G47.12 ICD-10-CM Code: Idiopathic hypersomnia without long sleep time
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Episodic and paroxysmal disorders (G40-G47)
G47.12
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceIdiopathic hypersomnia without long sleep time
Excessive daytime sleepiness and fatigue without the characteristic long sleep periods seen in other forms of idiopathic hypersomnia.
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
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for G47.12 in this effective period.
Excludes 2
Official- alcohol-related hypersomnia (F10.182, F10.282, F10.982)
- drug-related hypersomnia (F11.182, F11.282, F11.982, F13.182, F13.282, F13.982, F14.182, F14.282, F14.982, F15.182, F15.282, F15.982, F19.182, F19.282, F19.982)
- hypersomnia due to a mental disorder (F51.13)
- hypersomnia not due to a substance or known physiological condition (F51.1-)
- primary hypersomnia (F51.11)
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for G47.12 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for G47.12 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for G47.12 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G47.12 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G47.12 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 G47.12 an HCC code?
No. G47.12 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
G47.12 is the ICD-10-CM diagnosis code for idiopathic hypersomnia without long sleep time. Excessive daytime sleepiness and fatigue without the characteristic long sleep periods seen in other forms of idiopathic hypersomnia. G47.12 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).
G47.12 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.
Confirm that sleep duration is normal but daytime somnolence is present.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G47.12 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm that sleep duration is normal but daytime somnolence is present
- •Differentiate from G47.11 by absence of prolonged nocturnal sleep