2026 ICD-10-CM Diagnosis Code Z28Immunization not carried out and underimmunization status

ICD-10-CM Codes›Z00–Z99›Z20-Z29›Z28

ICD-10-CM Z28
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z28 is a non-billable ICD-10-CM category code for immunization not carried out and underimmunization status, so it cannot be submitted on claims. Use a more specific code from this category instead, such as Z28.01, Z28.02, Z28.03, and Z28.04.

Code Identity

ICD-10-CM Code
Z28
Billable Status
No — Non-Billable Category
Code Describes
Immunization not carried out and underimmunization status
Chapter
Z20-Z29
Persons with potential health hazards related to communicable diseases

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ20-Z29Persons with potential health hazards related to communicable diseases
CategoryZ28Immunization not carried out and underimmunization status
This CodeZ28Immunization not carried out and underimmunization status

Specific Coding for Immunization not carried out and underimmunization statusOverview

Non-specific codes like Z28 require more characters. Use one of these billable codes instead:

  • Z28.0 for Immunization not carried out because of contraindication

  • Use Z28.01 for Immunization not carried out because of acute illness of patient

  • Use Z28.02 for Immunization not carried out because of chronic illness or condition of patient

  • Use Z28.03 for Immunization not carried out because of immune compromised state of patient

  • Use Z28.04 for Immunization not carried out because of patient allergy to vaccine or component

  • Use Z28.09 for Immunization not carried out because of other contraindication

  • Use Z28.1 for Immunization not carried out because of patient decision for reasons of belief or group pressure

  • Z28.2 for Immunization not carried out because of patient decision for other and unspecified reason

  • Use Z28.20 for Immunization not carried out because of patient decision for unspecified reason

  • Use Z28.21 for Immunization not carried out because of patient refusal

  • Use Z28.29 for Immunization not carried out because of patient decision for other reason

  • Z28.3 for Underimmunization status

  • Z28.31 for Underimmunization for COVID-19 status

  • Use Z28.39 for Other underimmunization status

  • Z28.8 for Immunization not carried out for other reason

  • Use Z28.81 for Immunization not carried out due to patient having had the disease

  • Use Z28.82 for Immunization not carried out because of caregiver refusal

  • Use Z28.83 for Immunization not carried out due to unavailability of vaccine

  • Use Z28.89 for Immunization not carried out for other reason

  • Use Z28.9 for Immunization not carried out for unspecified reason

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Includes

  • vaccination not carried out

Code Also

  • , if applicable, encounter for immunization safety counseling Z71.85

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Z28Overview

Is Z28 (Immunization not carried out and underimmunization status) a billable code?

No. This is a category header that groups the codes for immunization not carried out and underimmunization status, and headers cannot be submitted on claims. Claims for immunization not carried out and underimmunization status need a more specific code from this category, such as Z28.01, Z28.02, and Z28.03.