Customs requires that these fees are paid at the time the duty is paid. Merchandise Processing Fee (MPF) is added to all entries. For formal entries they are assessed at .21% of the value of your shipment. The minimum is $25.00 and it shall not exceed $485.00 per entry. For informal entries the fee is $2.00. The Harbor Maintenance Fee (HMF) is assessed on all shipments that use U.S. Harbors (ocean freight). The fee is currently .125% based on the value of your shipment.