C03.0 ICD-10-CM Code: Malignant neoplasm of upper gum
C03.0 maps to CMS-HCC V28 21. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools
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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
Coefficient HCC 21: 0.671 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 011
Code-level coefficient reference
ESRD/PACE
MappedHCC 11
Code-level coefficient reference
RXHCC
MappedHCC 22
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for C03.0. Check the code and parent instructions in the Code Book.
Excludes 2
Official- malignant odontogenic neoplasms (C41.0-C41.1)Inherited from C03
Related Codes
Includes
Official- malignant neoplasm of alveolar (ridge) mucosaInherited from C03
- malignant neoplasm of gingivaInherited from C03
Excludes 1
OfficialNo Excludes 1 notes are included in this display for C03.0. Check the code and parent instructions in the Code Book.
Code First
OfficialNo Code First sequencing instructions are included in this display for C03.0. Check the code and parent instructions in the Code Book.
Use Additional
Official- code to identify:Inherited from C03
- alcohol abuse and dependence (F10.-)Inherited from C03
- history of tobacco dependence (Z87.891)Inherited from C03
- tobacco dependence (F17.-)Inherited from C03
- tobacco use (Z72.0)Inherited from C03
Code Also
OfficialNo Code Also instructions are included in this display for C03.0. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 C03.0 an HCC code?
Yes. C03.0 (Malignant neoplasm of upper gum) maps to HCC 21, Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.671. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: C03.0 is billable and maps to V28 HCC 21, Lymphoma and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- C03.0
- Description
- Malignant neoplasm of upper gum
- HCC (V28)
- HCC 21 — Lymphoma and Other Cancers
- RAF reference coefficient
- 0.671
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work C03.0 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for C03.0
For C03.0, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- 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
Coder workflow notes
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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 Lymphoma and Other Cancers (HCC 21) with a source-labeled community, non-dual, aged reference coefficient of 0.671. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
Upper gum refers to the gingiva of the maxilla; distinguish from lower gum (C03.1). For C03.0, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, 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