N519 remark code

Remittance advice remark code N519. Remark codes add detail to the reason code on the same claim line.

Invalid modifier combination

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What N519 means

Two or more modifiers on the line cannot be used together, so the payer rejected the combination.

Some modifiers contradict each other, such as one meaning professional component only and another meaning technical component only. N519 means the set of modifiers on the line did not make sense together.

It adds detail to a modifier related reason code, usually 4, and is corrected by fixing the modifiers, not by appeal.

Common causes

• Modifiers that describe opposite situations were placed on the same line.
• A pricing modifier and an informational modifier were put in the wrong order.
• A modifier was carried over from a template that did not apply to this service.

What to do next

1. Review each modifier on the line and what it means.
2. Remove or replace the modifier that conflicts with the service performed.
3. Put payment-affecting modifiers first if the payer requires that order.
4. Submit a corrected claim with the fixed modifiers.

Related codes

• N823 (remark code) Procedure modifier invalid or incomplete
• N822 (remark code) Procedure modifier missing
• 4 (reason code) Procedure code and modifier do not match