K21 — Gastro-esophageal reflux disease
K21 is a non-billable header ICD-10-CM code for gastro-esophageal reflux disease. It cannot be billed on its own: choose one of the more specific child codes below.
Excludes1 — never code together
These conditions cannot occur together. Billing both on the same encounter is a denial.
- newborn esophageal reflux (P78.83)
Other codes that can never be billed with K21
These codes carry an Excludes1 note pointing at K21. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading K21 alone.
- K20Esophagitis
Risk adjustment
K21 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
The condition this code belongs to
Every code for the condition on one page, which one applies when, and the mistake coders make with it.
Code history
K21 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Code to one of these instead K21
2 child codes. Green means billable.
Questions about K21
- Is K21 a billable ICD-10-CM code?
- No. K21 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
- Where does K21 sit in the tabular list?
- Diseases of the digestive system (K00-K95), in the block Diseases of esophagus, stomach and duodenum (K20-K31).
- What cannot be coded together with K21?
- K21 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter.