HTS Chapter 99: Section 301, 232 and Extra Duties

HTS Chapter 99 is where the United States writes its additional duties. Section 301 tariffs, Section 232 tariffs and other temporary measures all appear there as 9903 headings, and they can add more to the landed cost of a product than its regular duty rate. If you only read the rate next to your 10-digit code, you may be missing the larger part of the bill.

This guide is for importers, brokers and e-commerce sellers who need to know whether additional duties apply to their goods. It explains how Chapter 99 is organised, how its numbers are reported, how measures combine, and what changed in 2026. Everything here was checked against HTS 2026 Revision 20 and the Federal Register as of October 2026. Tariff measures change often, so treat every rate below as a snapshot and confirm it on your entry date.

Key takeaways

• Chapter 99 holds temporary legislation, trade-law modifications and additional restrictions. It exists only in the US schedule.
• Its numbers are reported in addition to the Chapter 1 to 97 code, never instead of it.
• Most current measures read "the duty provided in the applicable subheading +" a percentage, so they add to the regular rate.
• U.S. notes decide how measures combine and list exceptions by product, origin and date.
• In 2026, IEEPA duties ended after the Supreme Court ruling of 20 February, a 10% Section 122 surcharge ran from 24 February to 24 July, and new Section 301 country-wide duties took effect on 24 July.

How Chapter 99 is organised

The chapter title covers temporary legislation, temporary modifications established pursuant to trade legislation, and additional import restrictions under section 22 of the Agricultural Adjustment Act. Its U.S. note 1 explains that its provisions either temporarily amend provisions of chapters 1 to 98 or impose additional duties or restrictions under other legislation.

The chapter is split into subchapters. The ones importers meet most:

Almost every additional duty in the news sits in subchapter III, under 9903 headings.

How to report a Chapter 99 number

Chapter 99's statistical note 1 says to report the Chapter 99 number in addition to the 10-digit statistical reporting number from chapters 1 to 97 that would apply but for Chapter 99, with quantities in the units of chapters 1 to 97. In practice, an entry line for an affected product carries two or more numbers: the product code and each applicable 9903 heading.

A notice in Chapter 99 adds that these numbers apply only to imports and may not be reported on export declarations.

The main families of 9903 headings

As printed in Revision 20, a few ranges cover most consumer goods. USITC's FAQ notes that it publishes a reference table of China Section 301 coverage, but that the table is not part of the HTS and should not be relied on as an authoritative source; the U.S. notes are.

The last range is new in 2026. On 28 July 2026, the Federal Register published the US Trade Representative's notice of actions in 60 Section 301 investigations concerning forced labor import prohibitions (91 FR 47318). It set additional duties of 10% for economies that impose or have committed to a forced labor import prohibition, and 12.5% for others, with some rates net of the product's MFN duty, effective for goods entered from 12:01 a.m. eastern time on 24 July 2026. In Revision 20, heading 9903.05.84 covers products of Vietnam at the applicable duty plus 12.5%, and 9903.05.31 does the same for products of China.

How measures combine

There is no single stacking rule. Each U.S. note says how its heading interacts with others, and you have to read them together. Three patterns recur:

1. Cumulative. U.S. note 52(a) states that goods subject to headings 9903.05.20 to 9903.05.84 remain subject to the general rates of chapters 1 to 97 and to any other additional duty in subchapter III or IV, except as the note provides. It also states that goods eligible for special tariff treatment under general note 3(c)(i), such as free trade agreement rates, are still subject to these duties unless an exception applies.
2. Exclusive. Some headings switch a measure off for goods covered by another. Heading 9903.05.90, for example, exempts aluminum, steel and copper articles, passenger vehicles and listed vehicle parts from the note 52 duties.
3. Time-limited. Transit provisions such as 9903.05.85 spare goods loaded and in transit before a measure's start date, if entered before a stated deadline.

Antidumping and countervailing duties sit outside the HTS altogether. USITC notes they are not in the schedule, and note 52 confirms that products remain subject to them.

What changed in 2026

The past year reshaped Chapter 99. The sequence below is drawn from Federal Register documents.

• 20 February 2026. The Supreme Court decided Learning Resources, Inc. v. Trump, holding that the International Emergency Economic Powers Act (IEEPA) does not authorize the President to impose tariffs. Executive Order 14389 of the same day terminated the IEEPA additional duties. CBP's June 2026 de minimis rule records both.
• 24 February to 24 July 2026. A presidential proclamation under Section 122 of the Trade Act of 1974 imposed a temporary import surcharge of 10% ad valorem for 150 days, effective 24 February and continuing through 12:01 a.m. eastern daylight time on 24 July 2026 (91 FR 9339).
• 24 July 2026. The Section 301 country-wide duties described above took effect.

