2026 ICD-10-CM Diagnosis Code C06.89Malignant neoplasm of overlapping sites of other parts of mouth
ICD-10-CM Codes›C00–D49›C00-C14›C06
- Billable — Valid for Submission
- Risk Adjusts — HCC 21
- Chronic Condition
C06.89 is a billable ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of other parts of mouth. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 11 through 13, 146 through 148. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Head and neck cancers - lip and oral cavity.
For Medicare Advantage risk adjustment, C06.89 maps to CMS-HCC Category 21 (Lymphoma and Other Cancers) under the V28 model, adding a risk factor of about 0.671 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C06.89 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- 'book leaf' neoplasm [ventral surface of tongue and floor of mouth]
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of NeoplasmsClinical
Patient EducationClinical
Oral Cancer
Oral cancer is cancer of the mouth. It is a type of head and neck cancer. Most oral cancers are squamous cell cancers. They begin in the flat cells that cover the surfaces of your mouth, tongue, and lips. The cancer cells may spread into deeper tissue as the cancer grows.
The full article covers:
- What is oral cancer?
- Who is more likely to develop oral cancer?
- What are the symptoms of oral cancer?
- How is oral cancer diagnosed?
- What are the treatments for oral cancer?
- Can oral cancer be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C06.89 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C06.89Overview
What is the ICD-10 code for malignant neoplasm of overlapping sites of other parts of mouth?
The ICD-10-CM code for malignant neoplasm of overlapping sites of other parts of mouth is C06.89 (sometimes written as C0689). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is C06.89 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of overlapping sites of other parts of mouth on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C06.89 group to?
When malignant neoplasm of overlapping sites of other parts of mouth is the principal diagnosis on an inpatient stay, it groups to MS-DRG 11, 12, 13, 146, 147, 148, with relative weights from 0.7971 to 5.4541 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of C06.89?
Under the General Equivalence Mappings, malignant neoplasm of overlapping sites of other parts of mouth converts to ICD-9-CM 145.8 (malig neoplasm mouth NEC). The mapping is approximate, so confirm the match fits the documentation.
What HCC is C06.89?
C06.89 (malignant neoplasm of overlapping sites of other parts of mouth) maps to CMS-HCC Category 21 (Lymphoma and Other Cancers), commonly written as HCC 21, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 11 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 22.
Does C06.89 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C06.89 adds a risk adjustment factor of about 0.671 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.493 to 0.739 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, and HCC 20) supersedes it when both are reported. See the full factor table on the HCC 21 category page.
