Excludes1 vs Excludes2

What is the difference between an Excludes1 and an Excludes2 note?

Applies to ICD-10-CM FY2027 · October 1, 2026 – September 30, 2027

The short answer

An Excludes1 note means the two conditions cannot occur together, so the two codes must never be reported on the same claim. An Excludes2 note means the excluded condition is separate but a patient may have both, so both codes may be reported together when the documentation supports it.

These two notes look almost identical on the page and mean close to opposite things. In ICD-10-CM FY2027 there are 3,091 codes carrying an Excludes1 note and 1,229 carrying an Excludes2, and confusing one for the other produces either a rejected claim or an under-coded record.

Excludes1 — “not coded here”

Official definition — Excludes1

A type 1 Excludes note is a pure excludes. It means 'NOT CODED HERE!' An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.

— ICD-10-CM Tabular List of Diseases and Injuries, FY2027, published by CDC/NCHS

Read Excludes1 as these two things are mutually exclusive. The classic case is a congenital form of a condition versus an acquired form: a patient has one or the other, not both, so the classification refuses to let you report both.

Excludes1 in practice

D69.1 (Qualitative platelet defects) carries an Excludes1 note for hemolytic-uremic syndrome (D59.3). Those are different mechanisms and the classification treats them as incompatible, so reporting both on one claim is a coding error regardless of what the record says.

Excludes2 — “not included here”

Official definition — Excludes2

A type 2 excludes note represents 'Not included here'. An excludes2 note indicates that the condition excluded is not part of the condition it is excluded from but a patient may have both conditions at the same time. When an Excludes2 note appears under a code it is acceptable to use both the code and the excluded code together.

— ICD-10-CM Tabular List of Diseases and Injuries, FY2027, published by CDC/NCHS

Read Excludes2 as this is a different thing, and it is fine to have both. The note exists to tell you that the condition is classified elsewhere, not to forbid the combination. If the record documents both conditions, report both codes.

Excludes2 in practice

D69.1 also carries an Excludes2 for von Willebrand disease (D68.0). Because it is an Excludes2 rather than an Excludes1, a patient documented with both a qualitative platelet defect and von Willebrand disease can have both codes reported.

The exception worth knowing

Excludes1 is not always absolute

CMS issued guidance that where two conditions covered by an Excludes1 note are genuinely unrelated to each other, both may be reported. If the record clearly supports two unrelated conditions that happen to sit either side of an Excludes1, query the provider and document the reasoning rather than assuming the note is unconditional.

This is the single most common source of argument about Excludes1. Treat the note as a hard stop by default, and treat the unrelated-conditions exception as something you document, not something you assume.

How to tell which one you are looking at

Excludes1 — ask “could one patient have both of these at once?” If the classification says no, this is why.
Excludes2 — the excluded condition is a genuinely separate problem that simply lives under a different code.
Both are inherited. A note declared on a three-character category applies to every code beneath it, even though the note is not reprinted there. On this site every code page shows inherited notes and names the ancestor that declared them.

Where the notes actually bite

An Excludes1 declared high in the hierarchy is easy to miss because it never appears on the code you are looking at. E11.9 has no Excludes1 of its own worth worrying about, but it inherits eight of them from E11 — including type 1 diabetes and gestational diabetes.

Both note types, with their source, are shown on every code page. See E11.9 for a worked example, or read how inheritance is resolved in the editorial policy.