B27.99
✓ Billable
Infectious mononucleosis, unspecified with other complication
ICD-10-CM · FY2026 · Certain Infectious and Parasitic Diseases
Code
B27.99
System
ICD-10-CM
Billable
Yes — valid for submission
Effective
FY2026
Chapter
Certain Infectious and Parasitic Diseases
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 B27.99?
ICD-10-CM code B27.99 represents Infectious mononucleosis, unspecified with other complication. It is a billable diagnosis code in the Certain Infectious and Parasitic Diseases chapter, effective October 1, 2025 – September 30, 2026.
Is B27.99 billable?
Yes. B27.99 is a valid billable ICD-10-CM code for insurance claims and clinical documentation.
What chapter is B27.99 in?
B27.99 belongs to the Certain Infectious and Parasitic Diseases chapter (A00–B99) of ICD-10-CM.
Related codes in the B27 category
B27
Infectious mononucleosis
Non-billable
B27.0
Gammaherpesviral mononucleosis
Non-billable
B27.1
Cytomegaloviral mononucleosis
Non-billable
B27.8
Other infectious mononucleosis
Non-billable
B27.9
Infectious mononucleosis, unspecified
Non-billable
B27.00
Gammaherpesviral mononucleosis without complication
Billable
B27.01
Gammaherpesviral mononucleosis with polyneuropathy
Billable
B27.02
Gammaherpesviral mononucleosis with meningitis
Billable
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