Y99 – External cause status
ICD-10-CM 2027 diagnosis code · Supplementary factors related to causes of morbidity classified elsewhere
ICD-10-CM code
Y99
- Code
Y99(claims format:Y99)- Description
- External cause status
- Billable
- No – use a more specific code below
- Valid for
- Dates of service October 1, 2026 – September 30, 2027 (FY2027)
- Chapter
- 20. External causes of morbidity (V00-Y99)
- Block
- Y90-Y99 Supplementary factors related to causes of morbidity classified elsewhere
Billable codes under Y99
Y99 is a header code and cannot be used on claims. Choose the most specific code:
- Y99.0 – Civilian activity done for income or payBillable
- Y99.1 – Military activityBillable
- Y99.2 – Volunteer activityBillable
- Y99.8 – Other external cause statusBillable
- Y99.9 – Unspecified external cause statusBillable
Notes for Y99
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.
Notes inherited from parent codes
Instructional notes at a category or block level apply to every code below it.
Block Y90-Y99
Notes:
- These categories may be used to provide supplementary information concerning causes of morbidity. They are not to be used for single-condition coding.
Frequently asked questions
What is ICD-10 code Y99?
Y99 is the ICD-10-CM code for external cause status, in the block Y90-Y99 (Supplementary factors related to causes of morbidity classified elsewhere).
Is Y99 a billable code?
No. Y99 is a header code with more specific child codes; report one of the billable codes listed above.
Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.