MCMedicalCodingSoftware
B27.9

B27.9: Infectious mononucleosis, unspecified

Non-billable headerICD-10-CM

B27.9 is a non-billable header ICD-10-CM code for infectious mononucleosis, unspecified. It cannot be billed on its own: choose one of the more specific child codes below.

Other codes that can never be billed with B27.9

Their own Excludes1 notes name this code, so the conflict is not listed above.

  • G02Meningitis in other infectious and parasitic diseases classified elsewhere
  • G63Polyneuropathy in diseases classified elsewhere
  • J02.8Acute pharyngitis due to other specified organisms
  • D72.821Monocytosis (symptomatic)

Risk adjustment

No CMS-HCC V28 category: this code does not change a RAF score.

Code history

Unchanged in every release from FY2024 to FY2027.

Code to one of these instead B27.9

4 child codes. Green means billable.

Other codes under B27

ICD-10-CMFY2027· effective October 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release: see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.