More sellers are moving the last process to Thailand or Vietnam and shipping to the US from Laem Chabang or Ho Chi Minh City. Freight and duty often look better — and one thing gets missed: US Customs decides where the goods were “made” by where they became the article they are now, not by where the last screw was turned.
The rule: substantial transformation
US origin turns on substantial transformation: after processing in a country, does the article become a new and different article of commerce, with a new name, character or use? Assembly, packing, labelling and simple mixing usually do not qualify.
This is not academic. It decides three things: the origin marking on the goods (19 U.S.C. §1304), the duty rate that applies — including additional duties on China-origin goods — and, for some products, whether the goods may be imported at all.
Case one: Chinese panels, assembled in Thailand
A factory in Rayong imports panels from China that are already cut, edge-banded and drilled. In Thailand it fits hardware and packs the unit for export to the US. In that shape, CBP is likely to treat the goods as China-origin: fitting hardware has not changed the name, character or use of the panel.
The consequence comes twice. The carton must be marked with the China origin, and if the HTS code sits on a China tariff list, duty is calculated on China origin. To change the answer, the Thai process must add real transformation, or the component sourcing has to change. When it is genuinely unclear, ask CBP for an origin ruling before shipping, not after.
Case two: Chinese fabric, cut and sewn in Vietnam
Textiles and apparel have their own origin rules in the US (19 CFR 102.21), and they do not follow the general substantial-transformation test exactly. Whether a garment cut and sewn in Vietnam from Chinese fabric is Vietnam-origin depends on the style and the HTS line — it cannot be answered from experience alone.
In practice, keep three things on file: fibre and fabric origin documents, cutting and sewing records, and a written origin analysis for the HTS code. Without them, an inspection is hard to answer.
What clearance asks for
- Commercial invoice: real unit price, Incoterm, origin statement
- Packing list: pieces, gross weight, volume, carton marks
- ISF 10+2: filed 24 hours before loading, and that applies to Thai and Vietnamese load ports too
- Importer setup: EIN, customs bond, broker authorisation
- Product compliance: FDA, USDA, FCC or CPSC depending on the goods
- Origin evidence: factory records, process description, a ruling where needed
Choosing the lane
| Origin | Destination | Indicative transit | Fits |
|---|---|---|---|
| Laem Chabang | Los Angeles / Long Beach | 14–20 days | Eastern Thailand factories, mainly FCL |
| Ho Chi Minh City (Cat Lai / Cai Mep) | US west coast | 14–19 days | Southern Vietnam, LCL and FCL |
| Haiphong | US west coast | 16–22 days | Northern Vietnam electronics and furniture |
| Southeast Asia | US east coast (Suez or Panama) | 28–36 days | East coast warehouses, DDP door delivery |
| Bangkok / Ho Chi Minh City | US airports | 3–6 days | Replenishment, samples, high-value cargo |
Transit figures are indicative; the carrier, season and port congestion decide. Choose the lane backwards from the latest warehouse arrival date, then compare price.
The other direction: US to Southeast Asia
The lane runs both ways. US materials, machinery and returned goods go back to Thai or Vietnamese factories, or stock is transferred from a US warehouse into Southeast Asia, usually via Singapore or Port Klang. On the return leg, check the import licence and VAT registration requirements of each Southeast Asian country first.
A checklist you can work from
- Origin analysis before booking, not during clearance
- Carton marking that matches the declared origin
- ISF filed 24 hours before loading
- Invoice, packing list and origin evidence together
- Duty modelled on two axes: origin and HTS code
If you run a factory in Thailand or Vietnam, or are thinking of moving the last process there, send us the process flow and component sources. We will model origin and duty before you commit.