Eleven days remain before Washington closes the border to Canadian dairy, packaged alcohol and large motorcycles. A duty-stacking reversal already in force pushes some combined rates to 75 per cent. What importers and exporters need to do now.
OTTAWA AND WASHINGTON, SEPTEMBER 18, 2026 | Peacock Tariff Consulting
The Canada-United States trade dispute crossed a threshold this month that has no modern precedent. On September 29, at 12:01 a.m. Eastern time, a set of Canadian-origin goods will become ineligible for importation into the United States altogether. Not dutiable at a punitive rate. Excluded.
The mechanism is Section 338 of the Tariff Act of 1930, a statute that has sat largely unused for the better part of a century. Its subsection (b) authorises the President to exclude articles from importation where a foreign country has “maintained or increased” discrimination against United States commerce following an initial proclamation under subsection (a). On September 8, the administration signed five proclamations invoking it.
Three of those proclamations impose the bans. Two modify the scope of existing 50 per cent duties and, critically for anyone costing Canadian steel or aluminum into the United States, reverse the original policy against stacking Section 338 duties on top of Section 232 duties. Those modifications took effect on September 15.
How the sequence got here
The escalation has moved in defined steps. On July 20, 2026, the administration issued Proclamations 11046, 11047 and 11048, imposing 50 per cent additional ad valorem duties on specified Canadian imports following formal findings of trade discrimination in alcoholic beverages, dairy and motor vehicles. Those duties were originally scheduled to take effect on August 19.
Canada committed to modifying the practices at issue, and Proclamation 11056 suspended the duties for three days, from August 19 to August 22. On August 21 Canada ceased negotiations. Prime Minister Mark Carney has said Ottawa suspended talks rather than accept terms that would undermine Canadian workers, businesses and strategic sectors. The suspension lapsed, and the 50 per cent duties took effect on August 22, covering roughly 28 billion dollars of Canadian goods, about five per cent of Canadian exports.
Ottawa answered on September 8 with counter-tariffs of 15, 25 and 50 per cent on more than 700 American product lines representing about 27.6 billion Canadian dollars in annual imports. Rates were set to mirror the American rate applied to the equivalent good. Targeted sectors include steel and aluminum, dairy, appliances, agricultural equipment, pulp and paper, plastics, and electronics. Goods already in transit to Canada on September 8 were exempted, and the government paired the measures with a support package of roughly 7.5 billion dollars covering enhanced Employment Insurance access and business lending programmes.
Washington signed the five Section 338 proclamations the same day.
What the bans actually cover
The alcoholic beverages ban is the broadest. Drawn from an annex to the proclamation, it reaches packaged beer, wine in sparkling, still and vermouth forms across multiple subheadings, spirits including whiskey, bourbon, rye, brandy, rum, gin, vodka, tequila, mezcal, liqueurs, cordials and bitters, other fermented beverages such as cider and sake, and undenatured ethyl alcohol for beverage purposes.
The packaging distinction is commercially significant. Where an annex subheading is marked “Packaged,” the ban reaches only product in bottles, cans, boxes, kegs or similar direct-to-consumption containers. Canadian alcohol shipped in bulk, for example tanker loads destined for American bottling or blending, falls outside the ban, though it remains subject to the 50 per cent Section 338 duty under Proclamation 11046. Subheadings without the packaged limitation apply to all imports classified there.
The administration cited Saskatchewan’s August 27 announcement of an additional 50 per cent levy on United States alcoholic beverages, effective September 8, as evidence of increased discrimination. That is a notable feature of the current dispute: a provincial measure was used to justify a federal-level American exclusion order.
The dairy ban responds to Canada’s maintenance of tariff-rate quota allocation practices that originally triggered Proclamation 11047. It covers whey protein concentrates, modified whey, fluid whey and dried whey; invert molasses, cane molasses and other molasses; and non-alcoholic beer under HTSUS 2202.91.00, an inclusion under a dairy proclamation that appears to rest on classification adjacency rather than product logic.
The motor vehicle ban is the narrowest. It covers only motorcycles, including mopeds, with engine displacement exceeding 800 cubic centimetres, under HTSUS 8711.50.00. It responds to Canada’s 25 per cent tariff on non-originating United States vehicles and its tariff-rate quota system for vehicles qualifying under the Canada-United States-Mexico Agreement.
