Is K05.21 a billable ICD-10-CM code?

No. K05.21 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does K05.21 sit in the tabular list?

Diseases of the digestive system (K00-K95), in the block Diseases of oral cavity and salivary glands (K00-K14).

What cannot be coded together with K05.21?

K05.21 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above K05.21 (K05.2) and apply to it just the same.

K05.21

K05.21 — Aggressive periodontitis, localized

Non-billable headerICD-10-CM

K05.21 is a non-billable header ICD-10-CM code for aggressive periodontitis, localized. It cannot be billed on its own: choose one of the more specific child codes below.

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

Periodontal abscess

Excludes1 inherited from the categories above K05.21

These are not written on K05.21, but they bind it: a note on a category applies to every code beneath it. Billing K05.21 with anything listed here is a denial.

Written on K05.2 — Aggressive periodontitis

acute apical periodontitis (K04.4)
periapical abscess (K04.7)
periapical abscess with sinus (K04.6)

Risk adjustment

K05.21 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 history

K05.21 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 K05.21

4 child codes. Green means billable.

Related codes at this level

Codes that share K05.2. If K05.21 is not quite right, the correct code is usually one of these.

Questions about K05.21

Is K05.21 a billable ICD-10-CM code?: No. K05.21 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does K05.21 sit in the tabular list?: Diseases of the digestive system (K00-K95), in the block Diseases of oral cavity and salivary glands (K00-K14).
What cannot be coded together with K05.21?: K05.21 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above K05.21 (K05.2) and apply to it just the same.