Excludes1 pair
F29 vs F99
F29 and F99 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on F29
mental disorder NOS (F99)
F29
Unspecified psychosis not due to a substance or known physiological condition
BillableUnspecified
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F20-F29
Use when the record says
- Psychosis NOS
- Unspecified schizophrenia spectrum and other psychotic disorder
Indexed under
- Psychosis, psychotic
- Disorder › schizophrenia spectrum and other psychotic disorder
- Psychosis, psychotic › confusional
- Psychosis, psychotic › nonorganic
- Schizophrenia, schizophrenic › spectrum and other psychotic disorder
F99
Mental disorder, not otherwise specified
Billable
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F99
Use when the record says
- Mental illness NOS
Indexed under
- Psychiatric disorder or problem
- Situation, psychiatric
- Aberration › mental
- Disease, diseased › mental
- Disease, diseased › psychiatric
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027