HCPCS Level II code G0400 denotes a home sleep test (HST) performed with a Type IV portable monitor that records a minimum of three channels, delivered in the patient’s home. This code matters nationally as home-based sleep testing is a widely used alternative to in-lab polysomnography for screening and diagnosing obstructive sleep apnea and other sleep-disordered breathing, offering lower cost and greater convenience while expanding access to diagnostic services.

Key payers covered in this overview include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise briefing on clinical context, typical sites of service, and the role of Type IV unattended monitoring. The publication summarizes payer coverage considerations, common billing modifiers, and where G0400 fits within diagnostic service lines. It also outlines what to expect in benchmarks and policy updates relevant to home sleep testing, and provides practical coding context for revenue cycle and compliance teams.

This summary is national in scope and intended to orient clinicians, billing professionals, and policy analysts to the clinical purpose and billing identity of G0400, and to point toward the detailed sections covering payer-specific rules, benchmarks, and documentation elements.