US Customs Country Codes: Official List and Filing Rules

U.S. Customs and Border Protection uses the ISO 3166-1 Alpha-2 country code system on nearly every import filing that runs through the Automated Commercial Environment. The US customs country codes you need are two letters long, drawn from that international standard, and published by CBP in Appendix C of the Automated Export System Trade Interface Requirements.¹ The importer of record is responsible for reporting them accurately, and mistakes can produce rejected filings, wrong duty calculations, and penalties.²

What the Codes Look Like

Every country and territory gets a two-letter code. CN is China. DE is Germany. MX is Mexico. The same list runs through international shipping and banking, so most importers already recognize the codes before they ever file with CBP.¹

CBP maintains its own adopted version of the ISO list, adapted for U.S. trade reporting. Not every code in the international standard is valid in CBP’s systems, and a few codes exist only for U.S. reporting situations. If you enter a code that ISO recognizes but CBP has not adopted, ACE will reject the filing.

Where to Find the Official List

The authoritative list is Appendix C of the AES Trade Interface Requirements, published on CBP’s website in the AES section alongside other technical appendices such as port codes and units of measure.³⁴

A parallel reference is the U.S. Census Bureau’s Schedule C, which lists country codes for foreign trade statistics. Schedule C shows both a four-digit Census code and the two-letter ISO code for each country, and it covers every reportable destination.⁵ Both lists are updated periodically, with revisions issued as supplements to the Harmonized Tariff Schedule.⁶ Check the current version before a filing; a code that was valid last cycle can be retired.

Filings That Require Country Codes

Country codes appear on several filings across the import process. A code that is right on one form and wrong on another creates a discrepancy that can flag the entry for examination or delay liquidation.

Entry Summary (CBP Form 7501)

The entry summary determines duties, taxes, and fees. It requires at least two country code fields: country of origin (where the goods were manufactured, produced, or grown) and country of export (the last country from which the goods were shipped before arriving in the United States). These often differ. Goods manufactured in Vietnam but shipped through a distribution hub in Singapore would show VN as country of origin and SG as country of export. When multiple entries share both the same origin and the same export country, CBP may allow consolidation onto a single entry summary.⁷

Importer Security Filing (ISF-10)

For ocean cargo, the importer must file an ISF (the “10+2”) before goods are loaded onto the vessel at the foreign port. Country of origin is one of the required data elements and must reach CBP no later than 24 hours before loading.⁸ That deadline is earlier than the entry summary itself, so you have to lock in the correct country code before the goods even leave the foreign port. Inaccurate or late ISFs can lead to liquidated damages assessed against your customs bond.

Electronic Manifests and Former Section 321 Entries

Carriers filing ACE e-Manifests must report country codes for the vehicle or vessel’s country of registration. For shipments that used to qualify for duty-free treatment under Section 321 as low-value imports, the two-letter country of origin code is still a mandatory data element.⁹ Since February 2026, an executive order has suspended duty-free de minimis treatment for all shipments regardless of value or country of origin, so these entries now face applicable duties and the origin code directly affects what is owed.¹⁰

Determining Origin When Goods Cross Multiple Countries

Picking the right code is simple when a product is made entirely in one country. It gets harder when raw materials come from one place, processing happens in a second, and final assembly in a third. The general rule for most goods is the substantial transformation test: the country of origin is the last country where the product underwent a fundamental change in its name, character, or use.¹¹

Repackaging, relabeling, or minor assembly does not count. Fabric imported from India, then cut and sewn into finished garments in Bangladesh, will likely take Bangladesh as its origin because the sewing operation transforms it. If Bangladesh only attaches buttons and a label, India remains the origin country.

Canada and Mexico follow a different framework. Under the USMCA, origin for marking purposes is determined by the tariff shift rules in 19 CFR Part 102 rather than the substantial transformation test.¹¹ Those rules ask whether the product’s tariff classification changed as a result of processing in a USMCA country. The two methods can produce different origin answers for the same product, so it matters which one applies.

Physical marking on the goods themselves has to match. Every imported article, or its container, must be marked with the English name of the origin country in a way that is conspicuous and legible to the final purchaser. If CBP finds unmarked or mismarked goods, the importer receives a notice to correct the marking, re-export, or destroy the merchandise.¹¹

Codes for Territories and Unknown Origin

Schedule C assigns distinct two-letter codes to U.S. territories even though they are domestic for many legal purposes. Puerto Rico is PR, the U.S. Virgin Islands are VI, Guam is GU, American Samoa is AS, and the Northern Mariana Islands are MP.⁵ These are separate from the standard US code and are used to track goods moving between the territories and the U.S. customs territory.

CBP allows the code UN for unknown country of origin in narrow situations. The prominent example is derivative aluminum products subject to Section 232 tariffs: if the country where the aluminum was smelted or cast cannot be determined, the importer reports UN on the relevant declaration record. Using UN carries a cost. CBP assesses the highest applicable Section 232 duty rate on that entry, currently the 200 percent rate applied to Russian-origin aluminum, on the assumption that unknown origin carries the greatest trade risk.¹² Outside of that specific scenario, entering a vague or placeholder code will almost certainly draw a rejection or a request for information.

