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F99 vs R45.851

F99 (Mental disorder, not otherwise specified) compared with R45.851 (Suicidal ideations), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes can be reported together when both conditions are documented, because R45.851 lists F99 under Excludes2, which marks them as distinct conditions.

Official rule
What is different?

The conditions named and chapter.F99 is “Mental disorder, not otherwise specified”; R45.851 is “Suicidal ideations”. F99 sits in F01-F99 — Mental, Behavioral and Neurodevelopmental Disorders (F01-F99); R45.851 in R00-R99 — Symptoms, Signs and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified (R00-R99).

Registry fact

Can these codes be reported together?

Yes, when both are documented.R45.851 lists F99 under Excludes2: “symptoms and signs constituting part of a pattern of mental disorder (F01-F99)”. Excludes2 marks distinct conditions that may both be reported when both are documented.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes2 relationship?

Yes.R45.851’s tabular entry: “symptoms and signs constituting part of a pattern of mental disorder (F01-F99)”. The note covers F99.

Official ruleGuide: Excludes1 vs Excludes2

Nothing found in 4 other checks; 1 check does not apply
Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. F99 carries 1 Excludes1 note and R45.851 carries 1 Excludes1 note covering other codes; the side-by-side table quotes them.

Official rule

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

No.Both are billable codes, and neither contains the other.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Excludes2 relationship

R45.851
Suicidal ideations
↔
F99
Mental disorder, not otherwise specified

What we found

Yes, when both are documented.R45.851 carries an Excludes2 note covering F99: “symptoms and signs constituting part of a pattern of mental disorder (F01-F99)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, 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, when appropriate.

    ICD-10-CM Official Guidelines FY2027

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
F99

Mental disorder, not otherwise specified

R45.851

Suicidal ideations

StatusSame for both
Billable
Excludes1Differs
F99
  • unspecified mental disorder due to known physiological condition (F09)
R45.851
  • suicide attempt (T14.91)
Excludes2Differs
F99

None at this code

R45.851
  • symptoms and signs constituting part of a pattern of mental disorder (F01-F99)
CategoryDiffers
F99

Is itself a category

R45.851

R45 Symptoms and signs involving emotional state

ChapterDiffers
F99

F01-F99 — Mental, Behavioral and Neurodevelopmental Disorders (F01-F99)

R45.851

R00-R99 — Symptoms, Signs and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified (R00-R99)

IncludesDiffers
F99
  • Mental illness NOS
R45.851

None at this code

No Code first, Use additional code, Code also and 7th character note at either code.

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on. In a row that differs, each code’s own notes are listed under it, and the notes every code shares are listed once beneath them.

Edit this comparisonCheck a whole claim

Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources