Excludes1 vs Excludes2: The Complete Guide for Medical Coders
One of the most commonly misunderstood aspects of ICD-10-CM coding is the difference between Excludes1 and Excludes2 notes. Getting this wrong can lead to claim denials, compliance issues, and revenue loss. This guide explains everything you need to know.
In This Article
1. What Are Excludes Notes?
In the ICD-10-CM Tabular List, many codes include special notes called Excludes1 and Excludes2. These notes tell medical coders about relationships between diagnosis codes and whether certain codes can or cannot be reported together on the same claim.
The Centers for Medicare and Medicaid Services (CMS) publishes these notes as part of the official ICD-10-CM guidelines. They are updated annually, with new codes and rules taking effect each October 1st at the start of the federal fiscal year.
2. Excludes1: Mutually Exclusive Codes
❌ Excludes1 = NEVER code together
An Excludes1 note means the two conditions cannot occur together. They are mutually exclusive. If an Excludes1 note appears under a code, you should NEVER report that code with the excluded code on the same claim.
Excludes1 means “NOT CODED HERE.” The condition represented by the excluded code should never be coded at the same time as the code it is excluded from.
Example: Code E11 (Type 2 diabetes mellitus) has an Excludes1 note for E10 (Type 1 diabetes mellitus). A patient cannot have both Type 1 and Type 2 diabetes simultaneously.
When you encounter an Excludes1 conflict, you must determine which condition is the correct diagnosis and report only that code.
3. Excludes2: Conditions Not Included Here
⚠️ Excludes2 = CAN code together if documented
An Excludes2 note means the excluded condition is not part of the current code, but a patient CAN have both conditions at the same time. If both are documented, you may report both codes.
Excludes2 means “NOT INCLUDED HERE.” Unlike Excludes1, both conditions CAN exist simultaneously in the same patient.
Example: Code J45 (Asthma) may have an Excludes2 note for J44 (Chronic obstructive pulmonary disease). A patient can have both asthma and COPD. If both conditions are documented, you may report both codes.
The key with Excludes2 is documentation. Both conditions must be clearly documented by the provider.
4. Key Differences at a Glance
| Feature | Excludes1 | Excludes2 |
|---|---|---|
| Meaning | Not coded here | Not included here |
| Can coexist? | No — mutually exclusive | Yes — if documented |
| Code together? | NEVER | Yes, if both exist |
| Claim impact | Denial likely | Accepted if documented |
| Severity | Error | Warning / Informational |
5. Real-World Examples
Excludes1 Example: Diabetes
E11.9 (Type 2 diabetes without complications) has an Excludes1 for E10.9 (Type 1 diabetes without complications).
❌ You cannot report E11.9 and E10.9 together.
Excludes2 Example: Hypertension
I10 (Essential hypertension) may have an Excludes2 for certain hypertensive conditions.
⚠️ Both codes CAN be reported if the patient has both conditions and both are clearly documented.
6. How to Check Excludes Conflicts
Manually checking Excludes notes for every code combination is time-consuming and error-prone.
🧪 Try the Free Excludes Checker
ICD10Check.com offers a free Excludes Checker that validates Excludes1 and Excludes2 conflicts instantly.
Open Excludes Checker →7. Common Mistakes to Avoid
Treating Excludes2 as Excludes1
Excludes2 allows both codes if documented. Unnecessarily dropping a code leads to undercoding.
Ignoring inherited rules
Excludes notes on parent categories apply to all child codes. Always check parent category notes.
Not checking before claim submission
Excludes conflicts are a leading cause of claim denials. Always validate before submitting.
Using outdated code references
ICD-10-CM codes change every October 1. Always use the current fiscal year data.
Summary
Excludes1 means never code together (mutually exclusive), while Excludes2 means both codes can be reported if both conditions genuinely exist and are documented.
Use the ICD10Check Excludes Checker to validate your code combinations against the official CMS ICD-10-CM 2026 dataset.