Z28
ICD-10Non-billable categoryImmunization not carried out and underimmunization status
Official ICD-10-CM descriptor (FY2026)
Immunization not carried out and underimmunization status
Z28 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.
Includes
- vaccination not carried out
Code also
Two codes may be needed; sequencing depends on the reason for the encounter.
- , if applicable, encounter for immunization safety counseling (Z71.85)
More specific codes under Z28
- Z28.0Immunization not carried out because of contraindicationcategory
- Z28.1Immuniz not crd out because of patient belief/grp pressr
- Z28.2Immuniz not crd out bec pt decision for oth and unsp reasoncategory
- Z28.3Underimmunization statuscategory
- Z28.8Immunization not carried out for other reasoncategory
- Z28.9Immunization not carried out for unspecified reason
Where this code sits
Krasyn AI Coder
Get code suggestions automatically as you type notes. Free for 50 analyses.
Install for Chrome — freeSource
ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.