C00.5 ICD-10-CM Code: Malignant neoplasm of lip, unspecified, inner aspect
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lip, oral cavity and pharynx (C00-C14)
C00.5
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMalignant neoplasm of lip, unspecified, inner aspect
Cancer of the inner lip surface when it is unclear whether it involves the upper or lower lip.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
Official- Malignant neoplasm of buccal aspect of lip, unspecified
- Malignant neoplasm of frenulum of lip, unspecified
- Malignant neoplasm of mucosa of lip, unspecified
- Malignant neoplasm of oral aspect of lip, unspecified
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for C00.5 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for C00.5 in this effective period.
Excludes 1
Official- malignant melanoma of lip (C43.0)
- Merkel cell carcinoma of lip (C4A.0)
- other and unspecified malignant neoplasm of skin of lip (C44.0-)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for C00.5 in this effective period.
Use Additional
Official- code to identify:
- alcohol abuse and dependence (F10.-)
- history of tobacco dependence (Z87.891)
- tobacco dependence (F17.-)
- tobacco use (Z72.0)
Code Also
OfficialICD-10-CM does not list Code Also instructions for C00.5 in this effective period.
Buddy Documentation Tip
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is C00.5 an HCC code?
No. C00.5 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- C00.5
- Description
- Malignant neoplasm of lip, unspecified, inner aspect
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
C00.5 is the ICD-10-CM diagnosis code for malignant neoplasm of lip, unspecified, inner aspect. Cancer of the inner lip surface when it is unclear whether it involves the upper or lower lip. C00.5 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of lip, oral cavity and pharynx (c00-c14).
C00.5 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Use only when the specific location (upper vs. lower inner lip) is not documented.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C00.5 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use only when the specific location (upper vs. lower inner lip) is not documented
- •Attempt to obtain clarification from the provider for more precise coding