C31
⚠ Non-billable
Malignant neoplasm of accessory sinuses
ICD-10-CM · FY2026 · Neoplasms
Code
C31
System
ICD-10-CM
Billable
No — use specific code
Effective
FY2026
Chapter
Neoplasms
Source
CMS / CDC NCHS
⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.
Frequently asked questions
What is ICD-10 code C31?
ICD-10-CM code C31 represents Malignant neoplasm of accessory sinuses. It is a non-billable header code requiring a more specific subcategory in the Neoplasms chapter, effective October 1, 2025 – September 30, 2026.
Is C31 billable?
No. C31 is a non-billable header. Select a more specific subcategory for claims submission.
What chapter is C31 in?
C31 belongs to the Neoplasms chapter (C00–D49) of ICD-10-CM.
Related codes in the C31 category
C31.0
Malignant neoplasm of maxillary sinus
Billable
C31.1
Malignant neoplasm of ethmoidal sinus
Billable
C31.2
Malignant neoplasm of frontal sinus
Billable
C31.3
Malignant neoplasm of sphenoid sinus
Billable
C31.8
Malignant neoplasm of overlapping sites of accessory sinuses
Billable
C31.9
Malignant neoplasm of accessory sinus, unspecified
Billable
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