C06.80
BillableMalignant neoplasm of overlapping sites of unspecified parts of mouth
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C06.80 an HCC code?
Yes. C06.80 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 C06.80
For C06.80to 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 C06.80 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C06.80 is the ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of unspecified parts of mouth. Cancer involving multiple overlapping areas of the mouth when the specific parts cannot be identified. C06.80 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, C06.80 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, C06.80 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.
Use this code only when documentation indicates overlapping sites but the exact locations are unspecified. Because C06.80 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 C06.80 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when documentation indicates overlapping sites but the exact locations are unspecified
- •Review pathology reports to determine if more specific site codes are appropriate
Clinical Significance
This code represents oral cancer spanning multiple overlapping mouth sites where the specific parts involved are unspecified. This combination of overlapping nature and lack of specificity suggests documentation gaps that should be addressed through provider queries and imaging review.
Documentation Requirements
- ✓Pathology confirming malignancy involving multiple oral sites
- ✓Documentation indicating overlapping involvement across mouth regions
- ✓Provider query documentation explaining why specific sites cannot be identified
- ✓Imaging reports describing extent of tumor involvement
- ✓TNM staging reflecting the advanced, multi-site nature of the disease
Commonly Confused Codes
- •C06.89 — Overlapping sites of other parts of mouth; use when at least one specific site can be identified
- •C06.9 — Mouth, unspecified; use when there is no overlapping involvement, just unknown location
- •C14.8 — Overlapping sites of lip, oral cavity and pharynx; use when tumor extends beyond mouth into pharynx
- •C04.8 — Overlapping sites of floor of mouth; use when overlapping is confined to floor of mouth