Question 1

What is ICD-10 code C03?

Accepted Answer

C03 is the ICD-10-CM diagnosis code for Malignant neoplasm of gum. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C03 is a non-billable header code that organizes more specific child codes; the actual diagnosis on a claim must use one of those children. C03 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Question 2

Is C03 an HCC code?

Accepted Answer

C03 is a non-billable header code, so it cannot itself be a payment HCC. Header codes organize more specific child codes that share the same root concept; one of those children may map to a payment HCC under the CMS-HCC V28 or V24 risk adjustment model. Coders should select a child code from the C03 hierarchy that matches the documented presentation, then check that specific child for HCC status.

Question 3

Is C03 billable?

Accepted Answer

No. C03 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 C03 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 C03 map to under V28?

Accepted Answer

C03 does not map to a CMS-HCC V28 payment category. Check the current CMS-HCC V28 model file for payment year 2026 rather than an older V24 tip sheet.

Question 5

What does C03 pay in RAF?

Accepted Answer

C03 has no separately stated V28 community RAF weight. If it is not a V28 payment HCC, it adds nothing to a community RAF score.

Question 6

What documentation supports C03?

Accepted Answer

C03 is not a CMS-HCC payment code, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

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C03

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What This Code Means

Includes

Excludes 2, Not included here, may code separately

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Code Hierarchy

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C03 ICD-10-CM Code: Malignant neoplasm of gum