C05.1
BillableMalignant neoplasm of soft palate
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C05.1 an HCC code?
Yes. C05.1 maps to Lymphoma and Other Cancers 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 C05.1
For C05.1to 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 C05.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C05.1 is the ICD-10-CM diagnosis code for malignant neoplasm of soft palate. Cancer that develops in the soft palate, the muscular tissue forming the back portion of the roof of the mouth. C05.1 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, C05.1 maps to Lymphoma and Other Cancers (HCC 21) with a community, non-dual, aged base RAF weight of 0.671. Under the older CMS-HCC V24 model, C05.1 maps to Colorectal, Bladder, and Other Cancers (HCC 11) with a community, non-dual, aged base RAF weight of 0.307. 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.
Soft palate cancers may extend to adjacent structures like tonsils or pharynx. Because C05.1 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 C05.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Soft palate cancers may extend to adjacent structures like tonsils or pharynx
- •Document any extension beyond soft palate for staging purposes
Clinical Significance
Malignant neoplasm of the soft palate affects the muscular posterior portion of the roof of the mouth. This cancer is clinically important because the soft palate's role in speech and swallowing means that treatment significantly impacts quality of life, and tumors here frequently extend to adjacent oropharyngeal structures.
Documentation Requirements
- ✓Pathology-confirmed malignancy specifying soft palate origin
- ✓Documentation distinguishing soft palate from hard palate location
- ✓Assessment of extension to adjacent structures (tonsils, pharyngeal wall, uvula)
- ✓TNM staging with particular attention to depth and nodal status
- ✓Functional assessment of speech and swallowing
Excludes 2 — Not included here, may code separately
- malignant neoplasm of nasopharyngeal surface of soft palate (C11.3)
Commonly Confused Codes
- •C05.0 — Malignant neoplasm of hard palate; the hard palate is the anterior bony portion
- •C05.2 — Malignant neoplasm of uvula; the uvula hangs from the posterior edge of the soft palate
- •C10.9 — Malignant neoplasm of oropharynx, unspecified; soft palate cancers may extend into oropharynx
- •C09.9 — Malignant neoplasm of tonsil; adjacent structure frequently involved with soft palate tumors