Q21 — Congenital malformations of cardiac septa

Not billable

Is Q21 billable?

No — Q21 is a non-billable header code. Q21 groups more specific codes and cannot be submitted on a claim. A valid ICD-10-CM code must be reported at the highest level of specificity available in its branch. Select one of the 17 billable codes beneath Q21.

Billable codes under this header

Q21 at a glance

Code	Q21
Description	Congenital malformations of cardiac septa
Billable	No — header code
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

Excludes1 — never code together

The conditions below can never be reported together with Q21 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.

acquired cardiac septal defect (I51.0)

Excludes2 — not included here — inherited from Chapter 17

The conditions below are not part of Q21, but a patient may have both at the same time. When documentation supports it, Q21 and the excluded code may both be reported.

inborn errors of metabolism (E70-E88)

What codes fall under Q21? (7)

How long has Q21 existed?

Q21 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.

Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.

Which codes are confused with Q21?

ICD-10-CM declares these codes mutually exclusive with Q21 — exactly one of each pair can be correct for a given encounter.

vs I51.0Cardiac septal defect, acquired