D83.1
BillableCommon variable immunodeficiency with predominant immunoregulatory T-cell disorders
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D83.1 an HCC code?
Yes. D83.1 maps to Severe Combined Immunodeficiency and Other Immune Disorders under the CMS-HCC V28 risk adjustment model (and Disorders of Immunity under V24).
HCC Category Mapping
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 D83.1
For D83.1 to 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 D83.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D83.1 is the ICD-10-CM diagnosis code for common variable immunodeficiency with predominant immunoregulatory t-cell disorders. A common immune disorder where T-cells (immune cells that regulate immune response) are abnormal or insufficient in number or function. D83.1 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 CMS-HCC V28 risk adjustment model, D83.1 maps to Severe Combined Immunodeficiency and Other Immune Disorders (HCC 114) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, D83.1 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.
Document T-cell count and function test results to support this diagnosis. Because D83.1 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 D83.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document T-cell count and function test results to support this diagnosis
- •Differentiate from D83.0 by confirming T-cell dysfunction is the predominant abnormality
Clinical Significance
Common variable immunodeficiency with predominant immunoregulatory T-cell disorders represents a subset of common variable immunodeficiency where T-cell dysfunction is the primary driver of immune dysregulation, despite the hallmark antibody deficiency. These patients often have more pronounced granulomatous disease, splenomegaly, and autoimmune complications compared to those with primarily B-cell abnormalities.
Documentation Requirements
- ✓Documentation must include evidence of T-cell dysfunction (reduced CD4 counts, abnormal T-cell proliferation assays, reversed CD4/CD8 ratio), immunoglobulin levels confirming hypogammaglobulinemia, and clinical rationale for identifying T-cell disorder as the predominant abnormality.
- ✓Document granulomatous disease, splenomegaly, autoimmune manifestations, and response to immunoglobulin replacement therapy.