USA import duty and customs guide (2026)
How US import duty is calculated, when Section 301 and 232 tariffs stack on the HTSUS rate, and the entered-value, merchandise-processing-fee and harbor-maintenance-fee arithmetic that decides your landed cost.
US import duty looks simple - one HTSUS rate times the invoice value - until you meet Section 301 China tariffs, Section 232 steel surcharges, the Merchandise Processing Fee and the Harbor Maintenance Fee stacking on the same entry. This guide walks through the exact 2026 arithmetic that a US customs broker files on CBP Form 7501.
The base formula
Duty = Entered value x HTSUS ad-valorem rate
Entered value is the transaction value in USD (FOB origin unless otherwise agreed), converted at the CBP quarterly rate in effect on the export date. The HTSUS rate comes from the eight-digit line for the good; the ten-digit statistical suffix does not change duty.
Section 301 and 232 surcharges
Section 301 tariffs apply to Chinese-origin goods on the USTR List 1 to List 4A schedules (7.5% to 25%). Section 232 tariffs apply to steel (25%) and aluminium (10% or 25% depending on melt-and-pour origin). Both are additive - a Chinese steel elbow can carry a 3.7% HTSUS base, a 25% Section 301 surcharge and a 25% Section 232 surcharge, so 53.7% total ad valorem.
MPF and HMF fees
The Merchandise Processing Fee is 0.3464% of entered value, floored at USD 32.71 and capped at USD 634.62 per entry (2026 values). Manual entries under USD 2,500 pay USD 3.33 flat. The Harbor Maintenance Fee is 0.125% of entered value on any ocean shipment discharged at a US port, uncapped. Air and truck entries pay MPF only.
De minimis and Section 321
Shipments at or below USD 800 per consignee per day enter under Section 321 as informal entries - no duty, no MPF, no HMF. Exceptions: goods subject to a Partner Government Agency hold (FDA, USDA), goods on the Section 232/301 exclusion pull-list, and, since 2025, most China-origin apparel and textiles.
Worked example
USD 25,000 shipment of Chinese-origin steel pipe fittings (HTSUS 7307.99.5060 - 4.3% base, 25% Section 301, 25% Section 232), ocean freight to Los Angeles:
- HTSUS duty: 25,000 x 4.3% = USD 1,075
- Section 301: 25,000 x 25% = USD 6,250
- Section 232: 25,000 x 25% = USD 6,250
- MPF: 25,000 x 0.3464% = USD 86.60
- HMF: 25,000 x 0.125% = USD 31.25
- Total US charges: USD 13,692.85 (54.8% of entered value)
Frequently asked questions
How is US import duty calculated?#
Duty = entered value x HTSUS ad-valorem rate. Entered value is the transaction value in USD (FOB origin, unless the parties agreed otherwise), converted at the CBP rate on the date of export. On top, you add the Merchandise Processing Fee (0.3464% of entered value, minimum USD 32.71 and maximum USD 634.62 in 2026) and, for ocean shipments, the Harbor Maintenance Fee (0.125% of entered value, no cap).
When do Section 301 and Section 232 tariffs apply?#
Section 301 tariffs are country-specific surcharges - most notably 7.5% to 25% on wide lists of goods from China - added on top of the HTSUS rate. Section 232 tariffs are product-specific national-security surcharges on steel (25%) and aluminium (10% or 25% depending on origin). Both stack: a Chinese-origin steel fitting can carry HTSUS + Section 301 + Section 232 in the same entry.
What is the USA de minimis threshold in 2026?#
USD 800 per person per day for informal entries under Section 321. Shipments at or below the threshold enter duty-free and MPF-free provided they are not subject to a Partner Government Agency hold or a Section 232/301 exclusion. The Biden-era rulemaking to exclude China-origin apparel from de minimis is now in effect; verify the current scope before promising duty-free entry.
How do I use HTSUS chapter and heading numbers?#
HTSUS is a ten-digit code: the first six digits align with the WCO Harmonized System (used worldwide), digits 7-8 are US-specific tariff distinctions, and digits 9-10 are statistical suffixes for trade data. The duty rate lives at the eight-digit level; brokers file at ten digits. The HS Code Lookup tool cross-walks a description to the eight-digit US line.
Which incoterm minimises US import duty?#
None - duty is a function of goods value and classification, not incoterm. What incoterm affects is who declares the value and pays. Under DDP the seller becomes the Importer of Record and pays; under FOB / CIF the buyer is IOR. FCA is popular for US inbound because it lets the buyer control the freight (and use their forwarder) while the seller still hands over at origin.