F09 — Unspecified mental disorder due to known physiological condition
F09 is a billable, specific ICD-10-CM code for unspecified mental disorder due to known physiological condition. It is valid for submission on a claim.
Excludes1 — never code together
These conditions cannot occur together. Billing both on the same encounter is a denial.
Code first
The underlying condition must be sequenced before this code.
- the underlying physiological condition
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Mental disorder NOS due to known physiological condition
- Organic brain syndrome NOS
- Organic mental disorder NOS
- Organic psychosis NOS
- Symptomatic psychosis NOS
Other codes that can never be billed with F09
These codes carry an Excludes1 note pointing at F09. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading F09 alone.
Risk adjustment
F09 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
F09 is named in 10 Medicare coverage policies — 9 listing it as supporting medical necessity, and 1 listing it as NOT covered. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A52434Health and Behavior Assessment/Intervention – Medical Policy Articlenot covered
- A56612Billing and Coding: CT of the Head
- A56937Billing and Coding: Psychiatry and Psychology Services
- A56937Billing and Coding: Psychiatry and Psychology Services
How F09 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to F09.
- Deficiency, deficient›cognitive
- Disorder›cognitive
- Organic›brain syndrome
- Organic›mental disorder
- Organic›psychosis
- Psychosis, psychotic›organic
- Psychosis, psychotic›symptomatic
- Syndrome›brain(nonpsychotic)
- Disease, diseased›mental›organic
- Disorder›cognitive›due to general medical condition(secondary to)
- Disorder›mental›organic or symptomatic
- Syndrome›brain›organic
Questions about F09
- Is F09 a billable ICD-10-CM code?
- Yes. F09 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does F09 sit in the tabular list?
- Mental, Behavioral and Neurodevelopmental disorders (F01-F99), in the block Mental disorders due to known physiological conditions (F01-F09).
- What cannot be coded together with F09?
- F09 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.