Your goods leave Canada classified under a six-digit HS code. They cross into the United States and suddenly you're dealing with a ten-digit HTS number, a different set of classification rules, potential Section 301 tariffs, and a legal standard called "reasonable care" that puts the liability squarely on the importer. Same product, same box, completely different compliance universe.
If you're shipping cross-border regularly and you assume the Canadian tariff classification just carries over, you're setting yourself up for a problem. This post explains exactly what changes at the border and what you need to do about it.
The Six-Digit Foundation: What Canada and the U.S. Actually Share
Both Canada and the United States use the Harmonized System, the international classification framework maintained by the World Customs Organization. Every country that's signed on uses the same first six digits. That's the HS code. Those six digits describe the product in broad terms and they're the same whether you're filing in Ottawa, Washington, Brussels, or Tokyo.
So if you're exporting wooden furniture frames classified under HS 9401.90 in Canada, the first six digits of the U.S. number will also be 9401.90. That part isn't the issue.
The issue is everything after those six digits.
What the U.S. Adds: Four More Digits and a Whole Lot of Consequences
The U.S. Harmonized Tariff Schedule, the HTSUS, extends classification to ten digits. The seventh and eighth digits are the U.S. subheading, which narrows the product description further. The ninth digit is a "check digit" used for system validation. The tenth digit is the statistical suffix, used by the Census Bureau for trade data.
For filing purposes with CBP, you need the full ten-digit number. And those last four digits aren't cosmetic. They determine your duty rate, whether you're subject to antidumping or countervailing duties, whether Section 301 tariffs apply, and what partner government agency requirements get triggered.
A furniture importer we worked with was classifying a line of upholstered chairs correctly at the six-digit level. When the U.S. broker drilled down to the ten-digit HTS, they landed on the wrong subheading and missed a Section 301 tariff exposure of 25 percent. On a $300,000 shipment, that's a $75,000 error. CBP caught it on a CF-28 request for information. The importer paid back duties plus interest.
The General Rules of Interpretation: Different Application, Same Text
Canada and the U.S. both use the General Rules of Interpretation, the GRIs, to classify goods. The text is essentially identical. But the way CBP applies them, and the rulings that have built up around them, can lead you to a different subheading than the CBSA would.
GRI 1 says you classify by the terms of the headings and any relevant section or chapter notes. GRI 3 covers goods that could go in two or more headings. GRI 6 applies the same logic to subheadings. This is where things get country-specific.
The U.S. also has the Additional U.S. Rules of Interpretation, which appear right at the front of the HTSUS. These are rules that apply only in the United States. The most important one for most importers is Additional U.S. Rule 1(b), which says that for goods classified by use, the controlling use is the principal use in the U.S. at the time of importation. Not the use in Canada. Not the intended use of your specific customer. The principal use of that class of goods in the U.S. market.
That distinction has tripped up Canadian exporters more than once, particularly in categories like food preparations, textile articles, and industrial equipment where "use" provisions appear in the tariff.
CBP Rulings and the CROSS Database
One of the most useful tools available to U.S. importers is the CBP rulings database, known as CROSS. It's public and searchable by product description, HTS number, or keyword.
Before you finalize a classification on a new product line, search CROSS. If CBP has already ruled on a product that's substantially similar to yours, that ruling tells you how they're going to classify it. It's not legally binding on your specific entry, but if you classify contrary to a published ruling on an identical product and CBP finds it, you'll have a hard time arguing reasonable care.
You can also request your own binding ruling from CBP before you import. The ruling is legally binding on CBP for your specific goods. It protects you. It takes time, sometimes several months, but for high-volume or high-value product lines it's worth it. See our page on advance rulings for how the process works on both sides of the border.
Reasonable Care: The Standard That Puts It on You
Under 19 U.S.C. 1484, the importer of record is legally responsible for using reasonable care to classify goods correctly, determine the correct value, and comply with all applicable laws. CBP doesn't have to prove you were negligent in a criminal sense. They just have to show you didn't exercise reasonable care.
