External Cause Status Coding (Y99)

by  Wyn Staheli, Director of Content - innoviHealth
Apr 1st, 2020 - Reviewed/Updated Apr 27th

External cause codes are found in Chapter 20: External Causes of Morbidity (V00-Y99) of the Tabular List. They are secondary codes intended to provide data for injury research and evaluation of injury prevention strategies. Mandatory reporting of these codes is not required by all payers and even when they are required, it might only be in certain situations (e.g., drug overdose, personal injury). 

External cause codes identify:

• How the injury or health condition happened (cause),
• The intent (unintentional or accidental; or intentional, such as suicide or assault),
• The place where the event occurred,
• The activity of the patient at the time of the event, and
• The person’s status (e.g. civilian, military)

Although there is no national requirement for mandatory external cause code reporting, voluntary reporting is encouraged. Be aware of individual state or payer requirements which may mandate their use. It may be helpful to review the chapter specific guidelines for external cause codes found in Section 1.C.20 of the ICD-10-CM Official Coding Guidelines 1.C.20.k (See References below). Also, there are several guidelines and definitions are also listed at the beginning of Chapter 20 within the Tabular List. A review of these rules is essential for a complete understanding of external cause code reporting.

Tip: When providers add these codes to a claim, it allows third parties to obtain information directly from the claim itself, without needing to review the medical records.

External Cause Coding Tips

The following are some pointers for coding from category Y99- External Cause Status:

• When applicable, a code from category Y99- should be assigned whenever any other external cause or activity (e.g., Y93-) code is assigned for an encounter. External cause status codes indicate work status and include:

Y99.0 Civilian activity done for income or pay
Y99.1 Military activity
Y99.2 Volunteer activity
Y99.8 Other external cause status

• Do not assign a code from category Y99- in the case of:
• Poisonings
• Adverse effects
• Misadventures
• Late effects
• An external cause status code is used only once, at the initial encounter for treatment.
• Only one code from category Y99- should be recorded on a medical record.
• If the status is not stated, do not assign Y99.9 “Unspecified external cause status.”