ICD-10-CM 2027 diagnosis code

C04Malignant neoplasm of floor of mouth

Not billable — use a more specific code

C04 is a header code, so it can't be reported by itself. Choose one of the 4 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About C04

C04 is the ICD-10-CM diagnosis code for malignant neoplasm of floor of mouth. It belongs to block C00-C14 (malignant neoplasms of lip, oral cavity and pharynx) and chapter 2 (neoplasms). It is a header code, so it can't be reported by itself; one of its 4 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: C04.0 (mouth), C04.1 (mouth), C04.8 (mouth) and C04.9 (unspecified).

Use an additional code to identify: alcohol abuse and dependence (F10.-), history of tobacco dependence (Z87.891), tobacco dependence (F17.-) and tobacco use (Z72.0).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under C04

Coding notes

Use additional codeAdd a secondary code to fully describe the condition

code to identify:
alcohol abuse and dependence (F10.-)
history of tobacco dependence (Z87.891)
tobacco dependence (F17.-)
tobacco use (Z72.0)

Notes that apply from higher levels

Instructions written at a parent level also apply to C04.

Broader instructions also apply from Chapter 2: Neoplasms.

Code history

2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about C04

Is C04 billable?: No. C04 is a header code. Report one of its more specific subcodes instead.