 describes mental disorder, not otherwise specified. Catch-all mental health diagnosis when no other code applies; prefer specificity. It is a billable, specific code valid for claim submission. It is grouped under the “Other Mental Health Diagnoses” section of the mental, behavioral, and neurodevelopmental disorders chapter.
When to use F99
This catch-all is reserved for mental health diagnoses that do not fit a more specific category. Prefer a specific code whenever the documentation supports one. For F99 specifically, catch-all mental health diagnosis when no other code applies; prefer specificity.
Documentation & billing
Document the clinical basis for the diagnosis. Reserve unspecified codes for the rare case in which no more specific code applies.
Common pitfalls
- Defaulting to an unspecified mental disorder (F99) when a specific code is available.
- Using catch-all codes to avoid documenting clinical specifics.
Common search terms for F99
Clinicians often look up F99 using plain-language terms. This code maps to:
Frequently asked questions
What is ICD-10-CM code F99?
Mental disorder, not otherwise specified. Catch-all mental health diagnosis when no other code applies; prefer specificity.
Is F99 a billable ICD-10-CM code?
Yes. F99 (Mental disorder, not otherwise specified) is a billable, specific ICD-10-CM code that can be reported on a claim. Confirm the current official descriptor against the CDC code set and your payer’s policies before submitting.
What should I document to support F99?
Document the clinical basis for the diagnosis. Reserve unspecified codes for the rare case in which no more specific code applies.