Z28.3

ICD-10Non-billable category

Underimmunization status

Official ICD-10-CM descriptor (FY2026)

Underimmunization status

Z28.3 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.

Use additional code

Report an additional code to identify the associated condition.

  • code, if applicable, to identify:
  • immunization not carried out because of contraindication (Z28.0-)
  • immunization not carried out because of patient decision for other and unspecified reason (Z28.2-)
  • immunization not carried out because of patient decision for reasons of belief or group pressure (Z28.1)
  • immunization not carried out for other reason (Z28.8-)

ICD-10-CM FY2026 defines 2 codes beneath Z28.3. See the ICD-10-CM index for what this site publishes.

Related codes in Z28

Where this code sits

Parent code
Z28

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Source

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.

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