Q21Header code — not billable
Congenital malformations of cardiac septa
- Chapter
- 17. Congenital malformations, deformations and chromosomal abnormalities
- Category
- Q21
- Effective date
- October 1, 2026
Related codes in category Q21
Q21.0Ventricular septal defectYesQ21.1Atrial septal defectQ21.10Atrial septal defect, unspecifiedYesQ21.11Secundum atrial septal defectYesQ21.12Patent foramen ovaleYesQ21.13Coronary sinus atrial septal defectYesQ21.14Superior sinus venosus atrial septal defectYesQ21.15Inferior sinus venosus atrial septal defectYesQ21.16Sinus venosus atrial septal defect, unspecifiedYesQ21.19Other specified atrial septal defectYesQ21.2Atrioventricular septal defectQ21.20Atrioventricular septal defect, unsp as to part or completeYes
Frequently asked questions
What is ICD-10 code Q21?
Q21 is an ICD-10-CM diagnosis code for Congenital malformations of cardiac septa.
Is Q21 a billable code?
No. Q21 is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is Q21 in?
Q21 falls under Chapter 17: Congenital malformations, deformations and chromosomal abnormalities.
When did Q21 become effective?
Q21 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to Q21?
Q21 belongs to category Q21, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.