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

Billable ICD-10-CM code, FY2026. Exempt from present-on-admission (POA) reporting.

Applies from Z28 Immunization not carried out and underimmunization status

Includes

• vaccination not carried out

Code also

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

MS-DRG index

Defines the logic of DRG(s) 795 in MDC 15.

Approximate ICD-9-CM (GEMs)

• V64.09 Vaccination not carried out for other reason (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Unacceptable principal diagnosis: These codes describe a circumstance which influences care but is not a current illness or injury, or capture only an underlying condition, and are unacceptable as principal diagnosis.

Code annotations containing back-references to Z28.20

Back-references to Z28.2

• Use Additional: Z28.3 Underimmunization status ("immunization not carried out because of patient decision for other and unspecified reason (Z28.2-)")

Back-references to Z28

• Code Also: Z71.85 Encounter for immunization safety counseling (", if applicable, immunization not carried out (Z28.-)")

Diagnosis Index entries for Z28.20

• Immunization › not done (not carried out) › because (of) › unspecified patient reason

Nearby codes

• Z28.03 Immunization not carried out because of immune compromised state of patient
• Z28.04 Immunization not carried out because of patient allergy to vaccine or component
• Z28.09 Immunization not carried out because of other contraindication
• Z28.1 Immunization not carried out because of patient decision for reasons of belief or group pressure
• Z28.2 Immunization not carried out because of patient decision for other and unspecified reason
• Z28.20 Immunization not carried out because of patient decision for unspecified reason (this code)
• Z28.21 Immunization not carried out because of patient refusal
• Z28.29 Immunization not carried out because of patient decision for other reason
• Z28.3 Underimmunization status
• Z28.31 Underimmunization for COVID-19 status
• Z28.310 Unvaccinated for COVID-19