HCPCS Level II code J1558 denotes a 100 mg unit of immune globulin (Xembify) administered as an injectable biologic. This product is used in immune deficiency and certain immunomodulatory indications and is billed per 100 mg increment. Nationally, accurate coding for immune globulin products matters because it affects billing precision, inventory tracking, and payer coverage determination for high-cost biologic therapies.

Key payers included in this overview are Aetna, Blue Cross Blue Shield, Cigna, UnitedHealthcare, and Medicare. Readers will find an overview of what the code represents clinically and operationally, typical sites of service, and which payers are relevant for coverage and billing considerations. The publication also outlines benchmarks and policy context where available and highlights common billing themes for injectable biologics, including unitization and site-of-service implications.

This summary is intended for billing administrators, revenue cycle professionals, and clinicians involved in infusion and injection services. Data not available in the input will be noted where applicable in detailed sections.