An Excludes1 note in ICD-10-CM means “NOT CODED HERE.” The code above the note and the excluded code are never reported together, because the two conditions cannot occur together or one is a form of the other. The one exception, in guideline I.A.12.a, is when the two conditions are unrelated to each other, in which case both may be coded.
Understanding ICD-10-CM Excludes 1 Notes
What Is an Excludes 1 Note?
In ICD-10-CM, an Excludes 1 note is a pure exclusion note. It means that you cannot report the two conditions together because they cannot occur at the same time or are mutually exclusive.
When you see an Excludes 1 note under a code, it tells you that if the condition listed in the Excludes 1 note is present, you must code that condition instead of the main code—you should not assign both codes for the same patient encounter.
Official ICD-10-CM Definition
An Excludes 1 note indicates that the code excluded should never be used at the same time as the code above the Excludes 1 note. It is used when two conditions cannot occur together.
In simple terms, Excludes 1 = “NOT coded here.”
Examples of Excludes 1 Notes
Example 1:
-
M54.50: Low back pain, unspecified
-
Excludes 1: M54.4-: Lumbago with sciatica (M54.40, M54.41, M54.42)
This means if the provider documents lumbago with sciatica, you cannot also assign low back pain (M54.50). Instead, you use only the correct M54.4- code, such as M54.41 for the right side. Note that M54.5 itself has not been a valid code since October 2021. The Excludes 1 note sits at the M54.5- level, so it applies to M54.50, M54.51, and M54.59.
-
Example 2:
-
F10.10 – Alcohol abuse, uncomplicated
-
Excludes 1: F10.20 – Alcohol dependence, uncomplicated
You cannot report both alcohol abuse and alcohol dependence together. Only one applies.
-
Why Excludes 1 Matters
-
Prevents double-counting: ensures that coders do not report diagnoses redundantly.
-
Improves data accuracy: aligns with clinical logic because it separates conditions that cannot coexist.
-
Affects reimbursement: incorrect dual coding can lead to claim denials or inaccurate risk adjustment.
-
Supports compliance: following Excludes 1 rules keeps coding aligned with ICD-10-CM Official Guidelines for Coding and Reporting.
Common Mistakes with Excludes 1
-
Ignoring updated guidelines: Some Excludes 1 notes changed over the years, so always use the latest code set.
-
Coding both diagnoses together: if documentation supports both, verify whether one note was reclassified to Excludes 2 in newer updates.
-
Not reviewing parent categories: Excludes 1 can appear at the category, subcategory, or code level—always read all hierarchy levels.
Coder Tips
-
Always review tabular list notes, not just the index.
-
When uncertain whether conditions can coexist, check the most recent ICD-10-CM guidelines or Coding Clinic references.
-
Use Excludes 1 as a reminder to query providers if documentation appears conflicting.
Key Takeaway
Excludes 1 = “Never code together.”
It signals that the two conditions are mutually exclusive, so you can report only one for that encounter. Careful attention to these notes ensures compliance, prevents errors, and strengthens coding accuracy.
Medical Coding ICD-10-CM Chapters
Frequently Asked Questions About Excludes1 Notes
What does Excludes1 mean in ICD-10-CM?
Excludes1 is a pure excludes note. It means the excluded code should never be used at the same time as the code above the note.
Is there ever an exception to an Excludes1 note?
Yes. Under ICD-10-CM guideline I.A.12.a, when the two conditions are unrelated to each other, it is acceptable to report both codes together. Code from the documentation and query the provider if the relationship is unclear.
What is the difference between Excludes1 and Excludes2?
Excludes1 means not coded here, so do not report both. Excludes2 means not included here: the excluded condition is not part of the code above it, but the patient can have both, so both may be reported when documented.
Where do Excludes1 notes appear?
They can appear at the chapter, category, subcategory or code level, and they apply to every code below that level. Always check the parent levels.
How are Excludes notes tested on the CPC exam?
Expect diagnosis scenarios where two codes look correct but an Excludes1 note rules one out. Reading the Tabular List for every code is the fastest way to catch them.