E66.81

Obesity class

FY2027Chapter 4: Endocrine, nutritional and metabolic diseases/E65–E68 Overweight, obesity and other hyperalimentation

Non-billable headerNot valid on its own. Use one of the more specific codes under it.

E66.81 is a non-billable ICD-10-CM code header for obesity class. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are E66.811 Obesity, class 1; E66.812 Obesity, class 2 and E66.813 Obesity, class 3. Its coding notes include a Code first instruction, a Use additional code instruction, 1 Excludes1 entry and 4 Excludes2 entries.

Guidelines tip

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

Obesity class codes depend on the provider documenting the class. If class 3 and morbid obesity are both documented, only class 3 is assigned.

Guidelines I.C.4.b.1Obesity class codesRead the official text

Code first

If the underlying condition listed here is present and known, sequence it first.

Inherited from E66 Overweight and obesity
  • obesity complicating pregnancy, childbirth and the puerperium, if applicable (O99.21-)

Use additional code

Add the listed code as a secondary code, if known.

Inherited from E66 Overweight and obesity
  • code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Also from chapter/block level (1 note)
Inherited from Chapter 4 Endocrine, nutritional and metabolic diseases
  • transitory endocrine and metabolic disorders specific to newborn (P70-P74)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Inherited from E66 Overweight and obesity
  • adiposogenital dystrophy (E23.6)
  • lipomatosis dolorosa [Dercum] (E88.2)
  • lipomatosis NOS (E88.2)
  • Prader-Willi syndrome (Q87.11)

Notes

Also from chapter/block level (1 note)
Inherited from Chapter 4 Endocrine, nutritional and metabolic diseases
  • All neoplasms, whether functionally active or not, are classified in Chapter 2. Appropriate codes in this chapter (i.e. E05.8, E07.0, E16-E31, E34.-) may be used as additional codes to indicate either functional activity by neoplasms and ectopic endocrine tissue or hyperfunction and hypofunction of endocrine glands associated with neoplasms and other conditions classified elsewhere.

More specific codes under E66.81 3