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 an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

K21

K21 — Gastro-esophageal reflux disease

Non-billable headerICD-10-CM

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.

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 an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.