ICD-10 Z21
Billable / Specific HCC v28: 1Asymptomatic human immunodeficiency virus [HIV] infection status
About ICD-10-CM Z21
ICD-10-CM code Z21 represents Asymptomatic human immunodeficiency virus [HIV] infection status. This is a billable/specific code in the Factors Influencing Health Status chapter (block Z21). The 2026 edition of ICD-10-CM Z21 became effective on October 1, 2025.
Coding Tips for Z21
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
Z21 is a CMS-HCC v28 risk-adjustment code (category 1). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under Z21. Per CMS ICD-10-CM Tabular 2026.
- HIV positive NOS
Type 1 Excludes
Pure excludes, these codes can never be coded together with Z21. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- acquired immunodeficiency syndrome (B20)
- contact with human immunodeficiency virus [HIV] (Z20.6)
- exposure to human immunodeficiency virus [HIV] (Z20.6)
- human immunodeficiency virus [HIV] disease (B20)
- inconclusive laboratory evidence of human immunodeficiency virus [HIV] (R75)
Coding Notes
Code First
- Human immunodeficiency virus [HIV] disease complicating pregnancy, childbirth and the puerperium, if applicable (O98.7-)
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for Z21
Local Coverage Determinations (LCDs) from CMS MACs that list Z21 as a covered diagnosis.
Showing top 10 of 707 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing Z21.
1 Aetna
3 Cigna
5 Medicare
CPT Codes Commonly Billed with Z21
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert Z21 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| Z21 | V08 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To Z21
Other codes in section Z20-Z29 (Persons with potential health hazards related to communicable diseases).
ICD-10 Z21, Billing FAQ
Is ICD-10 code Z21 billable? +
Yes, Z21 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to Z21? +
ICD-10 Z21 includes: HIV positive NOS.
What codes are Type 1 Excludes for Z21? +
Type 1 Excludes (never code together with Z21): acquired immunodeficiency syndrome (B20); contact with human immunodeficiency virus [HIV] (Z20.6); exposure to human immunodeficiency virus [HIV] (Z20.6)
Does Z21 affect Medicare Advantage HCC risk adjustment? +
Yes. Z21 maps to CMS-HCC v28 category 1. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What ICD-9 codes does Z21 map to? +
Per CMS GEMs, Z21 maps to ICD-9 codes: V08. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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