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Clinical Coding

Excludes1 vs Excludes2 in ICD-10-CM: Notes Explained

by Editorial Team

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Two of the smallest words in ICD-10-CM cause more denied claims and failed audits than almost any other convention: Excludes1 and Excludes2. They look nearly identical, they sit side by side in the Tabular List, and they are separated by a single digit — yet they mean opposite things. One forbids you from ever reporting two codes together; the other explicitly allows it. Getting them backwards produces the two classic failure modes of diagnosis coding: unbundling conditions that should never coexist, or dropping a legitimate secondary diagnosis that a payer expected to see. This guide explains both notes exactly as the ICD-10-CM Official Guidelines for Coding and Reporting (Section I.A) define them, walks through the other instructional notes that share the page, and gives worked examples with real, valid codes you can verify in our ICD-10 code browser.

Where Instructional Notes Live

Before comparing the two Excludes notes, it helps to know where the classification places instructions. ICD-10-CM is not a flat list; it is a hierarchy of chapters, blocks (sections), categories (three characters), subcategories, and finally billable codes. Instructional notes can attach at any of those levels, and a note attached higher up applies to everything beneath it.

That inheritance matters. An Excludes1 note printed at the three-character category level governs every code in that category, not just the line it sits next to. When you look up a specific code, you must read upward through its parent category and block to catch every note that applies. A good lookup tool surfaces the inherited notes on the child code so you do not have to reconstruct the hierarchy by hand; if you rely on a printed excerpt, always trace the code back to its category header. For more on that structure, see our guide to ICD-10-CM code structure and how the chapters are organized.

Includes and Inclusion Terms

An Includes note appears immediately under a chapter, block, or category and further defines, or gives examples of, the content of that heading. It answers the question "what belongs here?" Inclusion terms are the list of conditions printed beneath a code — alternative names and specific variants that the code is intended to capture. Neither note restricts anything; they confirm that your documented diagnosis maps to the code you are considering. If the phrase in the medical record matches an inclusion term, you are almost certainly in the right place.

Excludes1 — "NOT CODED HERE"

An Excludes1 note means "NOT CODED HERE." The excluded code and the code the note sits under are mutually exclusive — the two conditions cannot occur together, so the two codes must never be reported for the same patient at the same time. Excludes1 is used when the two forms of a condition are variants that cannot logically coexist: a congenital versus an acquired form, a Type 1 versus a Type 2 form, an "unspecified" line versus a fully specified one.

Worked example. A patient is documented with Type 2 diabetes mellitus without complications, E11.9. The category E11 carries an Excludes1 note for E10.-, type 1 diabetes mellitus. That means you can never report E11.9 together with E10.9 (Type 1 diabetes mellitus without complications) for the same encounter — a person is not simultaneously classified as both Type 1 and Type 2. If a claim carried both codes, an auditor would flag it immediately, because the Excludes1 relationship declares them impossible to hold at once. When you hit an Excludes1 note pointing at a code you were also about to assign, stop: your documentation review has surfaced a conflict, and only one of the two codes can be correct for that condition.

The Excludes1 Exception: Unrelated Conditions

There is one carefully defined exception, spelled out in the Official Guidelines, and it is the detail that separates a confident coder from a nervous one. When the two conditions named in an Excludes1 note are actually unrelated to each other, you may report both codes. The guidelines give this exact illustration: code F45.8, "Other somatoform disorders," carries an Excludes1 note for "sleep related teeth grinding" (G47.63), because teeth grinding is itself an inclusion term under F45.8. For a patient whose teeth grinding is a somatoform symptom, you assign only one code. But if a patient has a somatoform disorder and, separately, sleep related bruxism as an unrelated condition, it is permissible to assign both F45.8 and G47.63. The Excludes1 note blocks double-coding of one condition under two headings; it does not block coding two genuinely different conditions that happen to share the note. When you invoke this exception, the clinical documentation must clearly support that the conditions are distinct.

Excludes2 — "NOT INCLUDED HERE"

An Excludes2 note means "NOT INCLUDED HERE." It tells you the excluded condition is not part of the code the note sits under, but — and this is the crucial difference — a patient may have both conditions at the same time. When the record documents both, you are permitted, and often expected, to report both codes. Excludes2 is not a warning of a conflict; it is a signpost that says "this related condition lives elsewhere, and if the patient also has it, code it separately."

