Canada Tariffs Become an Import Ban on Sept. 29

Five days from now, at 12:01 a.m. on September 29, the United States stops taxing a slice of Canadian imports and starts refusing them outright. Dairy products, alcoholic beverages, and motor vehicles — including all-terrain vehicles — convert from a 50% tariff to a flat ban on entry, under a 96-year-old statute that, until this summer, no president had ever actually used to impose a tariff.

If your business touches any of those three categories with Canada, this isn't a rate change to model into next quarter's landed costs. It's a line CBP won't let the goods cross at all.

Every tariff action this year has, underneath it, still been a tariff — a cost you could absorb, pass through, or work around with sourcing and classification. Section 338 of the Tariff Act of 1930 (19 U.S.C. § 1338) breaks that pattern. It lets the President respond to a trading partner's “discrimination” against U.S. commerce first with duties of up to 50%, and then, if the discrimination continues, with a straight exclusion from the U.S. market. There's no tariff engineering that fixes an exclusion — the goods simply aren't admissible.

For a distributor bringing in Canadian cheese, wine, or ATVs, or a DTC brand with a Canadian whisky component in a gift set, the operative question this week isn't “how much will this cost.” It's “can I even bring this in after September 29, and what do I do with the inventory already on the water.”

Section 338 is a genuine oddity among the tariff tools in rotation this year. Unlike Section 232 or Section 301, it doesn't require an investigation, a public comment period, or a hearing before the President acts — just a finding of discrimination and 30 days' notice (Morrison Foerster). Trade lawyers researching the statute's history found it “appears never before to have been used to impose tariffs” until this summer's proclamations, despite sitting on the books since 1930 (Morrison Foerster). That novelty cuts both ways: it gave the administration a fast-moving lever, and it leaves importers with essentially no case law to predict how far it can be pushed, or whether it holds up if challenged.

The proclamations name three specific grievances. On dairy, Proclamation 11047 (signed July 20) found that Canada lets retailers use its tariff-rate quota for European cheeses under its trade deal with the EU, but not for American cheese under USMCA — “Canada discriminates against U.S. goods that are similar to EU goods,” in the proclamation's own words (Federal Register). On autos, the trigger is Canada's own 25% retaliatory tariff on U.S.-made vehicles, first imposed in 2025. On alcohol, it's a set of Canadian provincial liquor boards that pulled American alcohol off their shelves that same year (Covington & Burling).

Canada didn't wait to see how far Washington would go. Its Department of Finance imposed dollar-for-dollar countermeasures on September 8, taxing $27.6 billion of U.S.-origin goods at rates that scale with the product (Department of Finance Canada). The split matters if you're shipping the other direction:

Ottawa paired the surtaxes with a C$7.5 billion support package for Canadian workers and businesses — including a C$1.5 billion fund for small and mid-sized exporters and expanded unemployment-insurance flexibility for laid-off workers (Department of Finance Canada) — a signal it's treating this as a prolonged fight, not a short one.

The administration has already floated Canadian autos and auto parts as the next target, with a January 1, 2027 start date under discussion — on top of, not instead of, what's happening this week (ArentFox Schiff). And because Section 338 has essentially no track record in court, don't be surprised if a legal challenge lands before the ink on the Federal Register notice is dry — a ruling either way would be the first real test of how far this authority reaches. We'll be watching the docket.

Got questions? Drop a comment below. Ask our licensed customs brokers, and they'll get right back to you here in the comments.