C03.0 ICD-10-CM Code: Malignant neoplasm of upper gum
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)
C03.0
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMalignant neoplasm of upper gum
Cancer of the upper gum tissue, the soft tissue covering the upper jaw bone.
Buddy Insight
Malignant neoplasm of the upper gum is a relatively uncommon oral cavity cancer that carries significant risk adjustment weight.
CMS-HCC V28
MappedHCC 21
RAF 0.545
CMS-HCC V24
MappedHCC 11
RAF 0.306
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 11
RAF 0.0
RXHCC
MappedHCC 22
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for C03.0 in this effective period.
Excludes 2
Official- malignant odontogenic neoplasms (C41.0-C41.1)
Related Child Codes
Includes
Official- malignant neoplasm of alveolar (ridge) mucosa
- malignant neoplasm of gingiva
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for C03.0 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for C03.0 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 C03.0 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is C03.0 an HCC code?
Yes. C03.0 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model (and Colorectal, Bladder, and Other Cancers under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for C03.0
For C03.0to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C03.0 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
C03.0 is the ICD-10-CM diagnosis code for malignant neoplasm of upper gum. Cancer of the upper gum tissue, the soft tissue covering the upper jaw bone. C03.0 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).
Under the CMS-HCC V28 risk adjustment model, C03.0 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors (HCC 21) with a community, non-dual, aged base RAF weight of 0.545. Under the older CMS-HCC V24 model, C03.0 maps to Colorectal, Bladder, and Other Cancers (HCC 11) with a community, non-dual, aged base RAF weight of 0.306. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Upper gum refers to the gingiva of the maxilla; distinguish from lower gum (C03.1). Because C03.0 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C03.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Upper gum refers to the gingiva of the maxilla; distinguish from lower gum (C03.1)
- •Verify whether the lesion originates in gum tissue versus underlying bone or other structures
Clinical Significance
Malignant neoplasm of the upper gum is a relatively uncommon oral cavity cancer that carries significant risk adjustment weight. Early detection is critical as gingival cancers can invade underlying maxillary bone, and accurate site-specific coding ensures appropriate resource allocation for the complex multimodal treatment these patients require.
Documentation Requirements
- ✓Histological type confirmed by biopsy (squamous cell carcinoma is most common)
- ✓Specific anatomical site: upper gum (maxillary gingiva) documented by provider
- ✓TNM staging including tumor size, nodal involvement, and metastatic status
- ✓Current treatment status: active treatment, surveillance, or history of
- ✓Tobacco and alcohol use history as risk factors
Commonly Confused Codes
- •C03.1 — Malignant neoplasm of lower gum; confused when documentation says 'gum cancer' without specifying upper vs lower jaw
- •C03.9 — Malignant neoplasm of gum, unspecified; should only be used when upper/lower cannot be determined from documentation
- •C41.0 — Malignant neoplasm of bones of skull/face; use when cancer originates in maxillary bone rather than gingival soft tissue
- •C05.0 — Malignant neoplasm of hard palate; adjacent structure that may be confused when tumor extends from gum to palate