Worked example. Under J01, acute sinusitis, the Tabular List carries an Excludes2 note for chronic sinusitis (J32.-). Acute and chronic sinusitis are distinct conditions that can genuinely coexist — the classic "acute exacerbation of chronic sinusitis." So for a patient with an acute flare of a chronic maxillary sinus condition, you may report both J01.00 (acute maxillary sinusitis, unspecified) and J32.0 (chronic maxillary sinusitis), because the Excludes2 note confirms they are separate, additively codeable diagnoses. Note the contrast printed on the very same page: J01 also carries an Excludes1 note for "sinusitis NOS" (J32.9) — the unspecified line — because an unspecified sinusitis and an acute sinusitis cannot both describe the same single condition. Two notes, one heading, opposite instructions: that is exactly why the digit matters.

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Excludes1 vs Excludes2 at a Glance

  • Excludes1 = NOT CODED HERE = the conditions are mutually exclusive = never code both together (unless they are genuinely unrelated, the documented exception).
  • Excludes2 = NOT INCLUDED HERE = the excluded condition is separate = you may code both when the patient has both.

A memory aid that survives audits: Excludes1 means "pick one"; Excludes2 means "two are allowed." The mistake auditors see most often is treating an Excludes2 relationship as if it were Excludes1 and dropping a valid secondary diagnosis, which can understate a patient's severity and depress risk-adjusted reimbursement. The mirror mistake — reporting both codes across an Excludes1 boundary — produces edits and denials. Reading the digit correctly is worth real money and real compliance safety.

The Sequencing Notes: Code First, Use Additional Code, Code Also

The Excludes notes tell you whether two codes may coexist. A separate family of notes tells you, when two codes are needed, which order they go in. These govern the etiology/manifestation convention — the rule that an underlying cause is usually sequenced before the condition it produces.

  • Code first. Printed under a manifestation code, it instructs you to sequence the underlying condition first. For example, non-pressure chronic ulcer codes in category L97 carry a "Code first" instruction for any associated underlying condition, such as a diabetic ulcer, so the systemic disease leads and the ulcer follows.
  • Use additional code. Printed under the underlying/etiology code, it instructs you to add a secondary code for an associated condition. For example, category E11 (Type 2 diabetes) says to "use additional code" to identify long-term insulin use, Z79.4, when applicable. "Code first" and "Use additional code" are two ends of the same paired-coding relationship, viewed from opposite codes.
  • Code also. This note flags that two codes may be required to fully describe a condition, but it does not dictate sequencing. The order depends on the severity and the reason for the encounter, so the coder decides which is principal based on the documentation.

Unlike Excludes1, none of these three notes ever prohibits a combination — they assume two codes and manage their relationship. Reading them together with the Excludes notes gives you the full instruction set for any given code.

A Practical Reading Workflow

When you land on a candidate code, read its notes top-down before you commit:

  • Confirm the documented diagnosis against the Includes note and inclusion terms.
  • Check every Excludes1 note on the code and its parent category. If one names another code you also intend to assign, resolve the conflict — pick one, unless the unrelated-conditions exception genuinely applies.
  • Check every Excludes2 note. If the patient also has the excluded condition, add that code too.
  • Apply any Code first / Use additional code / Code also instruction to sequence paired codes correctly.
  • Verify the final code is billable (a complete leaf, not a three-character header) for the date of service.

Because these notes are inherited down the hierarchy and updated every fiscal year, the fastest reliable way to see them all in one place is a lookup tool that renders the inherited notes on each result. Our ICD-10 code browser loads the full CMS dataset into your browser and shows the Excludes and sequencing notes on each code so you can apply this workflow in seconds. If you are new to the lookup process itself, start with our walkthrough on how to look up an ICD-10-CM code.

Why These Notes Are Not Optional

The Excludes conventions are part of the Official Guidelines, which are a HIPAA-adopted standard — they are binding, not advisory. Payers build automated claim edits directly on Excludes1 relationships, so an Excludes1 violation is often caught the moment a claim is submitted. Excludes2 errors are quieter but costlier over time: silently omitting an allowed secondary code can systematically understate patient complexity across an entire population, distorting quality metrics and risk-adjusted payment. In both directions, the remedy is the same discipline — read the note, read the digit, and let the clinical documentation decide whether one code or two is correct. ICD-10-CM is maintained in the United States by CDC/NCHS together with CMS, and both the classification files and the guidelines are refreshed every fiscal year. No lookup tool, including ours, replaces the Official Guidelines or a credentialed coder's judgment; use it to find and understand the notes fast, then verify every selection against the current guidelines before the code reaches a claim.

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