Country of origin on past entries: which rule applies, and what an error costs

Why does origin on a past entry need its own check?

Block 10 of Form 7501 holds one country code per entry, or "MULTI" with a code for each line in column 31 prefixed with "O". That code decides more of the duty on a line than any field except the HTS code. It decides whether Section 301 applies, which economy's rate applies under the forced-labor Section 301 action, which IEEPA order applied to older entries, whether an AD/CVD order covers the goods, and whether a trade-agreement rate is even possible.

It is also the field most often filled from the wrong document: a trading company's invoice address, the port of loading or the supplier's head office instead of the country of origin. The basic block 10 and block 14 check is on the post-entry audit pillar; this page is about the harder question behind it.

The harder problem is that "origin" is not one rule. The same line can have one origin for marking, another for Section 301 and a third answer to whether it qualifies for USMCA. An audit that checks only one of them misses the others.

Which origin rule applies to which question?

Two things follow from the table. The USMCA test answers whether a lower rate applies, not which country the goods are a product of. And for goods of Canada and Mexico, the country marked on the goods can legitimately differ from the country of origin used for Section 301.

What is substantial transformation, in practice?

A substantial transformation happens when processing produces a new article with a new name, character or use. CBP's rulings apply it case by case on the totality of the evidence, and several patterns repeat across them.

• Simple assembly rarely counts. CBP has held that minimal or simple assembly, as opposed to complex or meaningful assembly, generally does not change origin. The factors it lists include the number of components, the number of operations, and the time, skill, detail and quality control the work needs.
• A predetermined use cuts against a change in use. When a part is made for one finished product, assembling it into that product does not give it a new use.
• Processing that changes the material can count. In HQ H335139 (May 1, 2024), aluminum profiles from China were cut, punched, heat-treated and aged in Mexico, which changed their strength and hardness, and then assembled into vehicle crash boxes. CBP held the crash boxes were of Mexican origin for Section 301.
• Facts decide, and incomplete facts decide wrongly. In that same case, an earlier New York ruling had found the crash boxes to be Chinese. CBP's headquarters office reversed it after the importer described the heat treatment in detail and CBP's laboratory confirmed the change in the metal.

The lesson for an audit is that origin is a documented conclusion, not a field to copy from the supplier. The bill of materials, where each component was made, and what each production step does to the goods are the evidence.

Why can one line have two origins?

HQ H300226 (September 13, 2018) is the clearest example. A brushed electric motor for car door locks was assembled in Mexico from three components made in China: the stator or rear housing, the rotor or armature assembly, and the end cap assembly. CBP applied the Part 102 rules because Mexico was then a NAFTA country, found that the Chinese components shifted tariff classification, and held the motor's origin for marking to be Mexico. For Section 301, CBP applied substantial transformation instead, found that assembling three parts did not transform them, and held the motor to be a product of China, subject to the Section 301 duty under heading 9903.88.01.

Today the same split rests on 19 CFR 134.1(b) and 102.0, which apply the Part 102 rules to marking goods of USMCA countries. So a motor correctly marked "Made in Mexico" can still owe Section 301 duties as a product of China. Neither result is a mistake; they answer different questions.

A USMCA claim adds a third question. Whether the motor is an originating good under 19 U.S.C. 4531 depends on whether it satisfies the product-specific rule for its heading in Annex 4-B of the USMCA (19 U.S.C. 4531(c)(1)(B)), which is a different test from either of the other two. A valid USMCA claim lowers the rate, but it does not answer the Section 301 question on its own. In the request that led to HQ H335139, CBP addressed classification, USMCA preference and the Section 301 origin separately, and changed only the Section 301 answer.

What does an origin error do to the duties on past entries?

The effect depends on the entry date, because the programs that key off origin have changed several times. Each with its instrument:

