Z23 — Encounter for immunization

Z23

ICD-10 Chapter 21: Factors Influencing Health Status — illustrative image — Chapter 21: Factors influencing health status and contact with health services (Z00–Z99) — illustrative image

What this code means

An encounter at which a vaccine is given (immunisation), regardless of the vaccine type.

Also called: immunization, vaccination encounter.

When this code is used

Used for encounter for immunisation.

Where it sits in ICD-10-CM

Code Z23 belongs to Chapter 21: Factors influencing health status and contact with health services, which covers codes Z00–Z99 in the FY2027 ICD-10-CM tabular list. The official description above is copied verbatim from the CDC/NCHS FY2027 code file.

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Frequently asked questions

What is ICD-10-CM code Z23?

Z23 is the ICD-10-CM diagnosis code for “Encounter for immunization”. An encounter at which a vaccine is given (immunisation), regardless of the vaccine type.

When is code Z23 used?

Used for encounter for immunisation. It belongs to Chapter 21 of ICD-10-CM (Factors influencing health status and contact with health services).

This guide explains ICD-10-CM codes in plain language for patients, students and other readers. It is educational information only — not coding, billing or medical advice. The code recorded for any real encounter is assigned from the full clinical documentation by the treating team and qualified coders, and only they can decide which code fits a specific case.