All ICD10 Codes
Y09Billable, valid for claims from October 1, 2026

Assault by unspecified means

In Assault (X92-Y09), chapter 20: External Causes of Morbidity

  • Y09 is an unspecified code: use it only when the record doesn't document anything more specific. If the record has more detail, check the other codes under X92-Y09 below.
  • As a secondary diagnosis it is not a CC or MCC, so it doesn't raise the MS-DRG payment.
  • Doesn't count toward a Medicare Advantage risk score (no HCC in V28).
  • 1,231 US deaths in 2024 had an underlying cause in category Y09, per the National Vital Statistics System on CDC WONDER. Death records use WHO ICD-10, so the count is for the whole category.

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Instructional notes

Includes: conditions that are coded here

  • Assassination (attempted) NOS
  • Homicide (attempted) NOS
  • Manslaughter (attempted) NOS
  • Murder (attempted) NOS

Also applies, from Assault (X92-Y09)

These notes sit on X92-Y09 and apply to every code under it, including Y09.

Includes: conditions that are coded here

  • homicide
  • injuries inflicted by another person with intent to injure or kill, by any means

Excludes1: not coded here, use a different code

  • injuries due to legal intervention (Y35.-)
  • injuries due to operations of war (Y36.-)
  • injuries due to terrorism (Y38.-)

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Covers how to report external cause codes (V00-Y99) describing cause, intent, place, activity, and status. They are never principal or first-listed, and reporting is voluntary unless required.

Read Section I.C.20 (page 87), 3 more topics

Other codes under X92-Y09

Assault (X92-Y09)

Y09 MS-DRGs

This code does not group to an MS-DRG as a principal diagnosis.

Related conditions

Grouped by AHRQ's Clinical Classifications Software Refined (CCSR), which sorts every diagnosis code into clinically meaningful categories.

Y09 is in External cause codes: unspecified mechanism (EXT019), with 14 codes. Others in it:

  • R45.88 Nonsuicidal self-harm
  • T14.91XA Suicide attempt, initial encounter
  • X58.XXXA Exposure to other specified factors, initial encounter
  • Y35.899A Legal intervention involving other specified means, unspecified person injured, initial encounter
  • Y35.91XA Legal intervention, means unspecified, law enforcement official injured, initial encounter
  • Y35.92XA Legal intervention, means unspecified, bystander injured, initial encounter
  • Y35.93XA Legal intervention, means unspecified, suspect injured, initial encounter
  • Y35.99XA Legal intervention, means unspecified, unspecified person injured, initial encounter

Y09 is in External cause codes: intent of injury, assault (EXT022), with 485 codes. Others in it:

  • T36.0X3A Poisoning by penicillins, assault, initial encounter
  • T36.1X3A Poisoning by cephalosporins and other beta-lactam antibiotics, assault, initial encounter
  • T36.2X3A Poisoning by chloramphenicol group, assault, initial encounter
  • T36.3X3A Poisoning by macrolides, assault, initial encounter
  • T36.4X3A Poisoning by tetracyclines, assault, initial encounter
  • T36.5X3A Poisoning by aminoglycosides, assault, initial encounter
  • T36.6X3A Poisoning by rifampicins, assault, initial encounter
  • T36.7X3A Poisoning by antifungal antibiotics, systemically used, assault, initial encounter

Other codes that refer to Y09

Notes on these codes point to Y09.

  • W20-W49 Excludes1: assault (X92-Y09)

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.

ICD-9-CM equivalent

Legacy crosswalk from the CMS General Equivalence Mappings (last updated 2018).

  • E968.9 Assault by unspecified means
ICD-9 to ICD-10 converter