The transitional window, and the snap-back
Each ban proclamation carries two provisions importers need to understand precisely.
The transitional rule provides that Canadian goods already imported but not yet entered for consumption, or withdrawn from warehouse for consumption, before September 29 remain subject to the 50 per cent duty rather than the ban. That creates a narrow clearance window. For distributors holding Canadian inventory in bonded warehouses, the difference between filing a consumption entry on September 28 and September 30 is the difference between a costly shipment and an unusable one.
The severability provision is the more strategically interesting. If a court invalidates an import ban in whole or in part as to a particular import, that import does not become duty-free. It reverts to the 50 per cent ad valorem duty under the underlying proclamation. The structure means a successful legal challenge yields tariff relief at best, never free entry. Counsel evaluating litigation should price the upside accordingly.
Duty stacking: the change already in force
The provision with the broadest commercial reach took effect three days ago and has received less attention than the bans.
The two Canadian Tariff Modification Proclamations, effective September 15, reverse the original non-stacking rule. Proclamations 11046, 11047 and 11048 had provided that Section 338 duties “shall not apply to articles subject to duties pursuant to section 232.” The modifications provide that Section 338 duties now apply “in addition to” Section 232 duties.
The arithmetic is unforgiving. Aluminum profiles, bars, rods, tubes and pipes newly added by the Modified Motor Vehicle Tariff Proclamation now face 25 per cent under Section 232 plus 50 per cent under Section 338, for 75 per cent in combined additional duties on top of the applicable most-favoured-nation rate. Iron and steel structural products including columns, beams and structures face the same combined exposure.
Any importer whose landed cost model was built on the assumption that Section 232 and Section 338 would not stack is now working from stale numbers on affected lines. For products at typical distribution margins, a 75 per cent additional duty is not a margin problem. It is a sourcing decision.
Scope changes in both directions
The modification proclamations also add and remove specific goods from the 50 per cent duty lists, and the additions extend well beyond the sectors named in the proclamation titles.
The Modified Alcohol Tariff Proclamation adds cheese products including cheddar, Swiss, Emmentaler, Gruyere, Romano, Reggiano, Parmesan, Provolone, blue-veined varieties, Roquefort, Edam, Gouda, sheep’s milk cheese and cheese substitutes; oxidized and dehydrated fats and oils; raw bovine and equine hides and leather goods; raw and tanned furskins including beaver, chinchilla, ermine, lynx, raccoon, sable, fox and wolf; and motorboats and outboard motorboats of certain sizes. It removes whiskies and liqueurs in containers exceeding four litres.
The Modified Motor Vehicle Tariff Proclamation adds a sprawling list: iron and steel structures, columns and beams; aluminum profiles, bars, rods, tubes and pipes; flexible tubing; hooks, eyes, eyelets, rivets, beads, spangles, buckles, clasps and crown corks; sign and name plates; welding electrodes, wire and rods; seats convertible into beds and seating in bamboo, rattan, wood, teak, bent-wood, plastic and rubber; seat parts; office, kitchen and other furniture; mattress supports and mattresses; electric table, desk, bedside and floor-standing lamps in brass, base metal and non-metal, in LED and non-LED forms; golf carts; motor vehicles for the transport of persons with engines of 1,000 cubic centimetres or less; outboard motorboats of 7.5 metres or more; cheese not made from cow’s milk; paper and paperboard for writing and printing; and fishing rod parts.
Removals include salt and pure sodium chloride, Portland cement, certain chemically pure sugars, toilet and facial tissue stock, bed sheets and similar articles of paper pulp, refined lead, switchgear assemblies, switchboards and certain fishing rod parts.
The practical instruction is blunt: classification review is not optional. A Canadian furniture manufacturer, lighting supplier or paper mill that had no Section 338 exposure in August may have acquired it on September 15 without any change to its own product or conduct.
CUSMA offers no shelter
The most consequential legal feature of the September 8 proclamations is what they omit. They make no provision for preferential treatment of goods originating under the Canada-United States-Mexico Agreement.
