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 and aluminium and their listed derivatives at 50% since 4 June 2025 (UK-origin goods at 25%). Both are additive - a Chinese steel elbow can carry a 3.7% HTSUS base, a 25% Section 301 surcharge and a 50% Section 232 surcharge, so 78.7% total ad valorem. The 2025 reciprocal tariffs imposed under IEEPA no longer apply: the Supreme Court held on 20 February 2026 (Learning Resources v. Trump) that IEEPA does not authorise tariffs, and CBP stopped collecting them from 24 February 2026. Replacement surcharges (for example under Section 122 of the Trade Act of 1974) can be added by proclamation, so check the current Chapter 99 headings for the country of origin.
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
The Section 321 de minimis exemption used to let shipments at or below USD 800 per consignee per day enter free of duty and fees. Since 29 August 2025 that duty-free treatment is suspended for goods from all countries, so low-value commercial shipments now pay the applicable duties and need a formal or informal entry. Budget duty on every consignment, whatever its value, and check current CBP guidance for postal shipments.
Worked example
USD 25,000 shipment of Chinese-origin steel pipe fittings (HTSUS 7307.99.5060 - 4.3% base, 25% Section 301, 50% Section 232), ocean freight to Los Angeles. Illustrative only, not a ruling; any temporary country-wide surcharge is excluded:
- HTSUS duty: 25,000 x 4.3% = USD 1,075
- Section 301: 25,000 x 25% = USD 6,250
- Section 232: 25,000 x 50% = USD 12,500
- MPF: 25,000 x 0.3464% = USD 86.60
- HMF: 25,000 x 0.125% = USD 31.25
- Total US charges: USD 19,942.85 (79.8% 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: since 4 June 2025 steel and aluminium (and their listed derivatives) carry 50%, with UK-origin goods held at 25%. Both stack: a Chinese-origin steel fitting can carry HTSUS + Section 301 + Section 232 in the same entry. Rates are set by presidential proclamation, so confirm the current HTS Chapter 99 heading before filing.
Is there still a USD 800 de minimis exemption in 2026?#
No, not for commercial shipments. From 29 August 2025 the United States suspended duty-free de minimis treatment under Section 321 for goods from all countries, so low-value commercial parcels now pay the applicable duties and need an entry. The USD 800 statutory figure still exists in the law, but the suspension means you should not promise duty-free entry for low-value shipments. Check current CBP guidance for the entry type and any postal-shipment rules.
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.