R99Billable
Ill-defined and unknown cause of mortality
- Chapter
- 18. Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
- Category
- R99
- Effective date
- October 1, 2026
Frequently asked questions
What is ICD-10 code R99?
R99 is an ICD-10-CM diagnosis code for Ill-defined and unknown cause of mortality.
Is R99 a billable code?
Yes. R99 is billable and specific enough to be used on a claim.
What ICD-10-CM chapter is R99 in?
R99 falls under Chapter 18: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified.
When did R99 become effective?
R99 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.