• January 29, 2026

ICD 10 Epilepsy 2026: G40 Billing & CMS Guidelines

ICD 10 Epilepsy 2026 G40 Billing & CMS Guidelines

What Is Epilepsy? 

Epilepsy is a chronic brain disorder caused by abnormal electrical activity in the brain that leads to recurring seizures. It is diagnosed through clinical evaluation, patient history, and supporting tests such as EEG or brain imaging. 

What Is ICD 10 Epilepsy? 

ICD 10 Epilepsy is how epilepsy is recorded in the ICD-10-CM coding system. Doctors use it to name the condition. Insurers use it to judge claims. It tells reviewers that seizures are part of a chronic disorder, not a one-time event. 

Introduction

ICD 10 Epilepsy shapes how care is paid, reviewed, and trusted. When the code fits the clinical record, claims move forward. When it does not, delays begin. 

This guide answers the questions that matter most. Which epilepsy codes exist? Why do they matter? How should they be used correctly? 

What Is the ICD 10 Code for Epilepsy?

There is no single ICD 10 code for epilepsy. ICD 10 Epilepsy uses a family of codes because epilepsy does not look the same in every patient. 

Some seizures start in one part of the brain. Others involve the whole brain. Some respond well to treatment. Others do not. ICD-10 reflects these differences, so the diagnosis matches reality. 

This distinction matters because insurance payers do not pay for vague diagnoses. They pay for clearly defined conditions. CMS requires diagnosis coding to reflect what is known and documented at the time of care. 

If the provider has confirmed epilepsy, the code must show that. 

Epilepsy codes are found under the G40 category in ICD-10-CM. Each code communicates how the epilepsy behaves, not just that it exists. 

ICD 10 Epilepsy Codes List (G40 Category)

ICD-10 Code Code Meaning When It Is Used
G40.0 Localization-related (focal) epilepsy Seizures start in one specific area of the brain
G40.1 Localization-related epilepsy, intractable Focal seizures that do not respond to standard treatment
G40.2 Generalized epilepsy Seizures involve both sides of the brain
G40.3 Generalized idiopathic epilepsy Generalized seizures with no identified underlying cause
G40.4 Other generalized epilepsy Generalized epilepsy not fitting standard classifications
G40.5 Special epileptic syndromes Rare or well-defined epilepsy syndromes
G40.6 Grand mal seizures, unspecified Older terminology still appearing in medical records
G40.7 Petit mal status epilepticus Continuous or recurrent absence-type seizures
G40.8 Other epilepsy Epilepsy types not classified elsewhere
G40.9 Epilepsy, unspecified Epilepsy confirmed but insufficient documentation for specificity

The G40 codes shown above represent code categories. For billing purposes, ICD-10-CM requires additional digits to identify intractability and status epilepticus. Final claim submission typically uses 6-character codes, such as G40.909, based on provider documentation. 

ICD 10 Epilepsy Codes With 2026 Billing Context

ICD 10 Code Code Meaning 2026 Billing Status
G40.309 Generalized idiopathic epilepsy, not intractable Billable code when the epilepsy diagnosis and generalized seizure type are clearly documented
G40.911 Epilepsy, unspecified, intractable, with status epilepticus High-severity billable code; requires documentation of medication resistance and status epilepticus
G40.019 Localization-related (focal) epilepsy, intractable Billable for ongoing epilepsy management when intractability is clinically supported

Using G40.9 may be acceptable early. As more information becomes available, the code should become more specific. This progression shows accurate care and proper reporting. 

Why Does ICD 10 Epilepsy Coding Matter for Billing?

Billing systems rely on diagnosis codes. ICD 10 Epilepsy explains why care continues beyond a single visit. It supports testing, follow-ups, and long-term treatment. 

When coding and documentation align, claims process faster. When they do not, CMS flags mismatches. Reviews increase. Payments slow. 

Accurate coding protects revenue and compliance. 

What Are Common ICD 10 Epilepsy Coding Mistakes?

Most ICD 10 Epilepsy coding errors do not happen because rules are unclear. They happen because old habits stay in place even when the clinical picture changes. When coding does not keep up with the provider’s documentation, claims become weak and review risk increases. 

These mistakes often appear small. In reality, they shape how payers judge medical necessity and accuracy. Recognizing them early helps prevent delays, denials, and audit questions. 

Common mistakes 

  • Using seizure symptom codes after epilepsy is confirmed 
  • Keeping unspecified codes when details are available 
  • Coding epilepsy without a clear diagnosis statement 

Each of these mistakes sends the wrong message to reviewers. When codes do not reflect what the provider has actually diagnosed, claims lose support. 

What Is the Difference Between Seizure ICD 10 Codes and ICD 10 Epilepsy Codes?

This difference matters at the coding level. Seizure codes and epilepsy codes send very different messages to payers, auditors, and billing systems. The table below shows the distinction clearly and quickly. 

Seizure vs. Epilepsy: ICD-10 Comparison

Feature Seizure ICD-10 Codes (e.g., R56.9) ICD-10 Epilepsy Codes (G40 Category)
Medical meaning A single symptom or isolated seizure event A chronic neurological disorder
Underlying cause Often temporary, such as fever, stress, or metabolic imbalance Recurrent, unprovoked abnormal electrical activity in the brain
ICD-10 chapter Symptoms and Signs (R-codes) Diseases of the Nervous System (G-codes)
Billing message Indicates treatment of an acute or one-time event Indicates management of a long-term condition
Documentation use Used for first-time seizures or diagnostic evaluation visits Used once epilepsy is confirmed by the provider

Why This Distinction Protects Your Revenue

Medical necessity 

Many insurance payers will not approve long-term treatment, advanced EEG testing, or ongoing anti-epileptic therapy when a claim only lists a seizure symptom code. They require an epilepsy diagnosis from the G40 category to justify continued care. This aligns with review standards used by the Centers for Medicare & Medicaid Services. 