Section 338 is standalone statutory authority that predates the agreement by nearly a century, and the United States implementing legislation provides at 19 U.S.C. section 4512(a)(1) that no provision of the agreement inconsistent with United States law shall have effect. The result is that CUSMA qualification, historically the primary duty mitigation tool for Canadian goods entering the United States, provides no relief from either the Section 338 duties or the import bans.
That will unsettle a great many compliance programmes. Canadian exporters have invested years in origin documentation, supplier certification and regional value content calculation on the premise that CUSMA qualification protects market access. For affected product lines, that premise no longer holds.
The choice of instrument also raises questions the administration has not answered. The dairy ban arises from Canada’s allocation of its cheese tariff-rate quota under CUSMA, a matter squarely within the scope of the agreement’s Chapter 31 dispute settlement panels. The motor vehicle dispute concerns tariff treatment of vehicles under the same framework. By proceeding under Section 338 rather than Chapter 31, Washington has opted for unilateral action over the mechanism the three parties negotiated for exactly these disagreements.
Canada may respond with challenges under both CUSMA Chapter 31 and the World Trade Organization Dispute Settlement Understanding. Their viability will turn on whether Section 338 actions qualify as emergency measures exempt from trade-agreement disciplines, and on whether the agreement’s dispute resolution exclusivity provisions are self-executing. Neither question has a settled answer, and neither will be resolved before September 29.
The drawback question
The proclamations are silent on whether Section 338 duties qualify for drawback under 19 U.S.C. section 1313. That leaves open whether United States Customs and Border Protection will treat them as refundable.
Banned goods cannot generate drawback, because they cannot lawfully enter. But importers paying Section 338 duties on goods later re-exported should preserve complete documentation pending clarification. If CBP ultimately permits drawback, the recoverable amounts on 50 and 75 per cent duty rates will be substantial, and the claims will only be available to firms that maintained records contemporaneously.
Political resistance, and its limits
The tariffs are not uncontested in Washington. The House of Representatives passed a resolution challenging the Canada tariffs by 219 to 211 in February, with six Republicans voting in favour. The Senate has previously passed a resolution revoking the underlying national emergency designation by 51 to 48, with Republican Senators Susan Collins, Mitch McConnell, Rand Paul and Lisa Murkowski joining all Democrats.
Those votes are politically significant and operationally close to meaningless. Any such resolution reaching the President’s desk will be vetoed, and the votes to override do not exist. Senator Collins has continued to press for carve-outs for affected industries in Maine, and Republican candidates in border and agricultural districts have been visibly searching for a workable message as the counter-tariffs bite. None of that changes the September 29 date.
How Canadian industry is responding
Some of the more interesting adaptation is happening without government involvement.
In British Columbia, CanCorr co-founder Baha Naemi responded to rising cross-border duties by telephoning his direct competitors, an unusual step in a business he describes as cutthroat, to audit national manufacturing capacity. Coordinating across rival plants, raw material suppliers and trade associations, Canadian packagers established that domestic capacity could replace imported finished packaging.
“The answer was overwhelmingly ‘yes,’” Naemi told CTV News.
The underlying trade pattern explains the opportunity. Flat cardboard sheet escaped the latest American tariff lists because United States plants depend heavily on Canadian supply. Fully assembled cardboard boxes made in Canada, by contrast, face steep barriers. Canadian buyers have meanwhile imported large volumes of finished boxes from the United States. Collectively, Canadian plants can replace hundreds of millions of dollars of American-made boxes now carrying retaliatory duties, keeping the work domestic and insulating buyers from surcharges.
That is import substitution operating as intended, and it illustrates why the Bank of Canada concluded that the counter-tariffs would have a muted inflationary effect: Ottawa deliberately selected lines where domestic substitution was feasible.
Not every sector has that option. A Montreal manufacturer has publicly explored relocating production to the United States rather than absorb the duties, and Canada’s trade remedy system is meanwhile absorbing its own pressures. The Canada Border Services Agency initiated dumping and subsidy investigations on August 31 into truck and bus tires from China, following a complaint by the Canadian Retread Manufacturers Association and Michelin North America (Canada) Inc. The Canadian International Trade Tribunal will issue a preliminary injury decision by October 30 and the CBSA will make preliminary determinations by November 30, in a market estimated at roughly 1.2 billion dollars annually. Canada currently has 187 special import measures in force, which applied to about 3.3 billion dollars of imports in 2025 in industries employing 43,728 people.
