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ICD-10-CM G47.12: Idiopathic hypersomnia without long sleep time

G47.12 is the billable ICD-10-CM code for idiopathic hypersomnia without long sleep time, in category G47 (Sleep disorders) of the Episodic and paroxysmal disorders section. As a principal diagnosis it groups to MS-DRG 887 Other Mental Disorder Diagnoses (MDC 19 MDC 19: Mental Diseases and Disorders). 9 LCD billing and coding articles list it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
G47.12
billable FY2027 ICD-10-CM code
Category
G47 Sleep disorders
Chapter
6: Diseases of the nervous system (G00-G99)
CC/MCC (MS-DRG v44)
Neither
CMS-HCC V28
Not mapped
POA reporting
Required

Tabular list notes for G47.12

The tabular list has no notes on G47.12 itself; the notes below apply from its parent headings.

Inherited from G47 (Sleep disorders)

Excludes2 (not part of this condition, may be coded together)
  • nightmares (F51.5)
  • nonorganic sleep disorders (F51.-)
  • sleep terrors (F51.4)
  • sleepwalking (F51.3)

Inherited from G47.1 (Hypersomnia)

Excludes2 (not part of this condition, may be coded together)
  • 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)
  • sleep apnea (G47.3-)

MS-DRG grouping when G47.12 is the principal diagnosis

MS-DRG v44 groups for G47.12 as principal diagnosis
MDCMS-DRGs
19 MDC 19: Mental Diseases and Disorders887

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for G47.12 shows the full grouping logic.

CC/MCC status and inpatient edits

G47.12 is neither a CC nor an MCC under MS-DRG v44, so as a secondary diagnosis it does not raise the MS-DRG severity level. Check G47.12 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.

CMS-HCC V28 risk adjustment

G47.12 does not map to a payment HCC in the PY2027 CMS-HCC V28 model, so on its own it does not change a Medicare Advantage risk score.

LCD billing and coding articles that list G47.12

9 current Medicare billing and coding articles list G47.12 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM G47.12 mean?

G47.12 means idiopathic hypersomnia without long sleep time. It is one of 25 billable codes under G47, sleep disorders.

Which MS-DRG does G47.12 group to?

As the principal diagnosis, G47.12 groups to MS-DRG 887 Other Mental Disorder Diagnoses (MDC 19 MDC 19: Mental Diseases and Disorders) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.