Question 1

What is ICD-10 code A42?

Accepted Answer

A42 is the ICD-10-CM diagnosis code for actinomycosis. A42 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering other bacterial diseases (a30-a49).

Header codes like A42 cannot be reported on claims directly; they organize child codes that share clinical context. Coders should select the billable child code that matches the documented presentation and then verify its current source-backed HCC mapping. Do not infer a child code or risk adjustment value from the header alone.

Question 2

Is A42 an HCC code?

Accepted Answer

A42 is a non-billable header code. Choose the billable child code supported by the documentation, then check that child's current V28 mapping.

Question 3

Is A42 billable?

Accepted Answer

No. A42 is a header (non-billable) ICD-10-CM code. Header codes sit at a higher level of the diagnosis hierarchy and exist to organize a family of more specific child codes. Per ICD-10-CM coding guidelines, a header code cannot be reported on a claim as the diagnosis, coders must select a billable child code from the A42 hierarchy that matches the highest level of specificity supported by the provider's documentation. Payers reject header codes submitted as the primary diagnosis.

Question 4

Which HCC does A42 map to under V28?

Accepted Answer

A42 is not billable. Choose a billable child code before checking its V28 mapping.

Question 5

What RAF reference is published for A42?

Accepted Answer

A42 is not billable. Choose a billable child code before checking a V28 reference coefficient.

Question 6

What is the V28 vs V24 difference for A42?

Accepted Answer

A42 is not billable. Choose a billable child code before comparing V28 with a historical V24 reference.

Question 7

What documentation supports A42?

Accepted Answer

A42 is not billable. Choose the supported billable child code before checking mapping or documentation requirements.

HCC Buddy Code Card

A42

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What This Code Means

Excludes 1, Do NOT code together

Child Codes

Code Hierarchy

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A42 ICD-10-CM Code: Actinomycosis