What is ICD-10 code D80.9?

D80.9 is the ICD-10-CM diagnosis code for Immunodeficiency with predominantly antibody defects, unspecified. It belongs to the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89). D80.9 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. D80.9 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. D80.9 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. D80.9 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for D80.9?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. D80.9 was a payment HCC under V24 (Disorders of Immunity) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting D80.9?

Use this code only when the documentation indicates an antibody deficiency but does not specify the type (such as IgA, IgG, or IgM deficiency); if a specific antibody deficiency is documented, use the more specific code instead This is an unspecified code (ending in .9), so query the provider if more specific information about the type of antibody defect is available in the medical record to ensure accurate coding Because D80.9 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

D80.9: Immunodeficiency with predominantly

ICD-10-CM Code View

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Code lookupD80.9Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89) / Certain disorders involving the immune mechanism (D80-D89)

D80.9

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Immunodeficiency with predominantly antibody defects, unspecified

This code describes a condition where the immune system doesn't produce enough antibodies to fight infections, but the specific type of antibody deficiency is not specified. Patients with this condition are more susceptible to bacterial infections and may require immunoglobulin replacement therapy.

Buddy Insight

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Mapped

HCC 47

Disorders of Immunity

RAF 0.472

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 47

Disorders of Immunity

RAF 0.0

RXHCC

Mapped

HCC 99

Immunodeficiencies

RAF 0.0

Code Trumping

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Code Book Path

Official

D80Immunodeficiency with predominantly antibody defects

D80.9Immunodeficiency with predominantly antibody defects, unspecified

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for D80.9 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for D80.9 in this effective period.

Related Child Codes

Official

D80.0Hereditary hypogammaglobulinemia

D80.1Nonfamilial hypogammaglobulinemia

D80.2Selective deficiency of immunoglobulin A [IgA]

D80.3Selective deficiency of immunoglobulin G [IgG] subclasses

D80.4Selective deficiency of immunoglobulin M [IgM]

Includes

Official

ICD-10-CM does not list Includes notes for D80.9 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for D80.9 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for D80.9 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for D80.9 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for D80.9 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation should include evidence supporting an antibody deficiency diagnosis (recurrent infections, low immunoglobulin levels), the reason why further specificity is unavailable, and the plan for additional workup to characterize the defect.

Include any immunoglobulin levels tested and vaccine challenge responses if performed.

Query the provider for more specific information when possible.

MEAT Support

HCC Buddy guidance

Include any immunoglobulin levels tested and vaccine challenge responses if performed.

Query the provider for more specific information when possible.

Audit Caution

HCC Buddy guidance

This unspecified code should only be used when documentation genuinely lacks specificity about the type of antibody deficiency.

It is a high audit-risk code because reviewers will look for available immunological test results that might support a more specific code.

Never use this code when the medical record contains enough information to assign D80.0 through D80.8.

Common Mistakes

HCC Buddy guidance

D80.2 (selective Immunoglobulin A deficiency), D80.3 (selective Immunoglobulin G subclass deficiency), D80.4 (selective Immunoglobulin M deficiency), D83.9 (common variable immunodeficiency, unspecified, which requires CVID diagnostic criteria to be met), D84.9 (immunodeficiency, unspecified, an even broader code).

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is D80.9 an HCC code?

Yes. D80.9 maps to Disorders of Immunity under the V24 model but is not retained in V28.

HCC Category Mapping

V24HCC 47, Disorders of Immunity

0.472

ESRDHCC 47, Disorders of Immunity

0.000

RxHCCHCC 99, Immunodeficiencies

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for D80.9

For D80.9to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed D80.9 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

D80.9 is the ICD-10-CM diagnosis code for immunodeficiency with predominantly antibody defects, unspecified. This code describes a condition where the immune system doesn't produce enough antibodies to fight infections, but the specific type of antibody deficiency is not specified. Patients with this condition are more susceptible to bacterial infections and may require immunoglobulin replacement therapy. D80.9 sits in the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89), within the section covering certain disorders involving the immune mechanism (d80-d89).

Under the older CMS-HCC V24 model, D80.9 maps to Disorders of Immunity (HCC 47) with a community, non-dual, aged base RAF weight of 0.472. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Use this code only when the documentation indicates an antibody deficiency but does not specify the type (such as IgA, IgG, or IgM deficiency); if a specific antibody deficiency is documented, use the more specific code instead. Because D80.9 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for D80.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code only when the documentation indicates an antibody deficiency but does not specify the type (such as IgA, IgG, or IgM deficiency); if a specific antibody deficiency is documented, use the more specific code instead
•This is an unspecified code (ending in .9), so query the provider if more specific information about the type of antibody defect is available in the medical record to ensure accurate coding

Clinical Significance

Immunodeficiency with predominantly antibody defects, unspecified, indicates that a patient has been diagnosed with an antibody-mediated immunodeficiency but the specific type has not been determined or documented. These patients typically present with recurrent bacterial infections and may require immunoglobulin replacement therapy pending further immunological characterization.

Documentation Requirements

✓Documentation should include evidence supporting an antibody deficiency diagnosis (recurrent infections, low immunoglobulin levels), the reason why further specificity is unavailable, and the plan for additional workup to characterize the defect.
✓Include any immunoglobulin levels tested and vaccine challenge responses if performed.
✓Query the provider for more specific information when possible.

Commonly Confused Codes

•D80.2 (selective Immunoglobulin A deficiency), D80.3 (selective Immunoglobulin G subclass deficiency), D80.4 (selective Immunoglobulin M deficiency), D83.9 (common variable immunodeficiency, unspecified, which requires CVID diagnostic criteria to be met), D84.9 (immunodeficiency, unspecified, an even broader code).