ICD-10 G40.804
Billable / Specific HCC v28: 79 CCOther epilepsy, intractable, without status epilepticus
About ICD-10-CM G40.804
ICD-10-CM code G40.804 represents Other epilepsy, intractable, without status epilepticus. This is a billable/specific code in the Nervous System chapter (block G40). The 2026 edition of ICD-10-CM G40.804 became effective on October 1, 2025.
Coding Tips for G40.804
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
G40.804 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.
G40.804 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC 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, CC
codes Other epilepsy, intractable, without status epilepticus. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for G40.804
Local Coverage Determinations (LCDs) from CMS MACs that list G40.804 as a covered diagnosis.
Showing top 10 of 481 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G40.804.
4 Cigna
5 Medicare
CPT Codes Commonly Billed with G40.804
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- G0252 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- 78608 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- A9597 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- A9601 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- G0235 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- 78609 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- A9552 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- G0219 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- A9598 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- 95711 CMS LCD: Billing and Coding: EEG � Ambulatory Monitoring CMS LCD
Convert G40.804 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 |
|---|---|---|
| G40.804 | 34581 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To G40.804
Other codes in section G40-G47 (Episodic and paroxysmal disorders).
ICD-10 G40.804, Billing FAQ
Is ICD-10 code G40.804 billable? +
Yes, G40.804 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does G40.804 affect Medicare Advantage HCC risk adjustment? +
Yes. G40.804 maps to CMS-HCC v28 category 79. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is G40.804 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with G40.804? +
Procedures frequently paired with G40.804 include: G0252, 78608, A9597, A9601, G0235.
What ICD-9 codes does G40.804 map to? +
Per CMS GEMs, G40.804 maps to ICD-9 codes: 34581. Useful for legacy data review and historical claim analysis.
Get the full PayerReady toolkit
Free access to CPT/ICD-10 lookup, denial appeals, fee comparator, and claim auditing with credentialing enrollment.
Start free →Run this code through our claim audit tool
Check NCCI bundling, MUE limits, and modifier logic before submission.
Try the auditor →Did this page help?
Quick signal so we know what to improve.
If you want a code reference page that doesn't exist yet, email coding@payerready.com.
Tell us what's missing or wrong: coding@payerready.com. We respond within 5 business days.
Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
Powered by 11K CPT · 98K ICD-10 · 860K MPFS rates · 4.5M NCCI edits · 9.5M NPIs. Our data methodology · About our coding team