ICD-10 C04.9
Billable / Specific HCC v28: 11Malignant neoplasm of floor of mouth, unspecified
About ICD-10-CM C04.9
ICD-10-CM code C04.9 represents Malignant neoplasm of floor of mouth, unspecified. This is a billable/specific code in the Neoplasms chapter (block C04). The 2026 edition of ICD-10-CM C04.9 became effective on October 1, 2025.
Coding Tips for C04.9
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
C04.9 is a CMS-HCC v28 risk-adjustment code (category 11). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for C04.9
Local Coverage Determinations (LCDs) from CMS MACs that list C04.9 as a covered diagnosis.
Showing top 10 of 442 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing C04.9.
1 Cigna
5 Medicare
CPT Codes Commonly Billed with C04.9
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 63621 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- 61800 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- 77373 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- G0339 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- 77372 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- G0563 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- 77435 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- 77371 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- G0340 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
- 61798 CMS LCD: Billing and Coding: Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) CMS LCD
Convert C04.9 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| C04.9 | 1449 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To C04.9
Other codes in section C00-C14 (Malignant neoplasms of lip, oral cavity and pharynx).
ICD-10 C04.9, Billing FAQ
Is ICD-10 code C04.9 billable? +
Yes, C04.9 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does C04.9 affect Medicare Advantage HCC risk adjustment? +
Yes. C04.9 maps to CMS-HCC v28 category 11. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What CPT codes are commonly billed with C04.9? +
Procedures frequently paired with C04.9 include: 63621, 61800, 77373, G0339, 77372.
What ICD-9 codes does C04.9 map to? +
Per CMS GEMs, C04.9 maps to ICD-9 codes: 1449. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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