Z21 — Asymptomatic human immunodeficiency virus [HIV] infection status
Is Z21 billable?
Yes — Z21 is billable for FY2027. Z21 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. Z21 may be submitted for encounters from October 1, 2026 through September 30, 2027.
Z21 at a glance
| Code | Z21 |
|---|---|
| Description | Asymptomatic human immunodeficiency virus [HIV] infection status |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
What Medicare edits apply to Z21?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name Z21 directly.
CMS does not consider this code, on its own, sufficient justification for admission to an acute care hospital when reported as the principal diagnosis.
Which MS-DRGs does Z21 group to?
Z21 sits in MDC 18 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 865Viral Illness with MCCmedical
- 866Viral Illness without MCCmedical
How is Z21 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to Z21. They show the wording a clinician may have documented, which often differs from the Tabular description.
- HIV › positive, seropositive
- Status › human immunodeficiency virusinfection, asymptomatic (post)
- Syndrome › retroviral seroconversion
- Syndrome › seroconversion, retroviral
- Human › immunodeficiency virus › asymptomatic status
- Test, tests, testing › HIV › positive (for)
- Test, tests, testing › HIV › seropositive (for)
Excludes1 — never code together
The conditions below can never be reported together with Z21 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Code first
The underlying condition below must be sequenced before Z21. Z21 describes a manifestation and cannot be the principal or first-listed diagnosis.
- Human immunodeficiency virus [HIV] disease complicating pregnancy, childbirth and the puerperium, if applicable (O98.7-)
Inclusion terms
Alternative wording in documentation that is classified to Z21.
- HIV positive NOS
How long has Z21 existed?
Z21 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with Z21?
ICD-10-CM declares these codes mutually exclusive with Z21 — exactly one of each pair can be correct for a given encounter.