Effective August 19, 2026, a new US tariff under Section 338 of the Tariff Act of 1930 applies a 50 percent duty to motor vehicles, dairy, alcohol, and a broad list of other Canadian goods, and unlike earlier US tariffs on Canada, CUSMA-compliant products are not exempt. If your business has been treating a certificate of origin as protection against every US tariff, this one breaks that assumption. This guide covers what Section 338 actually covers, what is excluded, why CUSMA does not help here, and what to check on your own product list before the effective date.
If you sell into the US and have already read our guide on cross-border ecommerce after de minimis, this is the update that guide could not have anticipated: CUSMA paperwork, the single biggest lever that guide recommends, does not reduce this specific tariff.
01. The Quick Answer: What Section 338 Changes
On July 21, 2026, the White House signed three presidential proclamations invoking Section 338 of the Tariff Act of 1930, a provision permitting duties up to 50 percent against a trading partner found to discriminate against US commerce. It is the first recorded use of Section 338 in nearly a century, and it targets Canadian motor vehicles, dairy, and alcoholic beverages, alongside a much wider secondary list of consumer and industrial goods. The tariff takes effect August 19, 2026, 30 days after signing.
The detail that matters most for Canadian sellers: earlier US tariffs on Canada generally excluded goods that qualified as CUSMA-originating, so a certificate of origin was the standard way to reduce exposure. Section 338 does not carve out CUSMA-compliant goods. A covered product pays the 50 percent duty whether or not it qualifies under CUSMA rules of origin.
Why it matters: if your pricing, quotes, or margin planning assume CUSMA compliance protects a product from US tariffs generally, that assumption is now wrong for any product on the Section 338 lists.
02. At-a-Glance: How This Differs From Earlier Tariffs
| Factor | Earlier tariffs | Section 338 (2026) |
|---|---|---|
| Legal authority | Tariffs tied to IEEPA and Section 232 | Section 338 of the Tariff Act of 1930, first used in nearly a century |
| CUSMA-compliant goods | Generally excluded from the tariff | Not excluded, the 50 percent rate applies regardless of origin paperwork |
| Categories covered | Autos, steel, aluminum, and select goods | Motor vehicles, dairy, alcohol, plus a broad consumer and industrial goods list |
| Stated reason | General trade balance and national security claims | Specific discrimination claims on alcohol, dairy, and auto market access |
| Effective date | Varied by proclamation through 2025 | August 19, 2026, 30 days after the July 21 signing |
Why it matters: this is not a rate increase on a familiar rule, it is a different legal mechanism with different exemptions, so advice that applied to previous tariffs does not automatically transfer to this one.
03. Why This Tariff Exists: Three Trade Disputes
The White House framed Section 338 as a response to discriminatory treatment of US goods, and the three proclamations map to three specific disputes. Several Canadian provinces pulled US alcohol products from government liquor store shelves during earlier trade tensions. Canada has granted the European Union better market access terms for dairy products than it grants the US under CUSMA's dairy quota structure. Canada caps the number of US-built vehicles that can enter the Canadian market tariff-free under its own retaliatory measures.
Each proclamation targets the sector tied to its dispute: alcohol, dairy, and motor vehicles. The broader secondary list of goods, covering everything from furniture to cosmetics, extends the tariff's reach well past those three sectors.
Why it matters: because the tariff is framed as retaliation for specific disputes rather than a general trade measure, its scope and duration are tied to whether those disputes get resolved, not to a fixed schedule.
04. What Is Covered by the 50 Percent Tariff
The core categories are motor vehicles and auto parts, dairy products, and alcoholic beverages. The published secondary list extends well beyond those three sectors to include electronics and telecom equipment, furniture and home goods, building materials such as lumber, plywood, doors, and cement, plastics and packaging, clothing, footwear and luggage, toys and sporting goods, machinery and manufacturing inputs, cosmetics and fragrances, and agricultural products including flowers, plants, and seeds.
