HCPCS Level II code A4554 designates disposable underpads in all sizes, a common absorbent product used across clinical and long-term care settings to protect bedding and equipment from fluids. Nationally, this code matters because it standardizes billing for a frequently used supply in home health, skilled nursing, inpatient and outpatient care, and hospice services, influencing supply management and reimbursement workflows. Key payers referenced include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. This publication provides a concise overview of the code’s clinical role and billing context, and outlines what readers will find: national benchmarking context where available, common payer coverage considerations, typical service lines and sites of service, and operational notes relevant to billing teams. Readers will learn how A4554 is typically used in care delivery, which settings commonly bill the code, and what gaps exist in available input data. Data not available in the input is clearly indicated where applicable.