ICD-10-CM 2027
ICD-10 code for atypical autism
Pervasive developmental disorder, unspecified
From the official ICD-10-CM alphabetic index entry “Autism, autistic (childhood) (infantile) › atypical”. Page updated September 29, 2026.
About coding atypical autism
The ICD-10-CM code for atypical autism is F84.9 (Pervasive developmental disorder, unspecified).
Within F84, choose F84.9 (Pervasive developmental disorder, unspecified) only when documentation doesn't support a more specific option: Autistic disorder (F84.0), Rett's syndrome (F84.2), other childhood disintegrative disorder (F84.3), Asperger's syndrome (F84.5) and other pervasive developmental disorders (F84.8).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 885 (Psychoses, relative weight 1.3901), in MDC 19 (Mental Diseases and Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about atypical autism ICD-10 codes
What is the ICD-10 code for atypical autism?
- F84.9 — Pervasive developmental disorder, unspecified.
Is F84.9 billable?
- Yes. F84.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can F84.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict F84.9 as a principal diagnosis.
Is F84.9 a CC or MCC?
- F84.9 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.