ICD-10 G40.301
Billable / Specific HCC v28: 79 MCCGeneralized idiopathic epilepsy and epileptic syndromes, not intractable, with status epilepticus
About ICD-10-CM G40.301
ICD-10-CM code G40.301 represents Generalized idiopathic epilepsy and epileptic syndromes, not intractable, with status epilepticus. This is a billable/specific code in the Nervous System chapter (block G40). The 2026 edition of ICD-10-CM G40.301 became effective on October 1, 2025.
Coding Tips for G40.301
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
G40.301 is a CMS-HCC v28 risk-adjustment code (category 79). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
G40.301 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Inpatient DRG Impact, MCC
codes Generalized idiopathic epilepsy and epileptic syndromes, not intractable, with status epilepticus. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for G40.301
Local Coverage Determinations (LCDs) from CMS MACs that list G40.301 as a covered diagnosis.
Showing top 10 of 613 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G40.301.
2 Cigna
5 Medicare
CPT Codes Commonly Billed with G40.301
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 95819 EEG awake and asleep — epilepsy, generalized seizures, absence seizures, focal seizures, seizure NOS, fasciculations, syncope, encephalopathy, cognitive decline, aphasia, migraine, headache, insomnia Neurology
- G0480 CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
- 80306 CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
- G0482 CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
- 0603U CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
- 80305 CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
- G0659 CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
- G0483 CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
- 80307 CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
- G0481 CMS LCD: Billing and Coding: Urine Drug Testing CMS LCD
Convert G40.301 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 |
|---|---|---|
| G40.301 | 3453 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To G40.301
Other codes in section G40-G47 (Episodic and paroxysmal disorders).
ICD-10 G40.301, Billing FAQ
Is ICD-10 code G40.301 billable? +
Yes, G40.301 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does G40.301 affect Medicare Advantage HCC risk adjustment? +
Yes. G40.301 maps to CMS-HCC v28 category 79. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is G40.301 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with G40.301? +
Procedures frequently paired with G40.301 include: 95819, G0480, 80306, G0482, 0603U.
What ICD-9 codes does G40.301 map to? +
Per CMS GEMs, G40.301 maps to ICD-9 codes: 3453. 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 July 16, 2026.
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