What does reasonable care look like in practice? CBP has published guidance on this. It includes things like: consulting a licensed customs broker, researching the tariff schedule, checking CROSS for relevant rulings, and documenting your classification rationale. If you're just copying a code from a supplier's invoice and filing it without any verification, that's not reasonable care.
The penalties for getting this wrong are real. Under 19 U.S.C. 1592, a negligence violation can cost you up to the domestic value of the merchandise. For gross negligence, it's up to twice the lawful duties owed. Fraud carries penalties up to four times the duties. Even at the negligence level, on a $500,000 shipment, you're looking at exposure that can end a small importing business.
Honestly, most Canadian exporters selling into the U.S. assume their American customer's broker is handling this. Sometimes they are. But if you're the importer of record, it's your problem legally, regardless of who filed the entry.
Section 301, Section 232, and AD/CVD: The Tariff Layers Nobody Warned You About
Here's where cross-border shippers get hurt most often right now. The base HTSUS duty rate might be zero or two percent. But stacked on top of that, depending on the product and the country of origin, you might also owe:
- Section 301 tariffs, which were originally imposed on Chinese-origin goods starting in 2018 and have been expanded and modified multiple times since. As of September 2026, rates on many categories remain at 25 percent or higher, with some electronics and strategic goods at 50 percent. These apply based on the HTS number and the country of origin.
- Section 232 tariffs, which apply to steel and aluminum products on national security grounds. Canadian steel and aluminum have had a complicated history with these measures. Check the current status before you assume Canadian origin exempts you.
- Antidumping and countervailing duties, which are product and country specific, can run from a few percent to several hundred percent, and are assessed based on the HTS number and the origin of the goods. Worth flagging right now: the CBSA launched investigations this month into alleged dumping and subsidizing of truck and bus tires and paperboard cups and containers from China. If those investigations result in Canadian findings, CBP may have parallel AD/CVD orders already in place on the U.S. side. If you're importing either of those product categories into the U.S., check the AD/CVD order database before your next shipment.
All of these additional duties are triggered by the HTS number. If you're on the wrong ten-digit code, you might be paying duties you don't owe, or worse, not paying duties you do owe and getting hit with a penalty later.
Pull up your last ten entries into the U.S. and look at whether any additional tariff columns were assessed. If you're not sure what you're looking at, ask your broker to walk you through the duty calculation on at least one entry. You should understand what you're paying and why.
USMCA and the Origin Question
If your goods qualify under USMCA, you can claim preferential tariff treatment, potentially zero duty, on eligible products. But USMCA qualification depends on the HTS classification of both the finished good and the inputs. Specifically, many USMCA rules of origin are tariff-shift rules: the finished product has to be classified in a different HTS heading or subheading than the non-originating materials used to make it.
If you've got the HTS number wrong, your tariff-shift analysis is wrong. Your USMCA claim is wrong. And if CBP audits it, you're looking at back duties on every shipment where you claimed the preference incorrectly, plus potential penalties.
The certification of origin under USMCA is a self-certification. You're making a legal representation. That representation has to be based on an actual analysis of the rules of origin for the correct HTS number. "My supplier told me it qualifies" is not going to hold up in a CBP verification.
Partner Government Agency Requirements: The Other Agencies at the Border
CBP isn't the only agency with jurisdiction over goods entering the U.S. Depending on the HTS classification, your shipment might also need to comply with requirements from the FDA, USDA, EPA, FCC, CPSC, or other agencies. These are called Partner Government Agency, or PGA, requirements, and they're filed through ACE, the Automated Commercial Environment.
The HTS number is what triggers the PGA flags in ACE. Wrong number, wrong flags. You might clear a shipment that should have had an FDA prior notice filing. Or you might get held for a USDA inspection on goods that don't actually require one, because the HTS code you used is associated with regulated agricultural products.
