ICD-10-CM 2027 diagnosis code

K21Gastro-esophageal reflux disease

Not billable — use a more specific code

K21 is a header code, so it can't be reported by itself. Choose one of the 2 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About K21

K21 is the ICD-10-CM diagnosis code for Gastro-esophageal reflux disease. It belongs to block K20-K31 (diseases of esophagus, stomach and duodenum) and chapter 11 (diseases of the digestive system). It is a header code, so it can't be reported by itself; one of its 2 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: K21.0 (with esophagitis) and K21.9 (without esophagitis).

Don't report K21 together with the conditions in its Excludes1 note: newborn esophageal reflux (P78.83).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under K21

Coding notes

Excludes1Not coded here — never report together with this code

newborn esophageal reflux (P78.83)

Notes that apply from higher levels

Instructions written at a parent level also apply to K21.

Broader instructions also apply from K20-K31 Diseases of esophagus, stomach and duodenum and Chapter 11: Diseases of the digestive system.

Codes whose notes reference K21

R63.31Code also
R63.32Code also

Code history

2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about K21

Is K21 billable?: No. K21 is a header code. Report one of its more specific subcodes instead.