Is ICD-10-CM code E66 billable?

No, E66 (Overweight and obesity) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code E66 belong to?

E66 belongs to Chapter 4 of the ICD-10-CM tabular list: E00–E89 (Endocrine, Nutritional and Metabolic Diseases).

E66Not billable, use a more specific code below

Overweight and obesity

In Overweight, obesity and other hyperalimentation (E65-E68), chapter 4: Endocrine, Nutritional and Metabolic Diseases

10 billable codes under E66: 1 is a CC; 3 map to HCC 48 (Morbid Obesity).A CC or MCC (major CC) is a secondary diagnosis that raises the MS-DRG payment. An HCC counts toward a Medicare Advantage patient's risk score.

Instructional notes

Excludes2: not included here, code separately if applicable

adiposogenital dystrophy (E23.6)
lipomatosis dolorosa [Dercum] (E88.2)
lipomatosis NOS (E88.2)
Prader-Willi syndrome (Q87.11)

Code first: code the underlying condition first, then this code

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

Use additional code: add a second code for this, listed after this one

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

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Section I.C.4.b Obesity (page 42), covers E66
Category E66 has codes for causes and effects of obesity. Obesity class codes (E66.81-) need provider documentation and may be reported with other obesity codes, but code only class 3 when morbid obesity is also documented.

All codes under E66

E66 can't be used on a claim. Pick a billable code below; grey headings group them.

E66 MS-DRGs

As the principal diagnosis, the billable codes under E66 group to MS-DRG 640, 641, 205, or 206 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

DRG 640 Miscellaneous Disorders of Nutrition, Metabolism, Fluids and Electrolytes with MCC (9 of 10 codes)
DRG 641 Miscellaneous Disorders of Nutrition, Metabolism, Fluids and Electrolytes without MCC (9 of 10 codes)
DRG 205 Other Respiratory System Diagnoses with MCC (1 of 10 codes)
DRG 206 Other Respiratory System Diagnoses without MCC (1 of 10 codes)

Other codes that refer to E66

Notes on these codes point to E66.

E88.81 Use Additional Code: obesity (E66.-)
O99.21 Use Additional Code: code to identify the type of obesity (E66.-)
R63.5 Excludes1: obesity (E66.-)
Z99.3 Code First: obesity (E66.-)

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Body Weight

Body weight is the total mass of your body. Keeping track of your weight is one way to check for changes in your health, but it can't tell you the whole story. That's because your weight includes muscle, bone, fat, and water. Also, everyday factors can play a role in your weight, such as your:

Obesity

Obesity is a disease that means having too much body fat. It is different from being overweight, which means weighing too much. Both terms mean that your weight is greater than what's considered healthy for your height.

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.