ICD-10 Q21
Non-Billable HeaderCongenital malformations of cardiac septa
About ICD-10-CM Q21
ICD-10-CM code Q21 represents Congenital malformations of cardiac septa. This is a non-billable header code in the Congenital Malformations chapter (block Q21). The 2026 edition of ICD-10-CM Q21 became effective on October 1, 2025. Non-billable codes cannot be used as a primary or secondary diagnosis on a claim, use a more specific child code instead.
Type 1 Excludes
Pure excludes, these codes can never be coded together with Q21. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- acquired cardiac septal defect (I51.0)
Medicare LCD Coverage for Q21
Local Coverage Determinations (LCDs) from CMS MACs that list Q21 as a covered diagnosis.
This doesn't mean the code isn't covered, it means no MAC has issued a Local Coverage Determination naming this specific code. Coverage may still apply under National Coverage Determinations or general medical-necessity rules.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing Q21.
Our payer policy database covers Aetna, Cigna, Anthem, BCBS, Humana, and Medicare Advantage plans, but Q21 doesn't currently appear in any indexed policy. The code may still be covered under standard plan benefits.
CPT Codes Commonly Billed with Q21
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Codes Adjacent To Q21
Other codes in section Q20-Q28 (Congenital malformations of the circulatory system).
ICD-10 Q21, Billing FAQ
Is ICD-10 code Q21 billable? +
No, Q21 is a non-billable header code. Use a more specific child code from block Q21 when submitting claims.
What codes are Type 1 Excludes for Q21? +
Type 1 Excludes (never code together with Q21): acquired cardiac septal defect (I51.0)
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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