2026 ICD-10-CM Diagnosis Code D84.81Immunodeficiency due to conditions classified elsewhere
ICD-10-CM Codes›D50–D89›D80-D89›D84
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
D84.81 is a billable ICD-10-CM diagnosis code for immunodeficiency due to conditions classified elsewhere. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 814 through 816. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 44 closely related codes. The code is a manifestation code that cannot be reported as the principal diagnosis. Coders also document this condition as immunodeficiency associated with chromosomal abnormality. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Immunity disorders.
D84.81 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 47 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 47, ESRD (V21) category 47, ESRD (V24) category 47, and RxHCC Part D (V08) category 99 for payment year 2026.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for D84.81.
Medicare Risk Adjustment (HCC)Billing
D84.81 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Immunodeficiency associated with chromosomal abnormality
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Code First
- underlying condition, such as:
- chromosomal abnormalities Q90 Q99
- diabetes mellitus E08 E13
- malignant neoplasms C00 C96
Type 1 Excludes
- certain disorders involving the immune mechanism D80 D83 D84.0 D84.1 D84.9
- human immunodeficiency virus [HIV] disease B20
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Immune System and Disorders
Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other diseases.
The full article covers:
- What is the immune system?
- What are the parts of the immune system?
- How does the immune system work?
- What are the types of immunity?
- What can go wrong with the immune system?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Code History & ChangesHistory
Replacement D84.81 replaces the following previously assigned code(s):
- D84.8 - Other specified immunodeficiencies
Questions About D84.81Overview
What is the ICD-10 code for immunodeficiency due to conditions classified elsewhere?
The ICD-10-CM code for immunodeficiency due to conditions classified elsewhere is D84.81 (sometimes written as D8481). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is D84.81 (Other specified immunodeficiencies) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report immunodeficiency due to conditions classified elsewhere on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does D84.81 group to?
On inpatient claims, immunodeficiency due to conditions classified elsewhere maps to MS-DRG 814, 815, 816, with relative weights from 0.6320 to 2.1267 depending on complications. Higher weights mean higher Medicare reimbursement.
Is D84.81 a CC or MCC?
CMS lists D84.81 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 44 closely related codes in its exclusion list.
Can D84.81 be a principal diagnosis?
No. This is a manifestation code: immunodeficiency due to conditions classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.
Does D84.81 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. D84.81 mapped to HCC 47 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 47 (Disorders of Immunity), ESRD (V21) category 47 (Disorders of Immunity), ESRD (V24) category 47 (Disorders of Immunity), and RxHCC Part D (V08) category 99 (Immune Disorders).