• Section 301, China. The China actions apply to "articles the product of China" on the USTR lists, at 25 percent under headings such as 9903.88.01 to 9903.88.04 and 7.5 percent under 9903.88.15, as printed in the 2026 HTS. A Chinese product reported with another origin underpays the full Section 301 rate. A non-Chinese product reported as Chinese overpays it.
• Section 301, forced labor, entries from July 24, 2026. USTR's notice (91 FR 47318) adds 10 percent on products of some economies and 12.5 percent on others; China and Vietnam are at 12.5 percent, Canada, Mexico and India at 10 percent. Products of Canada or Mexico entered free of duty under USMCA are exempt (headings 9903.05.93 and 9903.05.94). An origin error can move a line between rates, and a failed USMCA claim on Canadian or Mexican goods loses the exemption as well as the preferential rate.
• IEEPA, entries before February 24, 2026. The IEEPA duties applied by the country the goods were a product of, under separate orders with different rates. The order on Canada counted goods as products of Canada under either the Part 102 rules or the last substantial transformation (90 FR 11423). Executive Order 14389 ended the IEEPA duties, and CBP stopped collecting them for goods entered from 12:00 a.m. eastern time on February 24, 2026 (CSMS # 67834313). For entries before that date, origin decides which IEEPA amount was paid and therefore what can be claimed back; see which IEEPA entries qualify for a refund.
• Section 232. Steel and aluminum duties apply by product from every country, so origin usually does not switch them on or off. Country-specific treatment is the exception: Proclamation 10947 raised the rates to 50 percent from June 4, 2025 while keeping articles of the United Kingdom at 25 percent. For entries from April 6, 2026, Proclamation 11021 (91 FR 18201) ties the lower UK rates (25 percent, or 15 percent for the articles in its Annex I-B) to UK products whose steel was melted and poured, or whose aluminum was smelted or most recently cast, in the United Kingdom. So a UK-rate line now needs two facts: UK origin and UK metal. A claim of UK origin on goods that are not of UK origin, or on UK goods made from other countries' metal, underpays the difference. The melt-and-pour and smelt countries in blocks 21 to 24 are separate fields and should agree with the mill certificates.
• AD/CVD. An order covers goods by product scope and country. Whether goods finished in a third country from the order country's inputs are covered is decided by Commerce, in a scope ruling or a circumvention inquiry (19 CFR 351.225 and 351.226), and Commerce may reach a different origin than a CBP ruling did (19 CFR 351.225(j)). A line that a CBP ruling treats as non-Chinese for Section 301 can still fall inside a Chinese AD/CVD order; check the order's scope and any Commerce ruling for the product before relying on block 10.
• Marking. Under 19 U.S.C. 1304(i), an article not properly marked at importation, and not remedied under CBP supervision before liquidation, owes an additional 10 percent ad valorem duty.

You can check the stack for a code, an origin and a date with the duty calculator, and how the layers combine on one line is on why your entry shows the wrong duty stack.

A worked line: a motor assembled in Mexico from Chinese parts

Take an illustrative line, with the facts of HQ H300226: an electric motor under HTS subheading 8501.10.40, assembled in Mexico from Chinese components by a simple assembly, entered August 10, 2026, entered value $50,000. Assume it qualifies for USMCA, so its base rate is free, and that no Section 301 product exclusion applies.

The marking "Made in Mexico" on this motor can be correct under the Part 102 rules while the Section 301 origin is China. The $18,750 difference is an underpayment on every entry of the motor since July 24, 2026, and the Section 301 China list part of it runs back further. If the USMCA claim fails as well, the general rate for the subheading, 4.4 percent in the 2026 HTS, applies on top. Whether a real product transforms, and whether it meets the USMCA rule, are factual questions; this table only shows how much rides on the answers.

How do you audit origin across an entry export?

1. List every line by part number, supplier, origin and exporting country. Lines where the origin equals the exporting country by default, for goods made by a trading company's suppliers, are the first to check.
2. Flag parts whose origin changes between entries without a change of supplier or process. One of the entries is wrong.
3. Pull the bill of materials and process description for products assembled or finished outside the country where their main components were made. Decide substantial transformation from those facts, and write down the reasoning.
4. Separate the three questions on any line from Canada or Mexico: marking under Part 102, Section 301 origin under substantial transformation, and USMCA originating status under 19 U.S.C. 4531, each with its own support. A missed USMCA claim is its own finding; see unclaimed USMCA preference on past entries.
5. Recompute the stack for the corrected origin on each entry date and note the difference per line.
6. Route each finding by the entry's status. Overpayments go by post-summary correction before liquidation or by protest within 180 days after it. Underpayments go by post-summary correction before liquidation or by prior disclosure. See the post-entry audit pillar for the route table, and confirm filings with a licensed customs broker or trade counsel.
7. For products you keep importing, consider a ruling. CBP's eRulings program accepts country of origin and marking requests. How rulings work on past entries is covered in binding rulings and CROSS for past entries.

How does TariffSense fit into an origin check?

TariffSense reads the origin, exporting country and line codes from Form 7501s and broker entry exports, flags parts whose origin changes between entries and lines where origin and exporting country are reported the same for goods bought through an intermediary, and recomputes each line's Chapter 99 stack for its origin and entry date. Deciding substantial transformation stays with your team, on your production facts. The post-entry audit page describes what goes in and what comes back.

What should you do next on your own entries?

Sort your last twelve months of entries by product and list every product made or finished in one country from components made in another. For each, write down the three answers separately: the country it is marked with, the country it is a product of for Section 301, and whether it is USMCA-originating if it comes from Canada or Mexico. Where the second answer differs from what block 10 says, recompute the Section 301 layers for every entry of that product, and decide the route before the next liquidation date.