Harbor Maintenance Fees (HMF) are U.S. government charges collected on certain waterborne cargo movements to help fund maintenance of commercial ports and harbors. In practice, the fee is assessed on qualifying imports that use harbor facilities, and it is usually handled as part of the overall ocean freight and customs billing process.
The fee is not a carrier’s optional surcharge; it is tied to the shipment’s use of ports covered by the program and is generally calculated from the declared value of the cargo when applicable. Who pays it depends on the transaction structure, but importers often see it itemized on customs or freight invoices rather than paying it directly at the dock.
For shippers, the important point is that HMF can affect landed cost even when the ocean freight rate looks straightforward. It is separate from customs duty, merchandise processing fees, terminal charges, and other port-related costs, so the total import expense may be higher than the transport quote alone suggests.