Section 232 vs Section 301 vs IEEPA: A Decoder for US Tariff Authorities

Three statutory authorities drove almost every active U.S. tariff action between 2018 and early 2026. Section 232 (Trade Expansion Act of 1962) sits with the Commerce Department and addresses national-security threats from imports. Section 301 (Trade Act of 1974) sits with USTR and responds to unfair foreign trade practices. IEEPA (International Emergency Economic Powers Act) sat with the President directly and required only an emergency declaration, until the Supreme Court held in Learning Resources, Inc. v. Trump on February 20, 2026, that IEEPA does not authorize tariffs at all. This decoder maps how each authority works, where they overlap on a single entry, and what changed in 2026.

How the Three Authorities Work

Section 232: Trade Expansion Act of 1962, 19 U.S.C. § 1862

• Trigger: Commerce finds that imports threaten to impair national security. The statute does not define "national security," giving the executive broad interpretive latitude.

• Procedural clock: Commerce has up to 270 days to deliver a report. The President then has 90 days to determine whether to act. If action is taken, implementation follows within 15 days and Congress is notified within 30 days.

• Duration: No expiration once imposed. No sunset and no statutory renewal.

• Current reach: Steel and aluminum at 25% since March 2018 (raised to 50% on steel on June 4, 2025); passenger vehicles and light trucks at 25% effective April 3, 2025 under Proclamation 10908; auto parts at 25% from May 3, 2025; medium and heavy-duty vehicles and parts at 25% from November 2025; buses at 10%; semiconductors at 25% from January 15, 2026 under HTSUS 9903.79.01; patented pharmaceuticals at 100% baseline from July 31, 2026. Active investigations in copper and robotics may add further sectors through 2026.

• Exclusion architecture: Proclamations 10895 and 10896 (February 2025) ended the product-specific exclusion process and replaced it with an Inclusion Process. U.S. manufacturers now request that new derivative articles be added to Section 232 coverage. There is no mechanism for new product-specific exclusion relief under the current framework.

Section 301: Trade Act of 1974, 19 U.S.C. § 2411

• Trigger: USTR finds an act, policy, or practice of a foreign government that violates a trade agreement, denies U.S. rights, or is unjustifiable, unreasonable, or discriminatory and burdens U.S. commerce.

• Procedural clock: Investigation typically runs 12 to 18 months and involves public hearings and (in WTO-agreement cases) formal dispute proceedings.

• Four-year review: Section 307(c) requires USTR to review any Section 301 action four years after it was taken. If no continuation request is filed during the 60-day pre-anniversary window, the action terminates automatically.

• Current reach: China Lists 1 through 4 cover most Chinese-origin goods. List 1 at 25% (July 2018, $34 billion in imports), List 2 at 25% (August 2018, $16 billion), List 3 at 25% (May 2019, $200 billion), and List 4A at 7.5% (February 2020, approximately $300 billion). The 2024 four-year review raised rates on strategic sectors: EVs to 100%, solar cells to 50%, semiconductors to 50%, ship-to-shore cranes to 25%, and lithium-ion batteries to 25%.

• Exclusion process: Requests are HTSUS-subheading-specific (not company-specific), so benefits flow to all importers of the covered subheading. As of November 2025, 178 product exclusions were extended through November 10, 2026.

IEEPA: 50 U.S.C. § 1701 et seq.

• Trigger: President declares an "unusual and extraordinary threat" with a foreign source.

• Procedural clock: None required. Tariffs took effect within days of executive orders.

• Two tracks in 2025: Fentanyl and migration tariffs imposed 25% on Canada and Mexico and 10% (later 20%) on China, citing trafficking and illegal migration. The reciprocal tariff regime under Executive Order 14257 (April 2, 2025) imposed a 10% baseline on imports from substantially all countries plus country-specific rates above 10%.

• SCOTUS ruling: The Supreme Court ended the IEEPA tariff program in a 6 to 3 decision on February 20, 2026. Chief Justice Roberts, joined by Justices Gorsuch, Barrett, Sotomayor, Kagan, and Jackson, held that IEEPA's authority to "regulate importation" does not extend to imposing taxes or duties, which are "very clearly a branch of the taxing power" reserved to Congress under Article I.

How the Authorities Compare and Stack on a Single Entry

Three-authority comparison

The trade-off is consistent across the table. Speed correlates inversely with durability: IEEPA was fastest and least durable. Section 232 is slowest and most durable.

Chapter 99 HTSUS series by authority

Five stacking rules governing interactions as of May 2026

1. Section 232 steel and aluminum derivatives are excluded from IEEPA reciprocal tariffs.

2. Section 232 automobile and auto parts goods are not subject to Section 232 steel and aluminum tariffs under Proclamation 10908 logic.

3. Section 301 stacks with Section 232. China-origin steel products subject to 232 also carry 301 duties, an outcome USTR explicitly intended to reduce circumvention.

