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Z28 ICD-10-CM Code: Immunization not carried out and underimmunization status

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Coding at a Glance

Tabular directives
1 inclusion term · 1 code-also instruction

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for Z28 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • vaccination not carried out

Code Also

Additional codes that may be required to fully describe the encounter.

  • Code also, if applicable, encounter for immunization safety counseling (Z71.85)

Coder workflow for Z28

MedCoder structured workflow — derived from this code’s own official record

Before you code Z28

  1. Z28 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewZ28.0, Z28.1, Z28.2, Z28.3, Z28.8, Z28.9

    See the relationships section · Guide: How to choose an ICD-10-CM code →

  2. Confirm the reason for the encounter this Z code records: the circumstance it records. Check whether the code may be reported as first-listed or principal — some Z codes are limited to one position — and do not report a history or status code for a condition documented as current. Z code categories and their reporting positions (Guidelines I.C.21.c, I.C.21.c.15).

    Guide: Z codes as principal or first-listed diagnosis →

Choose the right path

  1. Does the documentation support one of the more specific codes beneath Z28?
    Yes → Select that code and continue the checks below on its own page.
    No → Z28 cannot be reported as written; query for the specificity its subcategory needs.

    ReviewZ28.0, Z28.1, Z28.2, Z28.3, Z28.8, Z28.9

Consider Z28. Then review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The reason for the encounter
Whether the code records the encounter’s purpose, a status, or a history — and whether it may be first-listed (Guidelines I.C.21.c).

Official instructions as workflow

  • Code Also — related condition(1 note)

    Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

    ReviewZ71.85

    See the official tabular notes · Guidelines I.A.17

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Immunization not carried out and underimmunization status is a non-billable ICD-10-CM category code (Z28). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Chapter 21: Factors influencing health status and contact with health services (Z00-Z99)

Miscellaneous Z codes/subcategories/categories: Z28 Immunization not carried out Except: Z28.3-, Underimmunization status Z29 Encounter for other prophylactic measures Z40 Encounter for prophylactic surgery Z41 Encounter for procedures for purposes other than remedying health state Except: Z41.9, Encounter for procedure for purposes other than remedying health state, unspecified Z53 Persons encountering health services for specific procedures and treatment, not carried out Z72 Problems related to lifestyle Note: These codes should be assigned only when the documentation specifies that the patient has an associated problem Z73 Problems related to life management difficulty Note: These codes should be assigned only when the documentation specifies that the patient has an associated problem. Z74 Problems related to care provider dependency Except: Z74.01, Bed confinement status Z75 Problems related to medical facilities and other health care Z76.0 Encounter for issue of repeat prescription

Verify Before Coding

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name Z28 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Code Also instruction: Z71.85 — Encounter for immunization safety counseling.

These codes suggest coding this condition alongside when both are present.

Contextual Map

Every relationship of Z28 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run Z28 with this related code in Claim Check

Hierarchy

Code Also

Referenced by Code Also instructions

Nearest codes (22)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Common coding questions

Can Z28 be billed directly?

No. Z28 (Immunization not carried out and underimmunization status) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "Z28 — Immunization not carried out and underimmunization status." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/z28-immunization-not-carried-out-and-underimmunization-status

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Immunization not carried out and underimmunization status

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Z28 in its code family, with their registry titles.