Section 301 duties on products of China and Section 232 duties on metals, vehicles and other goods continued throughout. For refunds of IEEPA duties paid before February, follow CBP's published process rather than any general rule of thumb.

Worked example: a cotton T-shirt from Vietnam

A men's knitted cotton T-shirt classifies in 6109.10.00.12, with a 16.5% general rate (see our HTS code for T-shirts guide). If it is a product of Vietnam entered in October 2026, Revision 20 points to heading 9903.05.84: the duty of the applicable subheading plus 12.5%. On the face of the schedule, that is 16.5% plus 12.5%, so 29% of the customs value before fees.

Before relying on that figure, check the exceptions in note 52, the transit rule in 9903.05.85, whether any other measure applies to the goods, and whether the revision has changed since. The same T-shirt of Guatemalan origin, for example, falls under a different heading (9903.05.40, plus 10%) with its own textile exceptions.

How to check Chapter 99 for your product

1. Classify the product first. Chapter 99 depends on the Chapter 1 to 97 code; see how to find HTS code numbers.
2. Read the footnotes on your line. Notes such as "See 9903.88.01" are not legal text, but they point to measures to check.
3. Search the 9903 headings by origin and by your code in the U.S. notes. Origin is a separate determination from classification; see country of origin vs HS code.
4. Read each relevant note for exclusions, exemptions and effective dates.
5. Record the HTS revision and the date you checked.

Getting the base code wrong also gets Chapter 99 wrong, which is one reason customs misclassification penalties can be large.

Estimating additional duties with HTS Pilot

HTS Pilot estimates duty and landed cost per candidate code, by origin and entry date, including MFN, free trade agreement and column 2 rates and Chapter 99 additional duties. It adds a Chapter 99 duty only where it certainly applies, shows Section 301 and 232 measures as "may apply" rather than adding them, and flags when candidate codes lead to different duties. AD/CVD duties, quotas and domestic taxes are not included. All figures are estimates and the proposed codes are suggestions for reference, not official classification decisions.

Summary

HTS Chapter 99 is where most of the 2026 tariff changes live. Classify the product first, then read every 9903 heading and U.S. note that could reach it, report each applicable number next to your code, and date your check. A rate that was right in June may be wrong in October.

Frequently asked questions

What is Chapter 99 of the HTS?

It is the US-only chapter for temporary legislation, temporary modifications established under trade laws and additional import restrictions. Its 9903 headings carry additional duties such as Section 301 and Section 232 measures. A Chapter 99 number is reported together with the product's regular Chapter 1 to 97 code, and the duties it sets apply on top of or in place of the regular rate.

Do Chapter 99 duties replace the normal duty rate?

Usually not. Most current 9903 headings say the duty is the duty provided in the applicable subheading plus an additional percentage, so the regular rate still applies and the extra duty is added. A few headings set a flat rate instead. Each heading and its U.S. note state which form applies, along with any exceptions.

Can several Chapter 99 duties apply to the same product?

Yes, and the U.S. notes decide how they combine. For example, U.S. note 52 to subchapter III says goods subject to the duties of headings 9903.05.20 to 9903.05.84 also remain subject to any other additional duty in that subchapter, except as the note provides. Other notes exclude goods already covered by another measure. Read the note for every heading that might apply.

Are IEEPA tariffs still collected in 2026?

No. CBP's June 2026 rule records that on 20 February 2026 the Supreme Court held in Learning Resources, Inc. v. Trump that IEEPA does not authorize tariffs, and that Executive Order 14389 terminated the IEEPA additional duties. Other measures, including Section 301 and Section 232 duties, were not affected by that decision and continue to apply where their terms reach.

Sources

The official texts and pages this article relies on. Check them for the current version before you act.

1. HTS Chapter 99, 2026 Revision 20 - USITC hts.usitc.gov
2. Notice of Actions in Section 301 Investigations related to forced labor import prohibitions, 91 FR 47318 - Federal Register federalregister.gov
3. Imposing a Temporary Import Surcharge, 91 FR 9339 - Federal Register federalregister.gov
4. CBP interim final rule on the de minimis suspension, background on Learning Resources v. Trump and E.O. 14389, 91 FR 37789 - Federal Register federalregister.gov
5. FAQs about tariff classification and the HTS - U.S. International Trade Commission usitc.gov

This article is general information, not legal advice and not a classification decision. Tariff texts, rates and rulings change: check the current official sources, and ask the customs authority for a binding ruling where the answer matters.