2027 ICD-10-CM Diagnosis Code Z28.20Immunization not carried out because of patient decision for unspecified reason

ICD-10-CM Codes›Z00–Z99›Z20-Z29›Z28

ICD-10-CM Z28.20
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Z28.20 is a billable ICD-10-CM diagnosis code for immunization not carried out because of patient decision for unspecified reason. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 795, 951. The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under No immunization or underimmunization.

Code Identity

ICD-10-CM Code
Z28.20
Billable Status
Yes — Valid for Submission
Code Describes
Immunization not carried out because of patient decision for unspecified reason
Short Description
Immuniz not crd out bec patient decision for unsp reason
Parent Code
Z28.2
Immunization not carried out because of patient decision for other and unspecified reason

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ20-Z29Persons with potential health hazards related to communicable diseases
CategoryZ28Immunization not carried out and underimmunization status
This CodeZ28.20Immunization not carried out because of patient decision for unspecified reason

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z28.20.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Present on Admission (POA)Billing

Z28.20 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Persons with potential health hazards related to communicable diseases (Z20-Z29).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Booster meningitis C vaccination declined
  • Herpes zoster vaccination declined
  • Immunization consent not given
  • Meningitis C immunization declined
  • Meningococcal vaccination declined
  • No consent - BCG
  • No consent - diphtheria immunization
  • No consent - influenza immunization
  • No consent - measles immunization
  • No consent - pertussis immunization
  • No consent - polio immunization
  • No consent - pre-school vaccinations
  • No consent - rubella immunization
  • No consent - school exit vaccinations
  • No consent - tetanus immunization
  • No consent - Tetanus/low dose diphtheria vaccine
  • No consent DT immunization
  • No consent DTP immunization
  • No consent for any immunization
  • No consent for any primary immunization
  • No consent for Haemophilus influenzae type b immunization
  • No consent for meningitis C immunization
  • No consent for MMR
  • No consent for MMR1
  • No consent for MMR2
  • No consent for MR - Measles/rubella vaccine
  • No consent for third Haemophilus influenzae type b vaccine booster
  • No consent pneumococcal immunization
  • Temporal finding
  • Tetanus diphtheria and acellular pertussis vaccination declined

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Z28.20: its own notes plus those printed at Z28 and Chapter 21. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Z28 Immunization not carried out and underimmunization status applies to 17 codes
  • vaccination not carried out

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From Z28 Immunization not carried out and underimmunization status applies to 17 codes
  • if applicable, encounter for immunization safety counseling (Z71.85)

Notes

General instructions on how these codes are used.

From Chapter 21 (Z00-Z99) Factors influencing health status and contact with health services applies to 1,425 codes
  • Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
  • (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
  • (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Z28.20, its category, or a range that includes it.

Use Additional Code 1

These codes say to use an additional code from the note, and Z28.20 is one of the codes named.

  • Z28.3 Underimmunization status
    immunization not carried out because of patient decision for other and unspecified reason (Z28.2-) names Z28.2-, which includes this code

Code Also 1

These codes say Z28.20 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • Z71.85 Encounter for immunization safety counseling
    if applicable, immunization not carried out (Z28.-) names Z28.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR FAC017
No immunization or underimmunization
Default principal diagnosis: inpatient No · outpatient Yes

Convert Z28.20 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
V64.09 No vaccination NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Z28.20Overview

Is Z28.20 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report immunization not carried out because of patient decision for unspecified reason on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Z28.20 group to?

On inpatient claims, immunization not carried out because of patient decision for unspecified reason maps to MS-DRG 951, 795, with relative weights from 0.2022 to 0.5574 depending on complications. Higher weights mean higher Medicare reimbursement.

Can Z28.20 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because immunization not carried out because of patient decision for unspecified reason describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z28.20 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for immunization not carried out because of patient decision for unspecified reason on inpatient claims. The code appears in the Persons with potential health hazards related to communicable diseases (Z20-Z29) range of the CMS exempt list.

What is the ICD-9 equivalent of Z28.20?

Under the General Equivalence Mappings, immunization not carried out because of patient decision for unspecified reason converts to ICD-9-CM V64.09 (no vaccination NEC). The mapping is approximate, so confirm the match fits the documentation.