Customs and documents on the Korea–US lane

The sequence at a glance

Leaving Korea

1. Classify the goods. Korea uses a 10-digit HSK tariff code. The first six digits follow the international Harmonized System and should match the classification used at destination. The remaining digits are national, so a Korean HSK code and a 10-digit US HTSUS code for the same product usually differ after the sixth digit. A six-digit mismatch between the export declaration and the US entry is a common reason for questions from either customs service.
2. File the export declaration. The exporter or its customs broker (관세사) files it electronically through the Korea Customs Service's UNI-PASS system. Once it is accepted, the goods must normally be loaded within 30 days.
3. Keep the export declaration certificate. The accepted declaration (수출신고필증) supports VAT zero-rating, duty drawback and any later origin verification.
4. Check controls. Strategic items and dual-use technology need an export license under Korea's own export control rules before they ship.

Getting the HS code right

Classification drives the duty rate, the FTA rule of origin that applies, and whether another agency has a say at the border. A few habits prevent most problems: See HS code classification for why only six digits are international and what the 2028 revision changes.

• Classify from what the product is and does, not from the supplier's catalog name.
• Agree the six-digit heading between exporter and importer before the first shipment, and write it on the commercial invoice.
• When the classification is genuinely uncertain, ask for a binding ruling: CBP issues rulings through its CROSS system, and the Korea Customs Service runs an advance classification process.
• Recheck codes when the Harmonized System is amended. The World Customs Organization revises it periodically, and national schedules follow.

Claiming FTA origin

The Korea–US Free Trade Agreement (KORUS), in force since 2012, gives preferential treatment to goods that meet its rules of origin. A claim can be based on a certification of origin completed by the importer, exporter or producer. No official form is prescribed, but the certification must contain the required data elements, and whoever certifies must be able to support it with records, because either customs administration can verify the claim afterwards. The details are in the KORUS certificate of origin guide.

Two cautions. First, qualifying under the rules of origin is a product-specific question, not a matter of where the goods were shipped from. Second, preferential FTA treatment does not necessarily exempt goods from additional US duties imposed under other authorities, such as the Section 232 duties on steel, aluminum and vehicles. Check both before pricing a sale.

For Europe, the EU–Korea FTA uses an origin declaration on the invoice or another commercial document. For consignments above EUR 6,000, only an approved exporter may make it. See the EU–Korea origin declaration guide.

Arriving in the United States

Air shipments are subject to advance electronic cargo data requirements that the carrier and forwarder handle, but the data comes from your documents, so it has to be accurate. For the EU, the Import Control System 2 (ICS2) similarly requires safety and security data before arrival.

Low-value shipments no longer skip entry

Until August 2025, most shipments valued at $800 or less could enter the US free of duty under the "de minimis" rule (Section 321). The US suspended that treatment for goods from all countries effective August 29, 2025, and CBP published regulations in June 2026 to keep it suspended indefinitely. Separately, a 2025 statute repeals the exemption for commercial shipments from July 1, 2027. Samples, spare parts and e-commerce orders from Korea therefore need an entry and pay any applicable duty, whatever their value. The practical consequences are in the de minimis guide.

The document set

• Commercial invoice: seller, buyer, description, HS code, value, currency, Incoterms rule
• Packing list: packages, weights, dimensions and marks, consistent with the invoice
• Bill of lading (ocean) or air waybill (air)
• Export declaration certificate from UNI-PASS
• Origin certification where a preferential rate is claimed
• Permits and certificates the product needs, such as export licenses or regulatory approvals

Most customs holds come from documents that disagree with each other. The shipping documents checklist lists the fields that must match, and keeping these documents attached to the shipment record, rather than scattered across email, is covered in tracking and custody.

Common questions

Who pays US duty on goods shipped from Korea?

The importer of record. Under most Incoterms rules that is the buyer. Under DDP it is the seller, which means a Korean exporter selling DDP takes on US entry, duty and the risk of tariff changes. See Incoterms 2020 for Korea trade.

Can a Korean company be the US importer of record?

A non-resident company can act as importer of record, but it needs a customs bond and usually a US agent or broker to file for it. Discuss the setup with a licensed US customs broker before you sell on DDP terms.

What happens if the export declaration and invoice disagree?

The shipment may be questioned in Korea or at destination, and an origin or drawback claim built on the declaration becomes harder to defend. Amend the declaration through your 관세사 rather than leaving the mismatch in place.

Is air cargo subject to ISF?

No. ISF applies to ocean cargo. Air shipments have their own advance data requirements, which the carrier and forwarder file.