Y99
External cause status
Y99 is a non-billable ICD-10-CM code category for external cause status. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are Y99.0 Civilian activity done for income or pay, Y99.1 Military activity, Y99.2 Volunteer activity, Y99.8 Other external cause status and 1 more.
Guidelines tips
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
An external cause code is never a principal or first-listed diagnosis. Its 7th character is assigned for each encounter and should match the injury or condition code.
Only one Y99 code is recorded, at the initial encounter. It does not apply to poisonings, adverse effects, misadventures or late effects, and Y99.9 is not used when the status is not stated.
Notes
- A single code from category Y99 should be used in conjunction with the external cause code(s) assigned to a record to indicate the status of the person at the time the event occurred.
Also from chapter/block level (2 notes)
- These categories may be used to provide supplementary information concerning causes of morbidity. They are not to be used for single-condition coding.
- This chapter permits the classification of environmental events and circumstances as the cause of injury, and other adverse effects. Where a code from this section is applicable, it is intended that it shall be used secondary to a code from another chapter of the Classification indicating the nature of the condition. Most often, the condition will be classifiable to Chapter 19, Injury, poisoning and certain other consequences of external causes (S00-T88). Other conditions that may be stated to be due to external causes are classified in Chapters I to XVIII. For these conditions, codes from Chapter 20 should be used to provide additional information as to the cause of the condition.