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E66 ICD-10-CM Code: Overweight and obesity

Compare with another code for E66Check this code on a claim

Billing Status: NO. This is a non-billable ICD-10-CM code: report a more specific billable code beneath it.

Coding at a Glance

Official instructions
4 Excludes2 · 1 use-additional instruction · 1 code-first instruction

What these terms mean →

Category · FY2027A non-billable heading in the tabular list: report a more specific code beneath it.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

Code firstSequence the underlying condition before this code
  • obesity complicating pregnancy, childbirth and the puerperium, if applicable (O99.21-)
Use additional codeReport with this code when documented
  • Use additional code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-)
Excludes2Not included here; may be reported together
  • adiposogenital dystrophy (E23.6)
  • lipomatosis dolorosa Dercum
  • lipomatosis NOS (E88.2)
  • Prader-Willi syndrome (Q87.11)

Where it sits Source: CMS/NCHS

Under:Chapter 4: Endocrine, Nutritional and Metabolic DiseasesE65-E68 Overweight, obesity and other hyperalimentation

Codes under E66 (6)

  • E66.0Obesity due to excess caloriesNot billable
  • E66.1Drug-induced obesityBillable
  • E66.2Morbid (severe) obesity with alveolar hypoventilationBillable
  • E66.3OverweightBillable
  • E66.8Other obesityNot billable
  • E66.9Obesity, unspecifiedBillable

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for E66 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Code First

Underlying conditions that must be sequenced before this code.

  • obesity complicating pregnancy, childbirth and the puerperium, if applicable (O99.21-)

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-)

Coder workflow for E66

MedCoder structured workflow — derived from this code’s own official record

Before you code E66

  1. E66 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewE66.0, E66.1, E66.2, E66.3, E66.8, E66.9

    See the relationships section · Guide: How to choose an ICD-10-CM code →

Choose the right path

  1. Does the documentation support one of the more specific codes beneath E66?
    Yes → Select that code and continue the checks below on its own page.
    No → E66 cannot be reported as written. Where the codes beneath it include an unspecified code, that code applies when the record goes no further; otherwise query for the missing detail.

    ReviewE66.0, E66.1, E66.2, E66.3, E66.8, E66.9

  2. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then the code beneath E66.
    No → Continue; do not add an underlying condition the record does not document.

    ReviewO99.21

Report the code beneath E66 that the documentation supports, not E66 itself. Then work the Use Additional Code note, and confirm that code is valid for the date of service on its own page.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The underlying (etiologic) condition
Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

  • Excludes2 — not part of E66(4 notes)

    Coding workflow: The conditions named in this note are not included in E66. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareE23.6, E88.2, Q87.11

    See the official tabular notes · Guidelines I.A.12.b

  • Code First — sequencing check(1 note)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before E66. Do not add an underlying condition the record does not document.

    ReviewO99.21

    See the official tabular notes · Guidelines I.A.13

  • Use Additional Code — after identifying E66(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with E66 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewZ68.5

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The underlying condition the Code First note names is documented alongside this condition.

Coding question: How are the two sequenced?

Path: Review the Code First note.

Reason: The underlying condition is sequenced first and the manifestation follows (Guidelines I.A.13).

ReviewO99.21

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with the code beneath E66?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewZ68.5

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse E66 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of E66 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • E23.6— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of adiposogenital dystrophy adds E23.6; it is not part of this code and both may be reported when both are documented.

    Full comparison: E66 vs E23.6 →

  • E88.2— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of lipomatosis NOS adds E88.2; it is not part of this code and both may be reported when both are documented.

    Full comparison: E66 vs E88.2 →

  • Q87.11— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of Prader-Willi syndrome adds Q87.11; it is not part of this code and both may be reported when both are documented.

    Full comparison: E66 vs Q87.11 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Overweight and obesity is a non-billable ICD-10-CM category code (E66). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Chapter 4: Endocrine, Nutritional, and Metabolic Diseases (E00 -E89)

b. Obesity The obesity codes in category E66, Overweight and obesity, include codes related to the cause of obesity, such as drug-induced obesity (E66.1), and codes related to effects of obesity, such as code E66.2, Morbid (severe) obesity with alveolar hypoventilation. There are other codes related to obesity in other categories of the classification, such as E88.82, Obesity due to disruption of MC4R pathway; and codes in fifth character subcategory O99.21, Obesity complicating pregnancy, childbirth, and the puerperium.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

  1. Sequencing: 1 Code First instruction — the underlying condition is sequenced before this code when present. See the Code First notes
  2. 1 Use Additional Code instruction — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  3. 4 Excludes2 entries — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name E66 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: R63.5 — Abnormal weight gain.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Code First instruction: Z99.3 — Dependence on wheelchair.

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 2 Use Additional Code instructions across 2 chapters: E88.81 — Metabolic syndrome and other insulin resistance, O99.21 — Obesity complicating pregnancy, childbirth, and the puerperium.

These codes instruct coders to additionally report this code when it applies.

Contextual Map

Every relationship of E66 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run E66 with these 9 related codes in Claim Check

Hierarchy

Excludes2

Code First

Use Additional Code

  • Z68 — Body mass index [BMI][Use Additional Code]: “code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027
  • Z68.5 — Body mass index [BMI] pediatric[Use Additional Code]: “code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027

Referenced by Excludes1 notes

Referenced by Code First instructions

Referenced by Use Additional Code instructions

Nearest codes (13)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Can E66 be billed directly?

No. E66 (Overweight and obesity) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2027), quoted by section Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

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

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "E66 — Overweight and obesity." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/e66-overweight-and-obesity

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Overweight and obesity

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to E66 in its code family, with their registry titles.