ICD-10 Coding for ABA: Autism Diagnosis Codes and How to Use Them Correctly

The ASD ICD-10 Code Set

The transition from DSM-IV to DSM-5 in 2013 consolidated the autism spectrum under a single diagnosis (Autism Spectrum Disorder), but the ICD-10 coding system still uses the older, more granular code structure. Understanding which ICD-10 code to use for each client is essential for ABA billing.

The Primary ASD Codes

F84.0 — Childhood Autism

The most commonly used ASD code. Corresponds to what was previously called "Autistic Disorder" under DSM-IV. Use this code for clients with a DSM-5 ASD diagnosis when the diagnostic evaluation specifies Level 2 or Level 3 severity, or when the evaluator uses the term "Autistic Disorder."

F84.1 — Atypical Autism

Used for clients who do not meet the full criteria for F84.0 but have significant autistic features. Less commonly used since DSM-5 eliminated the "atypical autism" category.

F84.3 — Other Childhood Disintegrative Disorder

Rarely used. Corresponds to Childhood Disintegrative Disorder under DSM-IV.

F84.5 — Asperger's Syndrome

Still used by some evaluators and payors despite being eliminated in DSM-5. If the diagnostic evaluation uses the term "Asperger's Syndrome," use F84.5.

F84.8 — Other Pervasive Developmental Disorders

A catch-all code for ASD presentations that don't fit the other categories.

F84.9 — Pervasive Developmental Disorder, Unspecified

Used when the evaluator has diagnosed ASD but has not specified a subtype. This is the appropriate code for most DSM-5 ASD diagnoses that do not specify severity level.

Which Code to Use for DSM-5 ASD Diagnoses

DSM-5 uses a single ASD diagnosis with severity levels (Level 1, 2, or 3). The mapping to ICD-10 codes is:

Important: Use the code specified in the client's diagnostic evaluation. If the evaluator specifies F84.0, use F84.0. Do not change the diagnosis code without clinical justification.

Secondary Diagnosis Codes

Many ABA clients have secondary diagnoses that should be included on claims. Common secondary diagnoses include:

List the ASD code first (as the primary diagnosis) and secondary diagnoses after. The ASD code must be the primary diagnosis for ABA claims.

Common Diagnosis Code Errors

Error 1: Using F80.9 (speech disorder) as the primary diagnosis. ABA services are covered for ASD diagnoses, not speech disorders. If F80.9 is listed as the primary diagnosis, the claim will be denied.

Error 2: Using the wrong ASD code. If the authorization was issued with F84.0 and the claim uses F84.9, the claim may deny for diagnosis code mismatch.

Error 3: Not including the ASD code on renewal claims. Some billing systems drop the diagnosis code from renewal claims if it hasn't changed. Always verify that the ASD code is included on every claim.

Error 4: Using outdated DSM-IV codes. Codes like 299.00 (Autistic Disorder) are DSM-IV codes, not ICD-10 codes. Use the F84.x codes for all ABA billing.