An additional 50 percent ad valorem duty on specified Canadian HTS lines entered force at 12:01 a.m. Eastern on 22 August, 04:01 UTC [E1]. The clock sits in a White House proclamation that postponed three July Section 338 measures by three days [E1]. Those original proclamations, 11046, 11047 and 11048, used alleged Canadian discrimination on alcoholic beverages, dairy and motor vehicles as the predicate; the operative baskets are the annex lines assigned to 9903.03.12, 9903.03.13 and 9903.03.14 [E2][E3][E4]. A White House fact sheet describes the covered goods as ranging from wine to hockey sticks to cement, and excludes energy, potash, Section 232 goods and certain fish and critical-mineral lines [E5].
Mark Carney, in remarks on 22 August, said he had directed Canada’s negotiators to return to Ottawa and that Canada would match Washington’s new tariffs dollar for dollar [E6]. The measures, he said, would come into force the Tuesday after Labour Day [E6]. Labour Day 2026 is Monday 7 September, which makes that Tuesday 8 September [E7]. A 21 August PMO statement had already said that at midnight the United States intended to impose a 50 percent tariff on roughly $28 billion of Canadian goods [E8]. That $28 billion is a Canadian official characterisation. It is not an aggregate printed in the three U.S. proclamations, and the PMO sentence does not label the currency [E8][E2].
Carney named prospective Canadian target sectors: steel, dairy, appliances, agricultural equipment, pulp and paper, and electronics [E6]. He then said the details would be released in the coming days [E6]. Finance Canada’s public counter-tariff product list and tariff-response hub, checked on 22 August, still showed the pre-existing regime [E9][E10]. No 22 August Canada Gazette order, CBSA customs notice or Finance implementing instrument for the new matching tranche was retrieved [E9][E10]. Dollar-for-dollar is a political commitment. It is not yet an executable customs instruction, and it does not establish that every new Canadian line will itself be 50 percent [E6][E9].
CPKC and IBEW agreed on 21 August to binding arbitration that ends a signal-and-communications strike, with workers expected back on 24 August [E11]. Unifor announced a tentative agreement with General Motors on 22 August and mentioned tariff uncertainty in the bargaining climate [E12]. Neither document is the mechanism of Saturday’s rupture. The CPKC release does not cite Section 338. Unifor’s talks began on 10 August and follow the Ford pattern [E11][E12].
Midnight and 12:01 a.m. are not the same clock. Carney said midnight; the controlling U.S. text is 12:01 a.m. Eastern [E1][E8]. How much covered merchandise actually cleared after 04:01 UTC, and how Ottawa will define dollar-for-dollar when the schedule appears, are later ledgers [E1][E6]. Saturday’s record is the duty in force on the U.S. side and a dated Canadian promise without a product list [E1][E6][E9].