Country Codes and Trade Agreement Claims

Claiming a preferential duty rate under a free trade agreement requires the country of origin code to match a country eligible for that agreement, and it requires a Special Program Indicator (SPI) prefix on the 10-digit HTS number. The SPI tells CBP which trade program you are invoking.¹³

Some of the most commonly used SPIs:

CA or MX for goods of Canada or Mexico under the USMCA
A for the Generalized System of Preferences for qualifying developing countries
AU for the United States-Australia Free Trade Agreement
KR for the United States-Korea Free Trade Agreement
IL for the United States-Israel Free Trade Agreement
E for the Caribbean Basin Economic Recovery Act

Using an SPI that does not match the reported country of origin, or claiming a trade agreement benefit for goods that do not actually originate in an eligible country, is a common source of penalty actions. Goods entered under certain trade agreement SPIs are also exempt from the Merchandise Processing Fee, so the financial stakes of aligning the country code and the SPI are higher than many importers assume.¹³

Penalties for the Wrong Code

An incorrect country of origin code can be treated as a material misstatement on a customs entry. Federal law prohibits entering goods using any false or misleading information, whether the error results from fraud, gross negligence, or simple negligence. The penalty caps scale with culpability:¹⁴

Fraud: a civil penalty up to the full domestic value of the merchandise.
Gross negligence: up to the lesser of the domestic value or four times the duties the government was deprived of. If the error did not affect duties, the cap is 40 percent of the dutiable value.
Negligence: up to the lesser of the domestic value or two times the lost duties. If no duty impact, the cap is 20 percent of the dutiable value.

There is a carve-out. Isolated clerical errors and honest mistakes of fact are not violations unless they form a pattern of negligent conduct. A one-time typo transposing TW (Taiwan) and TH (Thailand) is unlikely to draw a penalty on its own. The same error repeated across dozens of entries because nobody caught it can be treated as negligence.¹⁴ Where a wrong code causes the entry to claim benefits it should not receive, such as a lower duty rate under a trade agreement or avoidance of antidumping duties, financial exposure climbs quickly.

Correcting a Country Code After Filing

If you spot an incorrect country code on an entry summary that has not been liquidated yet, the fix is a Post-Summary Correction (PSC), the only electronic method for correcting entry summary data before liquidation. A PSC can be submitted within 300 days from the date of entry, or up to 15 days before the scheduled liquidation date, whichever comes first. If CBP has granted a liquidation extension, the 300-day limit does not apply, but you still have to file at least 15 days before the new liquidation date. PSCs filed outside those windows are automatically rejected.¹⁵

Both revenue-affecting changes (those that alter duties) and non-revenue changes (corrections to statistical data) can be submitted through a PSC. A country of origin correction that shifts goods into or out of a trade agreement rate, or changes exposure to antidumping or countervailing duties, is a revenue change and will recalculate what is owed.¹⁵

Once the entry has been liquidated, the PSC window closes. The remedy at that point is a formal protest under 19 CFR Part 174, which must be filed within 180 days after notice of liquidation.¹⁶ Protests cover decisions involving clerical errors, mistakes of fact, and other inadvertent errors that worked against the importer. A protest is more formal than a PSC and typically runs through a customs broker or trade counsel, but it preserves your right to recover overpaid duties caused by an origin code mistake. Missing the 180-day protest deadline generally forecloses your ability to challenge the liquidation.

1
U.S. Customs and Border Protection. Appendix C – ISO Country Codes
2
Office of the Law Revision Counsel. 19 USC 1484 – Entry of Merchandise
3
U.S. Customs and Border Protection. How To Use The Automated Commercial Environment (ACE) – AES
4
U.S. Customs and Border Protection. ACE AESIR Appendix C – Country and Territory Codes
5
Census Bureau. Schedule C – Country Codes and Descriptions
6
U.S. International Trade Commission. Schedule C, Classification of Country and Territory Designations for U.S. Import Statistics
7
GovInfo. 19 CFR Part 142 – Entry Process
8
eCFR. 19 CFR Part 149 – Importer Security Filing
9
U.S. Customs and Border Protection. Section 321 Programs
10
The White House. Continuing the Suspension of Duty-Free De Minimis Treatment for All Countries
11
eCFR. 19 CFR Part 134 – Country of Origin Marking
12
U.S. Customs and Border Protection. CSMS 65340246 – GUIDANCE: Section 232 Aluminum Import Monitoring
13
Harmonized Tariff Schedule of the United States. General Statistical Notes
14
Office of the Law Revision Counsel. 19 USC 1592 – Penalties for Fraud, Gross Negligence, and Negligence
15
U.S. Customs and Border Protection. Post Summary Corrections
16
eCFR. 19 CFR Part 174 – Protests