F09 — Unspecified mental disorder due to known physiological condition
Is F09 billable?
Yes, but F09 is an unspecified code. F09 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, F09 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting F09.
F09 at a glance
| Code | F09 |
|---|---|
| Description | Unspecified mental disorder due to known physiological condition |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does F09 group to?
F09 sits in MDC 19 and helps define the logic of 1 MS-DRG (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 884Organic Disturbances and Intellectual Disabilitymedical
How is F09 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to F09. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Deficiency, deficient › cognitive
- Disorder › cognitive (of)
- Organic › brain syndrome
- Organic › mental disorder
- Organic › psychosis
- Psychosis, psychotic › organic
- Psychosis, psychotic › symptomatic
- Syndrome › brain
- Disease, diseased › mental › organic
- Disorder › cognitive › due togeneral medical condition (of)
- Disorder › mental › organic or symptomatic (of)
- Syndrome › brain › with psychosis, psychotic reaction
Excludes1 — never code together
The conditions below can never be reported together with F09 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Code first
The underlying condition below must be sequenced before F09. F09 describes a manifestation and cannot be the principal or first-listed diagnosis.
- the underlying physiological condition
Inclusion terms
Alternative wording in documentation that is classified to F09.
- Mental disorder NOS due to known physiological condition
- Organic brain syndrome NOS
- Organic mental disorder NOS
- Organic psychosis NOS
- Symptomatic psychosis NOS
Excludes2 — not included here — inherited from Chapter 5
The conditions below are not part of F09, but a patient may have both at the same time. When documentation supports it, F09 and the excluded code may both be reported.
- symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)
How long has F09 existed?
F09 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with F09?
ICD-10-CM declares these codes mutually exclusive with F09 — exactly one of each pair can be correct for a given encounter.