Skip to main content

Z28.31 ICD-10-CM Code: Underimmunization for COVID-19 status

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Coding at a Glance

Tabular directives
1 inclusion term · 5 use-additional codes · 1 code-also instruction

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for Z28.31 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on Z28.31 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • vaccination not carried out

Source: inherited from Z28

Code Also

Additional codes that may be required to fully describe the encounter.

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

Source: inherited from Z28

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code, if applicable, to identify:
  • immunization not carried out because of contraindication (Z28.0-)
  • immunization not carried out because of patient decision for other and unspecified reason (Z28.2-)
  • immunization not carried out because of patient decision for reasons of belief or group pressure (Z28.1)
  • immunization not carried out for other reason (Z28.8-)

Source: inherited from Z28.3

Coder workflow for Z28.31

MedCoder structured workflow — derived from this code’s own official record

Before you code Z28.31

  1. Z28.31 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewZ28.310, Z28.311

    See the relationships section · Guide: How to choose an ICD-10-CM code →

  2. Confirm the reason for the encounter this Z code records: the circumstance it records. Check whether the code may be reported as first-listed or principal — some Z codes are limited to one position — and do not report a history or status code for a condition documented as current. Z code categories and their reporting positions (Guidelines I.C.21.c, I.C.21.c.15).

    Guide: Z codes as principal or first-listed diagnosis →

Choose the right path

  1. Does the documentation support one of the more specific codes beneath Z28.31?
    Yes → Select that code and continue the checks below on its own page.
    No → Z28.31 cannot be reported as written; query for the specificity its subcategory needs.

    ReviewZ28.310, Z28.311

Consider Z28.31. Then work the Use Additional Code note and review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.
The reason for the encounter
Whether the code records the encounter’s purpose, a status, or a history — and whether it may be first-listed (Guidelines I.C.21.c).

Official instructions as workflow

  • Use Additional Code — after identifying Z28.31(5 notes)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with Z28.31 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewZ28.0, Z28.2, Z28.1, Z28.8

    See the official tabular notes · Guidelines I.A.13

  • Code Also — related condition(1 note)

    Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

    ReviewZ71.85

    See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with Z28.31?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewZ28.0, Z28.2, Z28.1, Z28.8

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Underimmunization for COVID-19 status is a non-billable ICD-10-CM category code (Z28.31). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • Not billable as written — a more specific code is required: Z28.310, Z28.311.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name Z28.31 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Code Also instruction: Z71.85 — Encounter for immunization safety counseling (via Z28.-).

These codes suggest coding this condition alongside when both are present.

Related Codes

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Status”; these codes share that main term but sit in a different category of the Tabular List.

Z17.22 — Progesterone receptor negative status (progesterone receptor, negative), Z17.31 — Human epidermal growth factor receptor 2 positive status (human epidermal growth factor 2 receptor, positive), Z17.32 — Human epidermal growth factor receptor 2 negative status (human epidermal growth factor 2 receptor, negative), Z17.410 — Hormone receptor positive with human epidermal growth factor receptor 2 positive status (combined receptor, positive, hormone receptor positive with human epidermal growth factor receptor 2 positive), Z17.411 — Hormone receptor positive with human epidermal growth factor receptor 2 negative status (combined receptor, positive, hormone receptor positive with human epidermal growth factor receptor 2 negative), Z17.420 — Hormone receptor negative with human epidermal growth factor receptor 2 positive status (combined receptor, negative, hormone receptor negative with human epidermal growth factor receptor 2 positive), Z17.421 — Hormone receptor negative with human epidermal growth factor receptor 2 negative status (combined receptor, negative, hormone receptor negative with human epidermal growth factor receptor 2 negative), Z19.1 — Hormone sensitive malignancy status (malignancy, hormone sensitive), Z19.2 — Hormone resistant malignancy status (malignancy, hormone resistant), Z21 — Asymptomatic human immunodeficiency virus [HIV] infection status (human immunodeficiency virusinfection, asymptomatic), Z33.1 — Pregnant state, incidental (pregnancy, incidental), Z39.0 — Encounter for care and examination of mother immediately after delivery (postpartum, care immediately after delivery), Z39.2 — Encounter for routine postpartum follow-up (postpartum), Z56.82 — Military deployment status (deployment), Z66 — Do not resuscitate (do not resuscitate), Z74.01 — Bed confinement status (bed confinement), Z76.82 — Awaiting organ transplant status (awaiting organ transplant), Z78.1 — Physical restraint status (physical restraint), Z87.890 — Personal history of sex reassignment (sex reassignment surgery status), Z90.02 — Acquired absence of larynx (laryngectomy), +77 more

Contextual Map

Every relationship of Z28.31 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run Z28.31 with this related code in Claim Check

Hierarchy

Referenced by Code Also instructions

Nearest codes (22)

Change history

Relevant guides

Common coding questions

Can Z28.31 be billed directly?

No. Z28.31 (Underimmunization for COVID-19 status) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "Z28.31 — Underimmunization for COVID-19 status." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/z28.31-underimmunization-for-covid-19-status

Change history

  • FY2022 — October 1, 2021
    Added to the code set
    Underimmunization for COVID-19 status
    FY2022 changes

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Z28.31 in its code family, with their registry titles.

View all codes in the Z28 family