US HTS 2026 Revision 21: How Section 301 and 50% Section 232 Tariffs Stack on Industrial Imports

US Harmonized Tariff Schedule Revision 21, in force from 9 October 2026, did not change the basic rule that catches most importers out: special tariffs stack. A single steel or aluminium product from China can attract the ordinary MFN duty, a Section 301 duty and a Section 232 duty at the same time. This article explains how the layers combine and how to read them on an entry.

The three layers

1. **Column 1 general (MFN) duty:** the rate in the main HTS column for the 8 or 10 digit code.
2. **Section 301 (China only):** an additional duty from Chapter 99 headings 9903.88.xx and 9903.91.xx, set by the List the product falls in.
3. **Section 232 (steel, aluminium and derivatives):** an additional ad valorem duty of 50% on covered steel and aluminium content, from Chapter 99 headings 9903.80 to 9903.85.

Each layer is calculated on customs value (normally the transaction value, FOB basis for the US) and added together.

Section 301 Lists in brief

• **List 1 and List 2:** mainly industrial machinery, components and electronics, 25%.
• **List 3:** a broad range of intermediate and consumer goods, 25%.
• **List 4A:** consumer and industrial goods, 7.5%.
• **List 4B:** suspended, so the effective Section 301 rate is 0%.
• **2024 to 2026 increases:** specific goods such as EVs (100%), semiconductors and solar cells (50%), and EV batteries (25%) carry higher rates under 9903.91.

Always confirm the List from the Chapter 99 note matching your exact HTS code; descriptions alone are not enough. Exclusions are granted and expire on fixed dates.

Section 232 at 50%

Section 232 steel and aluminium duties rose to 50% in 2025. For derivative products, the duty applies to the value of the steel or aluminium content, which must be declared separately on the entry. The non-metal value of the product carries only the MFN duty and any Section 301 duty.

How they stack: worked example

A US importer brings in steel brackets from China, classified under an HTS line with 2.9% MFN duty, on Section 301 List 3 (25%), and fully covered by Section 232 steel (50%). Customs value: USD 100,000.

1. MFN duty: 100,000 x 2.9% = USD 2,900.
2. Section 301: 100,000 x 25% = USD 25,000.
3. Section 232: 100,000 x 50% = USD 50,000.
4. Total duty: USD 77,900, an effective 77.9% rate.

Then add the Merchandise Processing Fee and, for ocean shipments, the Harbor Maintenance Fee. Our US fees calculator shows the current FY2027 rates.

Second example: derivative with partial metal content

Aluminium-framed machinery from China, MFN 2.5%, Section 301 List 1 (25%), Section 232 derivative with aluminium content valued at USD 30,000 out of a USD 120,000 customs value.

1. MFN: 120,000 x 2.5% = USD 3,000.
2. Section 301: 120,000 x 25% = USD 30,000.
3. Section 232 on metal content only: 30,000 x 50% = USD 15,000.
4. Total: USD 48,000, an effective 40% rate.

What Revision 21 means for you

Each HTS revision can add, retire or renumber Chapter 99 lines. After any revision:

• Re-check the Chapter 99 lines on your recurring entries.
• Confirm any Section 301 exclusion has not expired.
• Re-verify whether a derivative product has been added to Section 232 coverage.

Use the US HTS lookup to confirm the current general rate, and read our Section 301 tariffs guide for the full List structure and recent increases.

Practical checklist

• Classify to 10 digits before working out stacking.
• Record country of origin, not country of export: Section 301 follows origin.
• Get the steel or aluminium content value from your supplier in writing.
• Budget duty on a landed-cost basis with the Landed Cost Calculator.

Rates in this article reflect the position on the publication date. US tariff actions change often, so confirm on the official HTS and Federal Register before you file.