2025 ICD-10-CM code Y99
(Active) Effective Date: N/A External causes of morbidity - Supplementary factors related to causes of morbidity classified elsewhere 20 Feed
External cause status. This code indicates the status of the person at the time the event occurred.
The Y99 code is used to provide additional information about the circumstances of the injury or illness and is not directly related to medical necessity.
In simple words: This code provides additional information about the circumstances surrounding an injury or illness.
External cause status. 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.
Example 1: A patient falls while hiking and sustains a fracture. The Y99 code would be used in addition to the fracture code to indicate the patient's status as a hiker at the time of the fall., A construction worker is injured on the job. The Y99 code is used to specify their status as a worker, alongside the injury code., A passenger in a car accident is injured. Y99 helps classify their status as a passenger, supplementing the injury code.
Documentation should clearly state the person's status at the time of the event.
** While there is no national mandate for reporting external cause codes, including Y99, providers are encouraged to report them voluntarily as they provide valuable data for injury research and prevention.