D84.1 vs D84.81
D84.1 (Defects in the complement system) compared with D84.81 (Immunodeficiency due to conditions classified elsewhere), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. D84.81 carries an Excludes1 note covering D84.1: “certain disorders involving the immune mechanism (D80-D83, D84.0, D84.1, D84.9)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| D84.1Defects in the complement system | D84.81Immunodeficiency due to conditions classified elsewhere | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | D50-D89 — Diseases of the Blood and Blood-forming Organs and Certain Disorders Involving the Immune Mechanism (D50-D89) | D50-D89 — Diseases of the Blood and Blood-forming Organs and Certain Disorders Involving the Immune Mechanism (D50-D89) |
| Definition | Defects in the complement system is a billable ICD-10-CM diagnosis code (D84.1). | Immunodeficiency due to conditions classified elsewhere is a billable ICD-10-CM diagnosis code (D84.81). |
| Includes | defects in the complement system immunodeficiency disorders, except human immunodeficiency virus [HIV] disease sarcoidosis C1 esterase inhibitor [C1-INH] deficiency | defects in the complement system immunodeficiency disorders, except human immunodeficiency virus [HIV] disease sarcoidosis |
| Code first | — | underlying condition, such as: chromosomal abnormalities (Q90-Q99) |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources