HCPCS Level II code S9992 covers transportation costs for clinical trial participants and one caregiver or companion, including fares for taxicab, bus, and local transit to and from trial locations. This code matters nationally as it facilitates participant access to clinical research by capturing nonmedical transportation expenses that can be a barrier to trial enrollment and retention. Recognizing and billing for these costs supports study participation equity and operational billing transparency.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of what S9992 represents, the typical service setting, and which major payers commonly address these charges. The publication outlines benchmarks and billing context where available, summarizes relevant policy considerations affecting coverage of clinical trial transportation, and highlights operational implications for sites and sponsors seeking reimbursement for participant travel. The analysis is national in scope and focuses on how S9992 is used to document transportation support for clinical research participants and an accompanying caregiver.