4. IEEPA fentanyl tariffs on China stacked on Section 301 while operative.

5. IEEPA is now void following Learning Resources, with refunds processed through CBP's CAPE module inside ACE.

Pre-ruling vs post-ruling tariff stack: China-origin steel valve, HTS 8481.80.30xx

In early February 2026, the stack comprised:

• MFN rate: 3%

• Section 301 List 3: 25%

• Section 232 steel derivative: 50% (post-June 2025 rate)

• IEEPA fentanyl: 20%

• Total: approximately 98% (no IEEPA reciprocal layer, Section 232 carve-out applied)

Post-Learning Resources, the IEEPA fentanyl layer drops. The Section 122 surcharge of 15% attaches where applicable, and the practical stack settles closer to 78%, pending the July 24 Section 122 expiration. Each step is workable manually for a few SKUs and intractable across portfolios with thousands.

What Changed After the Supreme Court Ruling

CBP stopped collecting IEEPA duties on February 24, 2026. The administration immediately invoked Section 122 of the Trade Act of 1974 as a temporary stopgap, and the permanent tariff architecture reconverged around three tools.

Section 122 (temporary, expires approximately July 24, 2026)

• 15% across-the-board surcharge (statutory maximum), effective February 24, 2026

• Maximum duration: 150 days (approximately July 24, 2026 unless Congress extends)

• Must be nondiscriminatory: cannot replicate the country-specific structure of the former IEEPA reciprocal regime

• Does not stack on Section 232 auto goods

• Electronics carve-outs: ADP machines, semiconductor manufacturing equipment, semiconductor devices, integrated circuits, smartphones, networking apparatus, monitors, and solid-state storage

Section 232 (permanent and expanding)

• Steel and aluminum at 50%, automobiles at 25%, auto parts at 25%, MHDVs at 25%, buses at 10%, semiconductors at 25%, and patented pharmaceuticals at 100% beginning July 31, 2026

• Inclusion Process continues three times per year, with new derivative HTSUS subheadings added each round

• Active investigations in copper and robotics may expand coverage before year-end

Section 301 (continuing)

• China Lists 1 through 4 remain at 7.5% to 25%

• Strategic-sector increases (EVs at 100%, solar at 50%, semiconductors at 50%) remain in effect

• 178 extended exclusions run through November 10, 2026

• New 301 investigations on forced labor, structural excess capacity, and country-specific practices rolling out from March 2026

Refunds

• CBP opened the CAPE module inside ACE on approximately April 20, 2026 to process IEEPA refund claims

• The Court of International Trade ordered in Atmus Filtration, Inc. v. United States (Ct. Int'l Trade, March 4, 2026) that CBP reliquidate IEEPA-affected entries without those duties for all importers, not only named plaintiffs

• Entries between April 5, 2025 and February 24, 2026 are the eligible window

• Entries with AD/CVD complexity, drawback claims, open protests, or reconciliation flags fall outside CAPE Phase 1 and need alternative remedies

Manage Tariff Complexity and IEEPA Refunds with Gaia Dynamics

The post-IEEPA tariff landscape requires three distinct work streams running simultaneously: Section 232 coverage tracking as the Inclusion Process adds new derivative HTSUS subheadings, Section 301 exclusion monitoring against November 2026 expiry dates and new investigation outcomes, and IEEPA refund processing against the CAPE window before reliquidation deadlines close.

Gaia Dynamics provides workflow tools that combine HTS classification at the 10-digit level, real-time tariff calculation across stacked Section 232, 301, and Section 122 layers, and CAPE-ready entry audit to identify overpayments on IEEPA-affected entries between April 5, 2025 and February 24, 2026. Each workflow is manageable for a handful of SKUs and intractable at portfolio scale without purpose-built tooling.

Frequently Asked Questions

Does Section 122 stack on Section 232 or Section 301? 

Section 122 does not stack on Section 232 auto goods and excludes specified electronics (ADP machines, integrated circuits, smartphones, networking apparatus, and solid-state storage). Section 301 continues to stack on Section 232. Section 122 applies only to non-Section-232, non-excluded entries. 

Why was IEEPA struck down but Section 232 and Section 301 left untouched? 

Courts found IEEPA's authority to "regulate importation" does not authorize tariffs, a power reserved to Congress. The major questions doctrine also required clearer authorization for a broad tariff regime. Sections 232 and 301 remain valid because Congress expressly delegated tariff authority through detailed statutory frameworks. 

Does CBP's CAPE refund process apply to all IEEPA entries automatically? 

No. Importers or brokers must submit affected entry summaries through CAPE for recalculation. Although the Atmus Filtration order applies broadly, refunds are not automatic. Entries involving AD/CVD, drawback, or open protests are excluded from CAPE Phase 1. 

How do importers file for IEEPA refunds through the CAPE module? 

Submit a CSV of affected entry summary numbers through CAPE in ACE for entries between April 5, 2025, and February 24, 2026. CBP will reliquidate entries without the IEEPA duty layer. Certain unresolved entries require separate processing.

What is a Section 301 product exclusion, and who qualifies? 

Section 301 exclusions apply to HTSUS subheadings, not individual companies. All importers of a covered subheading benefit. USTR administers exclusions through a public process, with approvals generally lasting one year and subject to extension.