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Y99 ICD-10-CM Code: External cause status

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

Coder workflow for Y99

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

Before you code Y99

  1. Y99 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).

    ReviewY99.0, Y99.1, Y99.2, Y99.8, Y99.9

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

  2. An external cause code is reported in addition to the code for the injury or condition, never as the principal or first-listed diagnosis. Confirm the cause, intent, place of occurrence, activity and status where the record documents them, and assign the 7th character that matches the injury code. External cause coding guidelines (Guidelines I.C.20.a).

Choose the right path

  1. Does the documentation support one of the more specific codes beneath Y99?
    Yes → Select that code and continue the checks below on its own page.
    No → Y99 cannot be reported as written; query for the specificity its subcategory needs.

    ReviewY99.0, Y99.1, Y99.2, Y99.8, Y99.9

Consider Y99. Then 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).

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

External cause status is a non-billable ICD-10-CM category code (Y99). 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.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Chapter 20: External Causes of Morbidity (V00-Y99)

k. External Cause Status A code from category Y99, External cause status, should be assigned whenever any other external cause code is assigned for an encounter, including an Activity code, except for the events noted below. Assign a code from category Y99, External cause status, to indicate the work status of the person at the time the event occurred. The status code indicates whether the event occurred during military activity, whether a non-military person was at work, whether an individual including a student or volunteer was involved in a non-work activity at the time of the causal event.

Chapter 20: External Causes of Morbidity (V00-Y99)

A code from Y99, External cause status, should be assigned, when applicable, with other external cause codes, such as transport accidents and falls. The external cause status codes are not applicable to poisonings, adverse effects, misadventures or late effects.

Chapter 20: External Causes of Morbidity (V00-Y99)

Do not assign a code from category Y99 if no other external cause codes (cause, activity) are applicable for the encounter.

Chapter 20: External Causes of Morbidity (V00-Y99)

An external cause status code is used only once, at the initial encounter for treatment. Only one code from Y99 should be recorded on a medical record.

Verify Before Coding

  • Not billable as written — a more specific code is required: Y99.0, Y99.1, Y99.2, Y99.8, Y99.9.
  • Principal-diagnosis restriction. External cause of morbidity codes (V, W, X and Y) describe the circumstance that caused an injury, not the condition treated. The Medicare Code Editor rejects them as a principal diagnosis; sequence the injury or condition first and report this code as secondary.

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

Contextual Map

Every relationship of Y99 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.

Hierarchy

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Common coding questions

Can Y99 be billed directly?

No. Y99 (External cause 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 FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 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. "Y99 — External cause status." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/y99-external-cause-status

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    External cause status

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Y99 in its code family, with their registry titles.