Two notes appear throughout ICD-10-CM that look almost identical and mean close to opposite things. Getting them backwards is one of the most reliable ways to have a claim rejected.
Excludes1: never code both
An Excludes1 note means “not coded here.” The two conditions are mutually exclusive - they cannot both be present in the way the classification describes them, so the two codes must never appear together on the same claim for the same encounter.
The usual reason is that one code already includes the other, or the two represent different forms of the same condition. A congenital form and an acquired form of the same problem are a classic Excludes1 pair: a patient has one or the other, not both.
Excludes2: not included here, but code both if present
An Excludes2 note means “not included here.” The excluded condition is not part of the code you are looking at, but a patient may genuinely have both at the same time. If the record documents both, code both.
This is the one people get wrong. An Excludes2 note is not a prohibition. It is telling you the code in front of you does not cover the other condition, so if that condition is also documented, it needs its own code.
Side by side
| Note | Meaning | Can both be coded? |
|---|---|---|
| Excludes1 | Not coded here - mutually exclusive | No, never together |
| Excludes2 | Not included here - separate condition | Yes, if both documented |
The exception to Excludes1
There is one important qualification, added after the rule caused problems in practice. If the two conditions joined by an Excludes1 note are genuinely unrelated to each other, both may be reported.
The guidance exists because some Excludes1 pairs were drafted assuming the conditions were always related, when in fact a patient can have both independently. If the documentation supports two unrelated conditions that happen to sit either side of an Excludes1 note, code both. If you are unsure whether they are related, that is a question for the provider, not a guess.
How to check before you submit
Every code page on this site lists the Excludes1 and Excludes2 notes that apply, clearly labelled, along with the includes and inclusion terms. Notes are also inherited down the hierarchy: a note at the chapter, section or category level applies to every code beneath it, which is why it is worth opening the category page as well as the code itself.
The practical habit is simple. Before submitting two diagnosis codes together, open both and read each one's excludes notes. It takes seconds and catches the pairing that would otherwise come back as a rejection.
Where to look next
Browse ICD-10-CM by chapter to see how notes cascade from chapter to section to category, or read about code first and use additional code, the other pair of instructional notes that governs how codes are combined.