Z28 vs Z71.85

Z28 (Immunization not carried out and underimmunization status) compared with Z71.85 (Encounter for immunization safety counseling), from the official CMS tabular data.

Summary

These codes may both be needed to describe one condition, because Z28 carries a Code Also note covering Z71.85.

Official rule

What is different?

The conditions named and billing status.Z28 is “Immunization not carried out and underimmunization status”; Z71.85 is “Encounter for immunization safety counseling”. Z28 is a non-billable header; Z71.85 is billable.

Registry fact

Can these codes be reported together?

Yes, and both may be needed.Z28 carries a Code Also note covering Z71.85: “, if applicable, encounter for immunization safety counseling (Z71.85)”. The two may both be required to fully describe the condition; the note states no sequencing order.

Official ruleGuide: Code First vs Use Additional Code vs Code Also

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. Z71.85 carries 1 Excludes1 note covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code. Z71.85 carries 3 Excludes2 notes covering other codes; the side-by-side table quotes them.

Official rule

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

One is a header.Z28 is a non-billable header, but Z71.85 is not one of its subdivisions.

Registry fact

Are there sequencing instructions?

No order is given.The Code Also note linking them states no sequencing order; sequence by the reason for the encounter.

Official ruleGuide: Code First vs Use Additional Code vs Code Also

Are there other coding relationships?

Yes.Both codes may be needed together. Z28 carries a Code Also note covering Z71.85: “, if applicable, encounter for immunization safety counseling (Z71.85)”

Official ruleGuide: Code First vs Use Additional Code vs Code Also

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Code Also relationship

Z28

Immunization not carried out and underimmunization status

↔

Z71.85

Encounter for immunization safety counseling

What we found

Both codes may be needed together.Z28 carries a Code Also note covering Z71.85: “, if applicable, encounter for immunization safety counseling (Z71.85)”

A Code Also note means the two codes may both be required to fully describe the condition. CMS states no sequencing order for it — sequence by the reason for the encounter.

What to review

Report both when both are needed to describe the condition, sequenced by the reason for the encounter.

Guide: Code First vs Use Additional Code vs Code Also Check these on a claim

Why it matters

A "Code Also" note means two codes may be required together, but the Guidelines state no sequencing order for it -- sequence by the reason for the encounter, not by this relationship.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

Section I.A.17 — “Code also ” note · applies to: Code also
A “code also” note instructs that two codes may be required to fully describe a condition, but this note does not provide sequencing direction. The sequencing depends on the circumstances of the encounter.
ICD-10-CM Official Guidelines FY2026

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

	Z28Immunization not carried out and underimmunization status	Z71.85Encounter for immunization safety counseling
Billing status	Non-billable header Report instead: Z28.01, Z28.02, Z28.03, Z28.04, Z28.09	Billable
Classification	Z00-Z99 — Factors Influencing Health Status and Contact with Health Services (Z00-Z99)	Z00-Z99 — Factors Influencing Health Status and Contact with Health Services (Z00-Z99)
Definition	Immunization not carried out and underimmunization status is a non-billable ICD-10-CM category code (Z28).	Encounter for immunization safety counseling is a billable ICD-10-CM diagnosis code (Z71.85).
Includes	vaccination not carried out	Encounter for vaccine product safety counseling
Excludes1	—	encounter for health counseling related to travel (Z71.84)
Excludes2	—	counseling for contraception (Z30.0-) contraceptive or procreation counseling (Z30-Z31) sex counseling (Z70.-)
Code also	, if applicable, encounter for immunization safety counseling (Z71.85)	, if applicable, encounter for immunization (Z23) , if applicable, immunization not carried out (Z28.-)

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.

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Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources