D81.2 ICD-10-CM Code: Severe combined immunodeficiency [SCID] with low or normal B-cell numbers
D81.2 maps to CMS-HCC V28 114 (RAF 2.262). Documentation must support MEAT. MEAT criteria · RAF calculator · free HCC coding tools
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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)
D81.2
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceSevere combined immunodeficiency [SCID] with low or normal B-cell numbers
A severe inherited immune deficiency where T-cells are absent or very low while B-cells are either low or normal in number.
Buddy Insight
Severe combined immunodeficiency with low or normal B-cell numbers represents a SCID phenotype where T-cell development is profoundly impaired while B-cell numbers may be preserved, though B-cell function is still compromised due to lack of T-cell help.
CMS-HCC V28
MappedHCC 114
RAF 2.262
CMS-HCC V24
MappedHCC 47
RAF 0.665
ACA/HHS
MappedHCC 73
Varies by metal level
ESRD/PACE
MappedHCC 47
RAF 0.078
RXHCC
MappedHCC 99
RAF 0.943
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for D81.2 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for D81.2 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for D81.2 in this effective period.
Excludes 1
Official- autosomal recessive agammaglobulinemia (Swiss type) (D80.0)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for D81.2 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for D81.2 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for D81.2 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is D81.2 an HCC code?
Yes. D81.2 (Severe combined immunodeficiency [SCID] with low or normal B-cell numbers) maps to Common Variable and Combined Immunodeficiencies under the CMS-HCC V28 risk adjustment model (and Disorders of Immunity under V24), with a community non-dual aged RAF of 2.262. It is billable for payment year 2026.
Coder answer: D81.2 is billable and maps to V28 HCC 114, Common Variable and Combined Immunodeficiencies. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- D81.2
- Description
- Severe combined immunodeficiency [SCID] with low or normal B-cell numbers
- HCC (V28)
- HCC 114 — Common Variable and Combined Immunodeficiencies
- RAF
- 2.262
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.
Work D81.2 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for D81.2
For D81.2 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 D81.2 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
D81.2 is the ICD-10-CM diagnosis code for severe combined immunodeficiency [scid] with low or normal b-cell numbers. A severe inherited immune deficiency where T-cells are absent or very low while B-cells are either low or normal in number. D81.2 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, D81.2 maps to Common Variable and Combined Immunodeficiencies (HCC 114) with a community, non-dual, aged base RAF weight of 2.262. Under the older CMS-HCC V24 model, D81.2 maps to Disorders of Immunity (HCC 47) with a community, non-dual, aged base RAF weight of 0.665. 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.
Differentiate from D81.1 by verifying B-cell count status (low vs. normal). Because D81.2 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 D81.2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Differentiate from D81.1 by verifying B-cell count status (low vs. normal)
- •Document specific T-cell and B-cell counts from immunological testing
Clinical Significance
Severe combined immunodeficiency with low or normal B-cell numbers represents a SCID phenotype where T-cell development is profoundly impaired while B-cell numbers may be preserved, though B-cell function is still compromised due to lack of T-cell help. This T-negative, B-positive phenotype is commonly associated with interleukin-7 receptor alpha chain deficiency or Janus kinase 3 deficiency.
Documentation Requirements
- ✓Documentation must include flow cytometry showing absent or profoundly reduced T-cells with preserved or low B-cell counts, natural killer cell enumeration, immunoglobulin levels, genetic testing when performed, and treatment including hematopoietic stem cell transplantation or gene therapy.
- ✓Document the specific immunological phenotype (T-B+ or T-B-) to support code assignment.
Commonly Confused Codes
- •D81.1 (severe combined immunodeficiency with low T
- •and B-cell numbers, where B-cells are also severely reduced), D81.4 (Nezelof syndrome with low T-cells and normal B-cells but less severe than SCID), D81.31 (severe combined immunodeficiency due to adenosine deaminase deficiency with a specific enzymatic cause), D81.0 (severe combined immunodeficiency with reticular dysgenesis including myeloid failure).