C4A.0 — Merkel cell carcinoma of lip

Billable

Is C4A.0 billable?

Yes — C4A.0 is billable for FY2027. C4A.0 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. C4A.0 may be submitted for encounters from October 1, 2026 through September 30, 2027.

C4A.0 at a glance

Code	C4A.0
Description	Merkel cell carcinoma of lip
Billable	Yes
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

Which MS-DRGs does C4A.0 group to?

C4A.0 sits in MDC 09 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.

595Major Skin Disorders with MCCmedical
596Major Skin Disorders without MCCmedical

How is C4A.0 listed in the Alphabetic Index?

These are the routes through the Alphabetic Index that lead to C4A.0. They show the wording a clinician may have documented, which often differs from the Tabular description.

Carcinoma › Merkel cell › lip (malignant)

Excludes1 — never code together

The conditions below can never be reported together with C4A.0 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.

malignant neoplasm of vermilion border of lip (C00.0-C00.2)

How long has C4A.0 existed?

C4A.0 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.

Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.

Which codes are confused with C4A.0?

ICD-10-CM declares these codes mutually exclusive with C4A.0 — exactly one of each pair can be correct for a given encounter.