Harbor Maintenance Fee (HMF)

The Harbor Maintenance Fee is a CBP user fee that funds the maintenance and dredging of U.S. ports, charged only on ocean and other waterborne cargo. The rate is 0.125% of the cargo's customs value, with no minimum and no cap — unlike MPF, it scales without limit on large shipments. Crucially, it does not apply to air freight, so a $500,000 electronics shipment flown in pays $0 HMF while the same shipment arriving by sea owes $625. Like MPF, it is a fee rather than a tariff and is not waived by free-trade agreements, so importers must budget it separately (roughly 0.47% of CIF value in combined MPF + HMF on ocean shipments) when comparing sea versus air.