ICD-10 R99
Billable / SpecificIll-defined and unknown cause of mortality
About ICD-10-CM R99
ICD-10-CM code R99 represents Ill-defined and unknown cause of mortality. This is a billable/specific code in the Symptoms, Signs, and Abnormal Findings chapter (block R99). The 2026 edition of ICD-10-CM R99 became effective on October 1, 2025.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under R99. Per CMS ICD-10-CM Tabular 2026.
- Death (unexplained) NOS
- Unspecified cause of mortality
Medicare LCD Coverage for R99
Local Coverage Determinations (LCDs) from CMS MACs that list R99 as a covered diagnosis.
This doesn't mean the code isn't covered, it means no MAC has issued a Local Coverage Determination naming this specific code. Coverage may still apply under National Coverage Determinations or general medical-necessity rules.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing R99.
Our payer policy database covers Aetna, Cigna, Anthem, BCBS, Humana, and Medicare Advantage plans, but R99 doesn't currently appear in any indexed policy. The code may still be covered under standard plan benefits.
CPT Codes Commonly Billed with R99
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert R99 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| R99 | 7980 | 10000 |
| R99 | 7999 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
ICD-10 R99, Billing FAQ
Is ICD-10 code R99 billable? +
Yes, R99 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to R99? +
ICD-10 R99 includes: Death (unexplained) NOS; Unspecified cause of mortality.
What ICD-9 codes does R99 map to? +
Per CMS GEMs, R99 maps to ICD-9 codes: 7980, 7999. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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