Food products, medical devices, electronics, chemicals, and anything with a plant or animal component are the categories where PGA requirements most often catch people off guard. If you're exporting any of these into the U.S., verify the PGA requirements for the correct ten-digit HTS number before the first shipment, not after CBP puts a hold on your container.
Practical Steps Before Your Next U.S. Shipment
- Start with the six-digit HS code from your Canadian classification, but don't stop there. Use it as a starting point to find the right HTSUS heading, then work through the subheadings using the GRIs and the Additional U.S. Rules.
- Search CROSS for your product. The database is free and public at rulings.cbp.gov. If there are relevant rulings, read them. If they support your classification, document that. If they point somewhere else, take that seriously.
- Check the additional duty columns. Look at columns for Section 301, Section 232, and any active AD/CVD orders. The USITC maintains the official HTSUS at hts.usitc.gov. The AD/CVD order database is at enforcement.trade.gov.
- Verify USMCA eligibility against the correct HTS number. Don't rely on a general statement from a supplier. Look at the specific rule of origin for that subheading in Annex 4-B of the agreement.
- Check PGA requirements for the ten-digit number. CBP's ACE portal has a PGA message set reference that lists which agencies have requirements for which HTS codes.
- Document your classification rationale. Write it down. What sources you consulted, what rulings you reviewed, why you landed on that number. This is your reasonable care file. If CBP ever asks, you want to be able to show your work.
For detailed information on specific HS headings and how they map to HTSUS subheadings, see our tariff reference pages, which include notes on common classification issues by product category.
Frequently Asked Questions
If my Canadian broker classified something correctly for CBSA purposes, can I just use that code for U.S. imports?
No. The six-digit HS heading will likely be the same, but the U.S. subheadings from the seventh digit onward are determined by U.S. rules, U.S. legal notes, and CBP rulings. Your Canadian classification is a useful starting point, nothing more. You still need to work through the HTSUS to get to the right ten-digit number.
Who is responsible for the HTS classification on a U.S. entry?
The importer of record. Always. Your customs broker files the entry on your behalf, but the legal responsibility under 19 U.S.C. 1484 sits with you. If the broker makes an error, you can pursue them for damages, but CBP will come after you for the duties and penalties. Make sure you understand what your broker filed and why.
How do I know if my product is subject to Section 301 tariffs?
Section 301 tariffs are listed in the HTSUS under special tariff subheadings, primarily in Chapter 99. You look up your ten-digit HTS number, then check whether any Chapter 99 provisions apply based on the origin of the goods. The USTR maintains lists of covered products. If your goods originate in China, this is not optional research.
Can I get a binding ruling from CBP before I start importing?
Yes. You submit a ruling request to CBP's National Commodity Specialist Division with a detailed description of the product, samples if applicable, and your proposed classification with supporting rationale. CBP issues a binding ruling letter that protects you as long as the goods match the description. It typically takes 30 days, though complex cases can take longer. For high-volume product lines, it's worth doing. See our advance rulings page for more detail on the process.
My supplier says the goods qualify for USMCA. Is that enough?
No. The supplier can certify origin, and that certification has to be based on an actual analysis of the rules of origin. But you, as the importer, are responsible for having a reasonable basis to believe the claim is valid before you use it. If CBP audits the USMCA claim and finds it doesn't hold up, you owe back duties on every shipment where you claimed the preference. Ask your supplier for the tariff-shift analysis or the regional value content calculation that supports the certification. If they can't provide it, be cautious.
What's the difference between the HTS number and the Schedule B number?
The Schedule B is used for U.S. export reporting through the Electronic Export Information system. It's maintained by the Census Bureau. The HTSUS is used for import classification with CBP. The first ten digits are usually the same, but they're different systems for different purposes. When you're importing into the U.S., you use the HTSUS. When you're exporting from the U.S., you use Schedule B. As a Canadian exporter, you're dealing with the HTSUS on the import side.