For a Canadian manufacturer or wholesaler, the practical question is not whether your industry sounds like it belongs on this list, it is whether your product's specific HS code appears on the published schedule. Two products in the same general category can land on opposite sides of the line depending on classification.
Why it matters: a category name is not a safe way to check exposure. Confirm by tariff classification, not by industry.
05. What Is Excluded
Energy products, potash, fish and seafood, and critical minerals are excluded from Section 338. Civil aircraft and qualifying aircraft parts covered under the WTO Agreement on Trade in Civil Aircraft are also excluded. Canadian goods already subject to separate Section 232 tariffs, including steel, aluminum, copper, certain derivative products, and lumber and forestry products, are excluded from Section 338 as well, since those categories already carry their own tariff treatment.
Why it matters: if your product falls under an existing Section 232 tariff, it will not also be hit by Section 338, but it is still tariffed, just under a different rate and rule set that you should already be tracking separately.
06. Why CUSMA Compliance Does Not Help Here
CUSMA rules of origin have been the standard tool Canadian exporters use to reduce or eliminate tariff exposure on shipments to the US, and that remains true for CUSMA trade generally and for several existing tariff programs. Section 338 breaks that pattern on purpose. Because it is framed as a penalty for discriminatory trade practices rather than a standard tariff on non-compliant goods, the proclamations apply the 50 percent duty to covered goods regardless of origin.
This does not make a certificate of origin worthless. It still matters for CUSMA trade broadly and for other tariff programs that do carve out CUSMA-qualifying goods. What changes is that a business cannot assume CUSMA paperwork is a universal shield against every US tariff on Canada. Each tariff program now needs to be checked on its own terms.
Why it matters: a manufacturer that spent the past year getting CUSMA certification in order, expecting it to cover this kind of exposure too, needs to recheck the math specifically for Section 338, not assume the earlier work covers it.
07. What This Means for Your Shopify Pricing
For a covered product, a 50 percent duty is large enough to erase margin entirely if it is absorbed rather than priced in. Sellers using Shopify Markets to manage US-facing pricing should update duty and landed cost calculations for any exposed SKU before August 19, rather than discovering the gap when a US order settles at a loss. Wholesale accounts quoted on older pricing need updated quotes before their next order, not after.
Why it matters: the effective date is fixed and known in advance, which makes this one of the few tariff changes a business can fully price for ahead of time instead of reacting after the fact.
08. Practical Steps Before August 19
- Pull your actual HS codes. Match every SKU you ship to the US against the current Section 338 product lists by tariff classification, not by category name. The lists are specific, and a product that sounds excluded can still be covered.
- Recalculate landed cost before August 19. For any exposed product, model the new duty into your US price or shipping charge now, not after the first order comes in at a loss. A 50 percent duty is large enough to erase margin entirely on thin-margin lines.
- Stop treating CUSMA paperwork as a fix for this one. Keep your certificate of origin on file, it still matters for other tariffs and for general CUSMA trade, but do not expect it to reduce or remove this specific 50 percent duty.
- Update Shopify pricing and wholesale quotes. Adjust US-facing product pricing, Shopify Markets rules, and any open wholesale quotes so a customer is not quoted a price that is already wrong by the time the order ships.
- Flag exposed accounts in your CRM. If you run HubSpot, tag US wholesale accounts buying an affected category so sales and support are giving the same answer when a customer asks why a price changed.
- Bring in a customs broker for gray areas. If a product's classification is genuinely ambiguous, or the exposure is large enough that a wrong guess is expensive, a broker's opinion is worth the fee before the effective date, not after.
This tariff is tied to specific, unresolved trade disputes. Treat the product lists, exclusions, and even the effective date as subject to change, and confirm current status with a customs broker or trade counsel before finalizing pricing on an exposed product line.
Why it matters: the businesses that get hurt worst by tariff changes are usually the ones that find out from a customs bill instead of from checking ahead of time.
