Trade Policy and Tariffs

Tariff Watch: September 2026 Monthly Recap

September brought escalating Section 338 actions involving Canada, new CBP automation requirements, additional Section 232 tariffs, and new tariff authority tied to Russian energy and sanctions evasion.

October 5, 2026
J.M. Rodgers Team
Reading Time: 7 minutes

Home » Tariff Watch: September 2026 Monthly Recap

The Month in One Minute

September 2026 was defined by two major themes: continued escalation in the U.S.-Canada trade dispute and an increased emphasis on electronic filing, supply-chain data, and automated validation by U.S. Customs and Border Protection (CBP).

On September 8, the White House announced five proclamations under Section 338 of the Tariff Act of 1930 that modified existing tariffs on certain Canadian products and established import prohibitions covering specified goods. The import bans took effect September 29, while changes to the products subject to Section 338 tariffs took effect September 15. The administration also confirmed that the Section 338 tariffs apply to covered goods regardless of USMCA origin status and in addition to applicable Section 232 tariffs.

Congress also passed, and President Donald Trump signed, the Lindsey O. Graham Sanctioning Russia and Iran Act of 2026. Among its provisions, the law establishes duties of up to 100% on goods from countries meeting specified criteria related to purchases of Russian-origin crude oil or natural gas or facilitation of Russian oil sanctions evasion.

Meanwhile, CBP implemented new Automated Commercial Environment (ACE) functionality for international mail and began issuing fatal errors when certain required copper smelt and cast information is omitted from covered entry summaries.

As October begins, additional developments involving CAPE Phase 3 and international mail compliance requirements are approaching.

What Changed This Month

September brought several notable developments affecting U.S. importers and the broader trade community:

The United States further escalated its Section 338 actions involving Canada. The September 8 proclamations modified the scope of existing 50% Section 338 tariffs and established import prohibitions on certain Canadian products. The actions affect specified products associated with the ongoing disputes involving alcoholic beverages, dairy, and motor vehicles. The import prohibitions took effect September 29.

CBP deployed the Entry Type 13 (ET13) test into the ACE production environment on September 22. ET13 creates a new electronic informal-entry process for eligible international mail shipments arriving through the U.S. Postal Service.

ACE began issuing fatal F794 errors for certain copper entries on September 14. Covered entry summaries are rejected when required primary country of smelt and country of cast information is not reported. CBP copper smelt and cast error-code update

President Trump signed the Lindsey O. Graham Sanctioning Russia and Iran Act of 2026 into law on September 18. Section 113 requires duties of up to 100% on goods from countries meeting specified statutory criteria involving Russian-origin crude oil or natural gas purchases or Russian oil sanctions evasion.

New Section 232 tariffs on certain unmanned aircraft systems and components took effect September 3. The proclamation imposes a 100% additional duty on specified UAS categories, docking stations, and critical components, and a 25% rate on other specified UAS. The proclamation also provides different treatment for certain countries and products.

A Closer Look at September’s Key Developments

Section 338 Moves From Additional Duties to Import Restrictions

One of September’s most significant trade developments was the continued escalation of Section 338 measures involving Canada.

Earlier Section 338 actions imposed additional 50% ad valorem duties on specified Canadian products. On September 8, the White House issued additional proclamations that both modified the products covered by those tariffs and established import prohibitions on certain Canadian products effective September 29.

The actions also clarified that Section 338 tariffs on covered merchandise apply regardless of whether the goods qualify as originating under the USMCA and apply in addition to tariffs imposed under Section 232. As a result, the tariff treatment of affected Canadian merchandise can vary depending on product classification and the trade measures applicable to the merchandise.

The move from additional duties to import prohibitions is particularly notable. For products covered by the September prohibitions, the issue is no longer simply the amount of additional duty assessed at entry. The specified merchandise is excluded from importation under the applicable proclamations.

CBP Expands the Role of Automated Validation

September also illustrated the growing role of automated data validation within ACE.

Effective September 14, ACE began rejecting entry summaries for specified copper articles when required primary country of smelt and country of cast information is omitted. CBP stated that ACE will return the F794 “ADDTNL DEC TYPE RQRD FOR ARTICLE” message as a fatal error when the required Type 12 record is not submitted for covered copper merchandise.

CBP followed that development with the September 22 implementation of the Entry Type 13 test in ACE. The test establishes a new electronic informal-entry process for eligible international mail shipments and represents another expansion of electronic customs processing within ACE.

CBP is also considering broader changes to the information collected about imported goods. Its September 2 advance notice of proposed rulemaking, Heightened Import Disclosures for Supply Chain Visibility, seeks public comment on possible requirements involving parties in the import supply chain, supply-chain tracing technologies, and foreign export documentation. The proposal remains under consideration and is not a final rule.

Taken together, these developments highlight the expanding role of structured supply-chain data and automated validation in U.S. customs processing.