Audit defense 

Audit teams watch for symptom codes that remain on a patient record for too long. When seizure codes are used repeatedly without progression to ICD 10 Epilepsy after diagnosis, records may be flagged for lack of diagnostic clarity under CMS audit logic. 

The intractable factor 

Medication-resistant epilepsy cannot be captured using seizure symptom codes. Severity and treatment resistance can only be reflected through ICD 10 Epilepsy codes within the G40 category. Missing this transition often leads to missed reimbursement. 

Seizure codes describe what happened. ICD 10 Epilepsy codes describe what is being managed. That distinction is critical for accurate billing, compliance, and revenue protection. 

What Documentation Is Required for ICD 10 Epilepsy?

Accurate ICD 10 Epilepsy coding starts with documentation. Codes do not stand alone. They rely on what the provider clearly records in the medical note. When documentation is strong, coding is clear. When it is weak, claims become vulnerable. 

Before selecting a code, a short review process helps keep decisions accurate and defensible. 

Best practice steps 

  • Read the diagnosis statement carefully 
  • Confirm epilepsy is clearly named 
  • Select the code that matches the documentation 

No assumptions. No shortcuts. 

Documentation Elements for ICD 10 Epilepsy

Documentation Element Purpose
Diagnosis statement Confirms that epilepsy has been formally diagnosed
Seizure history Demonstrates ongoing or recurrent seizure activity
Care plan Supports continued treatment, monitoring, and follow-up
Specificity (focal vs. generalized) Required to code beyond unspecified epilepsy (G40.9)

Clear documentation supports accurate ICD 10 Epilepsy coding, reduces review risk, and helps protect reimbursement over time. 

2026 ICD 10 Epilepsy Coding Updates

As of 2026, the G40 category remains the correct coding range for ICD 10 Epilepsy. There are no major structural changes to the epilepsy codes themselves. What has changed is how CMS and the AMA expect these codes to be supported in documentation, especially in digital and remote care settings. 

Increased focus on the intractable status

In 2026, reviewers are paying closer attention to epilepsy coded as intractable. Providers are expected to document which anti-epileptic medications were tried, how long they were used, and why they failed. Without this detail, intractable epilepsy codes may not hold up during review.

Social determinants of health documentation

There is growing emphasis on linking ICD 10 Epilepsy with Social Determinants of Health when they affect seizure control. Issues such as difficulty accessing medication, transportation barriers, or unstable housing should be documented when relevant. This helps explain why epilepsy may remain uncontrolled despite treatment. 

Telehealth documentation expectations

For neurology visits performed through telehealth, 2026 guidance stresses that diagnostic detail must still be present. Even when seizures are not observed in person, documentation should clearly describe seizure type based on patient history. Loss of specificity during telehealth visits is a common review risk.

Why this matters now

These updates reflect how epilepsy claims are reviewed today. Accurate coding in 2026 depends less on new codes and more on clear, complete documentation that explains severity, treatment response, and ongoing risk.

What Are the Key Takeaways for ICD 10 Epilepsy Coding?

Epilepsy must be clearly stated and supported in the medical record before epilepsy codes are used. 

Key takeaways 

  • Code epilepsy only when the provider clearly diagnoses it 
  • Use the G40 category to reflect epilepsy as a chronic condition 
  • Start with unspecified codes only when details are not yet available 
  • Move to specific codes once seizure type is documented 
  • Do not continue seizure symptom codes after epilepsy is confirmed 
  • Ensure documentation supports ongoing care and follow-up 

Following these principles keeps coding consistent with CMS expectations and AMA guidance. When ICD 10 Epilepsy coding matches the clinical record, the claims process is faster, audit risk decreases, and reimbursement remains protected. 

Frequently Asked Questions: ICD 10 Epilepsy 2026

What is the ICD 10 code for epilepsy?

The primary ICD 10 code for epilepsy is the G40 category. However, G40 itself is not a billable code. You must use a more specific 6-character code, such as G40.909 (Epilepsy, unspecified, not intractable, without status epilepticus), to indicate the type, intractability, and presence of status epilepticus. 

Is G40 a billable code?

No, G40 is a non-billable category header. In 2026, CMS requires the highest level of specificity. You must select a sub-code (e.g., G40.301 or G40.911) that includes digits for intractability and status epilepticus to avoid claim denials. 

What is the ICD 10 code for intractable epilepsy?

Intractable epilepsy is coded using the G40 sub-series with a '1' in the 5th or 6th position. For example, G40.919 represents "Epilepsy, unspecified, intractable, without status epilepticus." Documentation must support that the condition is treatment-resistant or refractory. 

Can epilepsy be coded and billed through telehealth in 2026?

Yes. Under the 2026 CMS Physician Fee Schedule, neurology visits for epilepsy management remain eligible for telehealth reimbursement. However, the documentation must explicitly state the technology used (audio-visual vs. audio-only) and why telehealth was appropriate for the seizure history review. 

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