Who is most exposed
The concentration of harm is uneven, and mapping it matters for anyone assessing counterparty risk.
Canadian distillers and brewers carry the sharpest exposure. The packaged alcohol ban removes their primary export market entirely from September 29, and the bulk carve-out is useful only to producers whose product can be shipped unpackaged for American bottling, which excludes most craft operations and every brand whose value rests on Canadian packaging and provenance. Whisky producers with aged inventory built against United States demand face the additional problem that the asset cannot simply be redirected: barrel stocks laid down years ago were laid down for a market that is closing.
Dairy processors exporting whey and related protein products face a narrower but still material hit. Whey is a co-product of cheese manufacturing, which means the export ban does not reduce production volume, it eliminates an outlet for something a plant will keep producing regardless. Storage, alternative markets or disposal all carry cost.
Motorcycle and recreational vehicle distributors face an inventory timing problem more than a structural one, given the narrow scope of the motor vehicle ban, but the September 29 deadline is absolute for units not yet entered.
The largest aggregate exposure, however, sits with the firms caught by the stacking reversal rather than the bans. Canadian fabricators shipping structural steel and aluminum extrusion into United States construction and manufacturing supply chains now face combined additional duties of 75 per cent on affected lines. Those are commodity products sold on thin margins into price-sensitive markets. At that duty level, the question is not how to price the tariff but whether the business line survives.
The precedent problem
Trade practitioners have spent the month reaching for historical comparisons and coming up short. Section 338 has essentially never been used in this manner in the modern era. Its revival, and specifically the move from subsection (a) duties to subsection (b) exclusion orders within seven weeks, establishes a template that is now available for use against any trading partner the administration determines has discriminated against United States commerce.
Two features of that template are worth noting for firms trading well beyond Canada. First, the statutory finding of discrimination is made by the executive, with limited procedural constraint and no requirement for an injury determination of the kind that governs antidumping and countervailing duty proceedings. Second, the explicit subordination of trade agreement obligations to the statute, resting on the implementing legislation’s own terms, means the protection a preferential agreement provides is contingent on the executive choosing to act under an authority the agreement governs.
For compliance and risk functions, the practical takeaway is that agreement-based duty planning now requires a scenario in which the agreement does not apply. That is an uncomfortable assumption to build into a sourcing model, and it is the assumption September has forced.
An eleven-day checklist
For firms with exposure, the near-term actions are specific.
Review classifications against the updated duty and ban annexes, not against the summaries. The added and removed lines are granular, and product descriptions in the annexes control.
Prioritise entries for consumption before September 29 for any goods covered by the ban proclamations, including inventory sitting in bonded warehouses.
Rebuild landed cost models for products now subject to stacked Section 232 and Section 338 duties, and determine whether continued Canadian sourcing remains viable on affected lines.
Evaluate whether bulk shipment is a lawful alternative for alcohol products where the ban is limited to packaged goods, recognising that the 50 per cent duty still applies.
Preserve documentation supporting potential drawback claims on re-exported goods.
On the Canadian side, importers facing counter-tariffs with no viable substitute supply should prepare remission requests. Ottawa has confirmed it will continue accepting applications for exemption or refund from businesses experiencing significant harm.
Review contracts for tariff allocation language. Agreements that are silent on who bears a duty increase, or that contemplate duties but not import prohibitions, will generate disputes once the bans take effect. Force majeure clauses drafted for supply disruption may or may not reach a lawful exclusion order, and the answer will depend on the wording.
The wider reading
The move from duties to exclusion orders changes the character of the dispute. A tariff, however punitive, preserves a price at which trade continues. A ban does not. It converts a commercial calculation into a binary, and it does so under an authority that the agreement governing North American trade cannot override.
For Canadian exporters in the affected categories, the planning horizon has collapsed. For everyone else, the September 15 stacking reversal is the warning: exposure can now arrive through a scope modification to a proclamation whose title has nothing to do with your product, with seven days of notice. The compliance function that reviews these annexes line by line, every time, is no longer a cost centre.