F84.0 vs F84.2
F84.0 and F84.2 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on F84.2
Autistic disorder (F84.0)
F84.0
Autistic disorder
Billable
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F80-F89
Use when the record says
- Autism spectrum disorder
- Infantile autism
- Infantile psychosis
- Kanner's syndrome
Indexed under
- Autism, autistic (childhood) (infantile)
- Autism, autistic › spectrum disorder (childhood) (infantile)
- Disorder › autistic (of)
- Disorder › autism spectrum (of)
- Psychosis, psychotic › childhood
F84.2
Rett's syndrome
Billable
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F80-F89
Indexed under
- Rett's disease or syndrome
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