FY2027
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Excludes1 pair

B20 vs Z20.6

B20 and Z20.6 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.

The official note, declared on B20
exposure to HIV virus (Z20.6)
B20

Human immunodeficiency virus [HIV] disease

Billable
Chapter 1
Certain infectious and parasitic diseases
Section
B20
Use when the record says
  • acquired immune deficiency syndrome [AIDS]
  • AIDS-related complex [ARC]
  • HIV infection, symptomatic
Indexed under
  • AIDS (related complex)
  • ARC (AIDS-related complex)
  • HIV
  • Slim disease (in HIV infection)
  • Acquired › immunodeficiency syndrome (AIDS)
Z20.6

Contact with and (suspected) exposure to human immunodeficiency virus [HIV]

Billable
Chapter 21
Factors influencing health status and contact with health services
Section
Z20-Z29
Indexed under
  • Contact › AIDS virus
  • Contact › HIV
  • Contact › HTLV-III/LAV
  • Contact › human immunodeficiency virus (HIV)
  • Exposure › AIDS virus

These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.

Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027