This document amends title 19 of the Code of Federal Regulations by prescribing an alternative procedure by which payers of the quarterly harbor maintenance fee (HMF) may submit payments or refund requests to Customs and Border Protection (CBP) electronically via an Internet account established by the payer and located at http://www.pay.gov. CBP will continue to accept quarterly HMF payments or refund requests via mail. These changes are intended to provide the trade with expanded electronic payment/refund options and to modernize and enhance CBP's port use fee collection efforts. This document also clarifies the regulations to reflect that both HMF supplemental payments and refund requests must be accompanied by the requisite CBP Form 350 (HMF Amended Quarterly Summary Report) and CBP Form 349 (HMF Quarterly Summary Report). This clarification is necessary to remove any ambiguity as to what forms are required in conjunction with such payments.