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Z28.3

Non-billable

Underimmunization status

Z28.3 is the ICD-10-CM code for Underimmunization status. It is a non-billable category code — use a more specific child code such as Z28.31 for billing.

Status
Header (non-billable)
Chapter
Z00-Z99
Parent
Z28
Subcodes
2
Edition
FY2026

Z00-Z99 Factors influencing health status and contact with health services

Use additional code

  • •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-)

Frequently asked questions

What is ICD-10 code Z28.3?
Z28.3 is the ICD-10-CM code for "Underimmunization status". It falls under Z00-Z99 Factors influencing health status and contact with health services.
Is Z28.3 a billable code?
No — Z28.3 is a non-billable header code. Use a more specific child code (such as Z28.31) for billing.
What are the subcodes of Z28.3?
Z28.3 has 2 more specific child codes, including Z28.31, Z28.39.

Source: CMS ICD-10-CM FY2026. For informational purposes only — not medical advice. See our medical disclaimer.

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