ICD-10-CM 2027 diagnosis code

A42Actinomycosis

Not billable — use a more specific code

A42 is a header code, so it can't be reported by itself. Choose one of the 6 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About A42

A42 is the ICD-10-CM diagnosis code for actinomycosis. It belongs to block A30-A49 (other bacterial diseases) and chapter 1 (certain infectious and parasitic diseases). It is a header code, so it can't be reported by itself; one of its 6 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: A42.0 (actinomycosis), A42.1 (actinomycosis), A42.2 (actinomycosis), A42.7 (sepsis), A42.8 (actinomycosis) and A42.9 (unspecified).

Don't report A42 together with the conditions in its Excludes1 note: actinomycetoma (B47.1).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under A42

Coding notes

Excludes1Not coded here — never report together with this code

actinomycetoma (B47.1)

Notes that apply from higher levels

Instructions written at a parent level also apply to A42.

Broader instructions also apply from Chapter 1: Certain infectious and parasitic diseases.

Code history

2016
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2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about A42

Is A42 billable?: No. A42 is a header code. Report one of its more specific subcodes instead.