G44.001 ICD-10-CM Code: Cluster headache syndrome, unspecified, intractable
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Episodic and paroxysmal disorders (G40-G47)
G44.001
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceCluster headache syndrome, unspecified, intractable
Severe, recurring headaches that occur in clusters (grouped episodes) and do not respond adequately to standard treatment, with unspecified pattern.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
Code Trumping
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Code Book Path
Inclusion Terms
Official- Ciliary neuralgia
- Cluster headache NOS
- Histamine cephalgia
- Lower half migraine
- Migrainous neuralgia
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for G44.001 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for G44.001 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for G44.001 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for G44.001 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G44.001 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G44.001 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is G44.001 an HCC code?
No. G44.001 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
G44.001 is the ICD-10-CM diagnosis code for cluster headache syndrome, unspecified, intractable. Severe, recurring headaches that occur in clusters (grouped episodes) and do not respond adequately to standard treatment, with unspecified pattern. G44.001 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering episodic and paroxysmal disorders (g40-g47).
G44.001 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Document the cluster pattern, including frequency and duration of cluster periods.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G44.001 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the cluster pattern, including frequency and duration of cluster periods
- •Intractability requires evidence of failed treatment attempts; differentiate from episodic vs. chronic patterns