Who Is Most Directly Affected

September’s developments have different implications depending on the products, countries, and entry processes involved.

Businesses trading with Canada: Importers of products covered by the September Section 338 actions may face additional tariff exposure or import prohibitions, depending on the applicable HTS classification and presidential action.
International mail participants: The September 22 ET13 deployment introduced a new electronic informal-entry process for qualifying international mail shipments.
Copper importers: Covered copper entry summaries are now subject to fatal ACE rejection when required primary country of smelt and country of cast information is omitted.
UAS and technology importers: New Section 232 tariffs took effect September 3 for specified unmanned aircraft systems, docking stations, and UAS components, with the applicable treatment depending on the product category and, in some cases, country of origin.
Importers involved in IEEPA refund litigation: CAPE Phase 3 is scheduled to address certain finally liquidated entries filed by plaintiffs for which the Court of International Trade has ordered reliquidation.

Why These Developments Matter

September’s developments illustrate how U.S. trade policy is increasingly being implemented through several mechanisms at the same time.

Tariff actions can overlap. A product may be affected by ordinary customs duties as well as additional duties imposed under authorities such as Sections 232 or 338. In the case of certain Canadian products, the September actions specifically provide for Section 338 duties to apply in addition to applicable Section 232 duties.

At the same time, customs administration is becoming increasingly dependent on specific electronic data elements. The copper F794 change provides a clear example: omission of required smelt and cast information now produces a fatal ACE rejection for covered entry summaries.

The Heightened Import Disclosures rulemaking points toward the same broader trend. CBP is considering whether additional information about supply-chain participants, foreign export records, and product tracing should become part of the import process. Because the rulemaking remains preliminary, any eventual requirements may differ from the concepts currently under consideration.

The Graham Act adds another dimension by connecting potential tariff exposure to geopolitical and sanctions-related criteria. Under Section 113, duties of up to 100% apply to goods from countries meeting the statutory criteria related to Russian energy purchases or Russian oil sanctions evasion. Those duties are in addition to other applicable duties, including duties imposed under Sections 122, 201, 232, and 301.

Together, these developments reflect a trade environment in which tariff policy, sanctions policy, customs data requirements, and automated enforcement systems are becoming increasingly interconnected.

Looking Ahead: Key Dates

Several upcoming dates relate directly to developments covered during September:

October 6: In a September 15 declaration filed with the U.S. Court of International Trade, CBP Trade Programs Executive Director Brandon Lord stated that CAPE Phase 3 is scheduled for deployment on October 6. Phase 3 covers finally liquidated entries filed by plaintiffs for which the CIT has ordered reliquidation. According to the declaration, plaintiffs who submitted a valid importer of record number to CBP by July 30 will be able to file CAPE declarations beginning October 6, with additional instructions expected for plaintiffs who submitted their information after that date.

October 22: The compliance date takes effect for specified provisions of CBP’s new postal informal-entry regulations. The rules affect certain international mail shipments subject to Partner Government Agency requirements, Chapter 98 or 99 treatment, and other specified duty provisions. ET13 provides an electronic informal-entry pathway for eligible mail shipments that do not qualify for the interim postal process.

December 1: Comments are due on CBP’s advance notice of proposed rulemaking regarding Heightened Import Disclosures for Supply Chain Visibility.

September’s developments highlight how quickly U.S. trade policy, customs enforcement, and import requirements can change. As new tariff actions, automated validations, and regulatory proposals continue to evolve, Tariff Watch will continue to track the developments shaping the import and supply-chain environment and provide clear context on what changes, when it takes effect, and who may be affected.

Sources

White House, September 8, 2026: “Fact Sheet: President Donald J. Trump Responds to Canada’s Retaliation”
White House, September 8, 2026: “Excluding Certain Canadian Products from Importation into the United States in Response to Continued Discrimination Against the Commerce of the United States With Respect to Motor Vehicles”
CBP / Federal Register, June 24, 2026: “Test of the New Electronic Informal Entry Process for Mail”
U.S. Customs and Border Protection, September 2026: “Entry Type 13 Implementation”
U.S. Customs and Border Protection, September 2026: “Copper Additional Smelt and Cast Country Detail Error Code Update”
U.S. Government Publishing Office, September 18, 2026: “Lindsey O. Graham Sanctioning Russia and Iran Act of 2026”
White House, August 13, 2026: “Adjusting Imports of Unmanned Aircraft Systems and Unmanned Aircraft Systems Components into the United States”
CBP / Federal Register, September 2, 2026: “Heightened Import Disclosures for Supply Chain Visibility”
CBP / Federal Register, June 24, 2026: “New Postal Informal Entry Process”
Husch Blackwell, September 16, 2026: “CBP States CAPE Phase 3 Will Deploy on October 6, 2026”