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ICD-10-CM 2027 diagnosis code

E66.813Obesity, class 3

✓ Billable / specific

E66.813 is a valid, billable ICD-10-CM code for obesity, class 3. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2025 (effective October 1, 2024). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About E66.813

E66.813 is the ICD-10-CM diagnosis code for obesity, class 3. It belongs to category E66 (Overweight and obesity), block E65-E68 (Overweight, obesity and other hyperalimentation) and chapter 4 (endocrine, nutritional and metabolic diseases). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within E66.81 (obesity class), E66.813 is specifically for obesity, class 3. Related codes cover 1 (E66.811) and 2 (E66.812).

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

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

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 640 (Miscellaneous Disorders of Nutrition, Metabolism, Fluids and Electrolytes with MCC, relative weight 1.3395) and DRG 641 (Miscellaneous Disorders of Nutrition, Metabolism, Fluids and Electrolytes without MCC, relative weight 0.7865), in MDC 10 (Endocrine, Nutritional and Metabolic Diseases and Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It was added in FY2025, effective October 1, 2024.

Notes that apply from higher levels

Instructions written at a parent level also apply to E66.813.

› From E66 Overweight and obesity
Excludes2
  • adiposogenital dystrophy (E23.6)
  • lipomatosis dolorosa [Dercum] (E88.2)
  • lipomatosis NOS (E88.2)
  • Prader-Willi syndrome (Q87.11)
Code first
  • obesity complicating pregnancy, childbirth and the puerperium, if applicable (O99.21-)
Use additional code
  • code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-)

Broader instructions also apply from Chapter 4: Endocrine, nutritional and metabolic diseases.

Alphabetic index entries

1 entries

Terms in the official ICD-10-CM index that lead to E66.813.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2025 (effective 10/1/2024): Added
  • No changes since FY2025.

Common questions about E66.813

Is E66.813 billable?

Yes. E66.813 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can E66.813 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict E66.813 as a principal diagnosis.

Is E66.813 a CC or MCC?

No. E66.813 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does E66.813 group to?

E66.813 is used in the MS-DRG v44.0 logic for MS-DRG 640 (Miscellaneous Disorders of Nutrition, Metabolism, Fluids and Electrolytes with MCC) and MS-DRG 641 (Miscellaneous Disorders of Nutrition, Metabolism, Fluids and Electrolytes without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.