Z28 – Immunization not carried out and underimmunization status

ICD-10-CM 2027 diagnosis code · Persons with potential health hazards related to communicable diseases

Non-billable header

ICD-10-CM code Z28

Code: Z28 (claims format: Z28)
Description: Immunization not carried out and underimmunization status
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 21. Factors influencing health status and contact with health services (Z00-Z99)
Block: Z20-Z29 Persons with potential health hazards related to communicable diseases

Billable codes under Z28

Z28 is a header code and cannot be used on claims. Choose the most specific code:

Z28.0 – Immunization not carried out because of contraindicationHeader (more codes below)
Z28.1 – Immunization not carried out because of patient decision for reasons of belief or group pressureBillable
Z28.2 – Immunization not carried out because of patient decision for other and unspecified reasonHeader (more codes below)
Z28.3 – Underimmunization statusHeader (more codes below)
Z28.8 – Immunization not carried out for other reasonHeader (more codes below)
Z28.9 – Immunization not carried out for unspecified reasonBillable

Notes for Z28

Includes:

vaccination not carried out

Code also:

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

Frequently asked questions

What is ICD-10 code Z28?

Z28 is the ICD-10-CM code for immunization not carried out and underimmunization status, in the block Z20-Z29 (Persons with potential health hazards related to communicable diseases).

Is Z28 a billable code?

No. Z28 is a header code with more specific child codes; report one of the billable codes listed above.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.