R51.9 ICD-10-CM Code: Headache, unspecified
R51.9 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · free HCC coding tools
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FY 2026 Apr update / Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99) / General symptoms and signs (R50-R69)
R51.9
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceHeadache, unspecified
A headache where the specific type, location, or cause is not documented or identified.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
Official- Facial pain NOS
Excludes 2
Official- abnormal findings on antenatal screening of mother (O28.-)Inherited from R00-R99, R51
- certain conditions originating in the perinatal period (P04-P96)Inherited from R00-R99, R51
- signs and symptoms classified in the body system chaptersInherited from R00-R99, R51
- signs and symptoms of breast (N63, N64.5)Inherited from R00-R99, R51
- atypical face pain (G50.1)Inherited from R00-R99, R51
- migraine and other headache syndromes (G43-G44)Inherited from R00-R99, R51
- trigeminal neuralgia (G50.0)Inherited from R00-R99, R51
Related Codes
Includes
OfficialNo Includes notes are included in this display for R51.9. Check the code and parent instructions in the Code Book.
Excludes 1
OfficialNo Excludes 1 notes are included in this display for R51.9. Check the code and parent instructions in the Code Book.
Code First
OfficialNo Code First sequencing instructions are included in this display for R51.9. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for R51.9. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for R51.9. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is R51.9 an HCC code?
No. R51.9 is a billable ICD-10-CM code with no mapping under the current CMS-HCC V28 community payment model, and none under the ESRD, Part D RxHCC, or HHS-HCC models.
- Code
- R51.9
- Description
- Headache, unspecified
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF reference coefficient
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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What This Code Means
R51.9 is the ICD-10-CM diagnosis code for headache, unspecified. A headache where the specific type, location, or cause is not documented or identified. R51.9 sits in the ICD-10-CM chapter for symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (r00-r99), within the section covering general symptoms and signs (r50-r69).
R51.9 is a billable ICD-10-CM code, but no current CMS-HCC V28 community payment mapping is shown, and none under the ESRD, Part D RxHCC, or HHS-HCC models. Do not assign risk adjustment value from this page when no source-backed mapping is shown; verify the applicable model and payment year.
This is a non-specific code; attempt to obtain more detailed information about headache characteristics from the provider.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for R51.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.