Q21.1 – Atrial septal defect

ICD-10-CM 2027 diagnosis code · Congenital malformations of the circulatory system

Non-billable header

ICD-10-CM code Q21.1

Code: Q21.1 (claims format: Q211)
Description: Atrial septal defect
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 17. Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1)
Block: Q20-Q28 Congenital malformations of the circulatory system
Parent codes: Q21

Billable codes under Q21.1

Q21.1 is a header code and cannot be used on claims. Choose the most specific code:

Q21.10 – Atrial septal defect, unspecifiedBillable
Q21.11 – Secundum atrial septal defectBillable
Q21.12 – Patent foramen ovaleBillable
Q21.13 – Coronary sinus atrial septal defectBillable
Q21.14 – Superior sinus venosus atrial septal defectBillable
Q21.15 – Inferior sinus venosus atrial septal defectBillable
Q21.16 – Sinus venosus atrial septal defect, unspecifiedBillable
Q21.19 – Other specified atrial septal defectBillable

Notes for Q21.1

Excludes2 (not included here):

ostium primum atrial septal defect (type I) (Q21.20)

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Q21 – Congenital malformations of cardiac septa

Excludes1 (not coded here):

acquired cardiac septal defect (I51.0)

Related codes in Q21

Q21.0 – Ventricular septal defectBillable
Q21.2 – Atrioventricular septal defectHeader
Q21.3 – Tetralogy of FallotBillable
Q21.4 – Aortopulmonary septal defectBillable
Q21.8 – Other congenital malformations of cardiac septaBillable
Q21.9 – Congenital malformation of cardiac septum, unspecifiedBillable

Frequently asked questions

What is ICD-10 code Q21.1?

Q21.1 is the ICD-10-CM code for atrial septal defect, in the block Q20-Q28 (Congenital malformations of the circulatory system).

Is Q21.1 a billable code?

No. Q21.1 is a header code with more specific child codes; report one of the billable codes listed above.

What category does Q21.1 belong to?

It belongs to category Q21 – Congenital malformations of cardiac septa.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.