What does ICD-10-CM code G40.909 mean?
G40.909 represents Epilepsy, unspecified, not intractable, without status epilepticus. This neurological condition is classified under Chapter 6 (Diseases of the Nervous System) and is commonly encountered in both inpatient and outpatient settings. Coders frequently reference this code as seizure disorder icd 10, seizure disorder unspecified icd 10, unspecified seizure disorder icd 10, or seizure disorder.
Code category and hierarchy
- Chapter: 6 – Diseases of the Nervous System (G00-G99)
- Category: G40
- Code: G40.909 – Epilepsy, unspecified, not intractable, without status epilepticus
Guideline notes and coding considerations
Specificity Warning
G40.909 is an unspecified code. Query the provider for greater specificity when documentation suggests a more precise code is available. Using unspecified codes when specific codes exist may trigger audits.
- Excludes1: conversion disorder with seizures ( F44.5 ); convulsions NOS ( R56.9 ); post traumatic seizures ( R56.1 ); seizure (convulsive) NOS ( R56.9 )
Learn the underlying rules in the ICD-10 Coding Guidelines, Specificity Requirements, Risk Adjustment & MEAT Documentation.
Documentation tips (what coders should confirm)
- Verify the clinical documentation supports the use of G40.909
- Query the provider for greater specificity if clinical details suggest a more precise code
- This is a risk-adjusted diagnosis — ensure annual documentation with MEAT criteria (Monitor, Evaluate, Assess/Address, Treat)
When NOT to use G40.909
Do not assign G40.909 when the clinical scenario involves: conversion disorder with seizures ( F44.5 ); convulsions NOS ( R56.9 ); post traumatic seizures ( R56.1 ); when documentation provides enough detail for a more specific code. Review excludes notes and assign the most specific code supported by documentation.
Audit risk
G40.909 is an unspecified code. Payers and auditors may flag claims with unspecified codes when the medical record contains sufficient detail for a more precise diagnosis. Query the provider for specificity before submitting.
Validate G40.909 Against ICD 10 CM Coding Guidelines
Check this code against official guidelines for conflicts and compliance issues.
Risk adjustment and HCC mapping
HCC Impact
G40.909 (Epilepsy, unspecified, not intractable, without status epilepticus) maps to the following HCC categories: CMS-HCC V24: HCC 79, CMS-HCC V28: HCC 201, RxHCC V08: HCC 164, ESRD V24: HCC 79. Proper documentation using MEAT criteria (Monitor, Evaluate, Assess/Address, Treat) is required for each encounter to support risk-adjusted diagnoses.
Learn more about risk adjustment documentation in our Risk Adjustment & MEAT Documentation Guide.
Related ICD-10 codes
Frequently Asked Questions
The ICD-10-CM code for seizure disorder is G40.909, which represents epilepsy, unspecified, not intractable, without status epilepticus. This code is also commonly referenced as seizure disorder unspecified icd 10, unspecified seizure disorder icd 10, seizure disorder. Verify this code using the ICD Code Auditor to ensure guideline compliance.
Yes. G40.909 is an active ICD-10-CM diagnosis code used to classify epilepsy, unspecified, not intractable, without status epilepticus for clinical documentation, reporting, and medical billing purposes.
Use the ICD Code Auditor to check G40.909 against official ICD-10-CM coding guidelines. The tool validates by fiscal year and patient gender to identify potential conflicts.
G40.909 should be used only when clinical documentation does not provide enough detail for a more specific code. Always query the provider when documentation suggests greater specificity is available, as unspecified codes may trigger audits and impact risk adjustment.
Yes. G40.909 maps to HCC 79 in the CMS-HCC V24 model, and HCC 201 in V28. Accurate coding of this condition directly impacts RAF scores for Medicare Advantage plans. Ensure documentation demonstrates the condition was evaluated and managed during the encounter.
Documentation should clearly describe the clinical condition represented by G40.909 (Epilepsy, unspecified, not intractable, without status epilepticus). Include relevant clinical findings, diagnostic test results, provider assessment, and the treatment plan. The diagnosis must be supported by the medical record and not based solely on lab results without clinical interpretation.
Sources
Reviewed by: Certified ICD-10 Coding & Risk Adjustment Specialist
Learn more about our Clinical Coding Review Process