Modifier 63- Procedure Performed on Infants Less Than 4 kg

Modifier 63 is used to identify procedures performed on infants weighing less than 4 kilograms when the patient's size significantly increases the complexity of the procedure

What is Modifier 63?

Modifier 63 identifies procedures performed on infants weighing less than 4 kilograms (approximately 8.8 pounds) when the patient's small size substantially increases the physician's work. The modifier recognizes the additional technical difficulty, specialized skill, and increased time often required when performing eligible procedures on very small infants. Modifier 63 should only be reported when permitted by the procedure code and supported by complete medical documentation.

When to Use Modifier 63

• The patient weighs less than 4 kilograms at the time of the procedure.

• The procedure is eligible for Modifier 63 reporting.

• The infant's size significantly increases procedural complexity.

• Documentation supports the patient's weight and the additional physician work.

Billing Example

A pediatric surgeon performs a complex surgical procedure on a premature infant weighing 3.2 kilograms. Due to the infant's small anatomy and increased technical difficulty, Modifier 63 is appended to the procedure code when payer guidelines allow its use.

Documentation Tips

• Record the infant's exact weight on the date of service.

• Describe how the patient's size increased procedural complexity.

• Include a detailed operative report.

• Verify the procedure is eligible for Modifier 63 before submitting the claim.

Common Denial Reasons

• Patient weight is not documented.

• The reported procedure is not eligible for Modifier 63.

• Documentation does not support increased procedural complexity.

• Modifier reported contrary to payer billing guidelines.

Related Modifiers

Modifier 22

Modifier 62

Modifier 66

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