09. How AtlanticWorks Helps
AtlanticWorks helps Atlantic Canada manufacturers, wholesalers, and DTC brands selling into the US update the Shopify and CRM side of a tariff shift like this: repricing exposed SKUs, configuring ERP-connected landed cost so duty changes flow through automatically, and flagging affected wholesale accounts in HubSpot so sales and support give a consistent answer. As a certified Shopify, HubSpot, Google, and Salesforce partner, we build this so you keep full ownership of the result. It starts with a free assessment of your current US pricing and margin exposure.
10. Key Takeaways
- Section 338 of the Tariff Act of 1930 lets the US impose duties up to 50 percent on a trading partner found to discriminate against US commerce, and it was used against Canada for the first time in nearly a century in July 2026.
- The tariff takes effect August 19, 2026, and covers motor vehicles, dairy, and alcohol, plus a wide secondary list including electronics, furniture, building materials, plastics, clothing, footwear, toys, machinery, cosmetics, and agricultural goods.
- CUSMA-compliant goods are not excluded from this tariff, which is a meaningful break from earlier US tariff actions on Canada that generally carved out CUSMA-originating products.
- Energy, potash, fish, critical minerals, qualifying aircraft parts, and goods already under Section 232 tariffs such as steel, aluminum, copper, and lumber are excluded from Section 338.
- Manufacturers and wholesalers should check actual HS codes against the published lists, reprice exposed SKUs before the effective date, and stop relying on CUSMA paperwork to offset this specific duty.
11. Frequently Asked Questions
What is the Section 338 tariff on Canadian goods?
Section 338 refers to a provision of the Tariff Act of 1930 that lets the US president impose duties up to 50 percent on a trading partner found to discriminate against US commerce. In July 2026, the White House used it against Canada for the first time in nearly a century, signing three proclamations covering motor vehicles, dairy, and alcoholic beverages, with the tariff taking effect on August 19, 2026.
Does CUSMA still protect my products from the new 50 percent tariff?
No, not for this specific tariff. Earlier US tariffs on Canada, imposed under a different legal authority, generally excluded goods that qualified as CUSMA-originating. The Section 338 tariff is different: it applies to covered goods regardless of CUSMA compliance. A certificate of origin still matters for other existing tariffs and for Mexico and US trade generally, but it does not shield a covered product from this 50 percent duty.
Which products are covered by the Section 338 tariff?
The published lists span motor vehicles and auto parts, dairy products, and alcoholic beverages, plus a wide secondary list that includes electronics and telecom equipment, furniture and home goods, building materials such as lumber, plywood, doors and cement, plastics and packaging, clothing, footwear and luggage, toys and sporting goods, machinery and manufacturing inputs, cosmetics and fragrances, and agricultural products including flowers, plants and seeds. Confirm your specific HS code against the current published list before assuming coverage either way.
What Canadian goods are excluded from the Section 338 tariff?
Energy products, potash, fish and seafood, critical minerals, civil aircraft and qualifying aircraft parts, and Canadian goods already subject to separate Section 232 tariffs, such as steel, aluminum, copper, certain derivative products, and lumber and forestry products, are excluded from Section 338. These carve-outs exist because those categories are already tariffed under other US authorities or are considered strategically important to keep flowing.
Why did the US impose this tariff on Canada?
The White House cited discriminatory treatment of US goods, pointing to Canadian provinces removing US alcohol from store shelves, Canada granting better dairy market access to the European Union than to the US, and a cap on US vehicle exports into Canada. The three proclamations map directly to those three disputes: alcohol, dairy, and motor vehicles.
What should a Canadian manufacturer or wholesaler selling to the US do now?
Check your actual HS codes against the current Section 338 product lists rather than assuming your category is or is not covered, recalculate landed cost and margin on any exposed SKU before the August 19 effective date, update Shopify pricing, product data, and wholesale quotes to reflect the new cost, and talk to a customs broker if a product sits in a gray area. Do not rely on a CUSMA certificate of origin to solve this particular tariff, and treat your US pricing as something to revisit again as the situation develops.
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Not sure which of your products are actually exposed?
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