Importing into the US means three separate charges on top of your product’s value: duty (set by your HTS code), the Merchandise Processing Fee, and, for ocean shipments, the Harbor Maintenance Fee. None of them are optional, and MPF catches a lot of first-time importers off guard because it has both a minimum and a maximum.
Where your duty rate comes from
Duty rate depends entirely on the 10-digit HTS (Harmonized Tariff Schedule) code for your specific product, not on a flat “import tax.” Two similar-looking products can have very different rates. Look your product up at hts.usitc.gov before you file, or ask your customs broker to classify it — misclassifying a product is one of the most common causes of a CBP audit.
MPF and HMF explained
MPF (Merchandise Processing Fee) applies to every formal entry regardless of mode. It’s 0.3464% of the customs value, but it’s capped at both ends: CBP sets a minimum and a maximum per entry, adjusted periodically for inflation. A $5,000 shipment and a $50,000 shipment can pay a very different effective MPF rate once the cap kicks in.
HMF (Harbor Maintenance Fee) is 0.125% of value, ocean shipments only, no cap. Air and truck entries don’t pay it.
Both fees are small on an individual shipment but add up fast for importers running frequent, lower-value entries — which is exactly the profile a lot of Amazon FBA and e-commerce importers have.
Duty vs Section 301
This calculator covers the normal (MFN) duty rate from your HTS code. If your goods originate in China, check whether an additional Section 301 tariff applies on top — those are separate, often much larger, and depend on the specific HTS line. Use the Section 301 tariff calculator for that stacked calculation.
Rates and fee caps are set by CBP and change periodically. Treat the figures here as a planning estimate and confirm exact numbers with your customs broker before filing an entry.