How the lists work

Five checks

1. 01

   Take the 8-digit

   HTSUS into the United States; Canadian tariff item into Canada. 4- and 6-digit headings are not enough.

2. 02

   Search the live list

   CBP PDF for U.S. inbound. Canada.ca table for Canada inbound. SEC 338 is a working copy of those files, dated 21–26 August 2026.

3. 03

   Check origin

   U.S. list = product of Canada. Canada list = U.S. goods under Canada’s marking rules, not merely “shipped from the U.S.”

4. 04

   Check stacking

   U.S. 50% sits on top of MFN and most other duties except where 9903.03.15 or 9903.03.16 say 0 extra. Canada generally replaces or raises the prior surtax on that line rather than adding a second one.

5. 05

   Re-check after 8 September

   Canada’s page and CBSA customs notices can still change. In-transit goods on 8 September are generally carved out.

U.S. Chapter 99 headings

Report the Chapter 99 heading with the ordinary Chapter 1–97 commodity code. The 50% applies to covered goods entered for consumption, or withdrawn from warehouse, on or after 12:01 a.m. ET on 22 August 2026. USMCA origin does not turn it off.

9903.03.12

Alcohol annex

Beer, wine, spirits, plus selected wood, paper and hockey sticks. 50% additional.

9903.03.13

Dairy annex

Milk powders, whey, casein, selected sugars, hops, nonalcoholic beer. 50% additional.

9903.03.14

Broad annex

The long list: plants, cement, chemicals, plastics, leather, plywood, paper, textiles, tools, some machinery, furniture, sporting goods. 50% additional.

9903.03.15

Section 232 carve-out

0% extra under Section 338 for specified steel, aluminum, copper, autos and parts, wood products, semiconductors and patented pharmaceuticals already under Section 232. Those still pay whatever other duties apply.

9903.03.16

Civil aircraft carve-out

0% extra for qualifying civil aircraft, engines, parts, subassemblies and ground flight simulators meeting General Note 6. Unmanned aircraft are out.

What the U.S. list excludes

Energy, potash, fish, critical minerals, and goods already under Section 232 (steel, aluminum, copper, many autos and parts, some lumber) take 0 extra under Section 338. Softwood lumber already under 232 is generally not stacked with this 50%. Qualifying civil aircraft are likewise 0 extra. None of that is a free ride on ordinary duty.

Canada’s matching surtax

Effective 12:01 a.m. on 8 September 2026. Rates are meant to match the corresponding U.S. rate on that product. Origin is marking-rules origin. Existing Canadian auto and some steel/aluminum surtaxes continue separately. After the 26 August revision the published table is about 648 lines (down from 874 after fish and seafood came off). SEC 338 loaded 629 tariff items from the Finance backgrounder table.