HTS Chapter 99 Explained: Why Your Product Has Two Codes

Key Points

• Every imported product has a permanent classification in HTS Chapters 1 through 97; Chapter 99 codes are temporary overlays that impose additional duties on top of that base rate.
• When a Chapter 99 code applies, CBP requires both codes on the entry summary: the underlying Chapter 1-97 number and the Chapter 99 number.
• Additional duties under Chapter 99 are cumulative, meaning a single product can owe its normal column 1 rate plus a Section 232 duty plus a Section 301 duty at the same time.
• Chapter 99 also houses exclusions: a matching exclusion code can reduce or eliminate an additional duty, but only for the precise HTS scope and time window stated in the exclusion.
• Chapter 99 provisions are created by presidential proclamation or Federal Register notice and can change without altering the underlying classification in Chapters 1-97.

On this page

1. What Chapter 99 is and how it fits into the HTSUS structure
2. How the two-code system works on an entry
3. How duties stack: reading the full landed duty rate
4. Exclusions and offsets housed in Chapter 99
5. Common Chapter 99 trade remedy programs
6. What importers should do
7. Key references

Chapter 99 of the Harmonized Tariff Schedule of the United States (HTSUS) is a special-purpose chapter that holds temporary, government-imposed measures, primarily trade remedy tariffs and their exclusions. When a Chapter 99 code applies to your shipment, you must report it alongside your normal product classification. The result is that your entry carries two HTS codes and, almost always, a higher total duty rate than the base schedule alone would produce.

The links in this article go to the primary documents: the proclamations, Federal Register notices, and the official tariff schedule pages themselves. Read the source.

What Chapter 99 is and how it fits into the HTSUS structure

The Harmonized Tariff Schedule of the United States is organized into chapters numbered 1 through 99. Chapters 1 through 97 follow the international Harmonized System maintained by the World Customs Organization. Those chapters assign every physical good a permanent, six-digit-rooted classification based on what the product is.

Chapter 98 covers special classification provisions for returning U.S. goods and similar categories. Chapter 99 is different in kind: it is a domestic-only chapter reserved for measures that are temporary in nature and sit outside the permanent product-description framework. Congress and the executive branch use Chapter 99 as the vehicle for:

• Additional tariffs imposed under trade remedy statutes such as Section 232 of the Trade Expansion Act and Section 301 of the Trade Act of 1974.
• Safeguard measures under Section 201 of the Trade Act of 1974.
• Product exclusions that relieve specific importers or product descriptions from those additional duties.
• Quota and tariff-rate quota (TRQ) provisions tied to specific trade actions.

Because these measures are created by presidential proclamation or Federal Register notice, and because they expire or change based on policy decisions rather than product reclassification, they live in Chapter 99 rather than being embedded in the permanent chapter structure. For a broader comparison of the statutory authority behind each remedy type, see our guide on Section 232 vs. 301 vs. 201: Three Trade Remedy Tools Compared.

How the two-code system works on an entry

When you import a product subject to a Chapter 99 measure, U.S. Customs and Border Protection (CBP) requires you to report two separate HTS numbers on the entry summary (CBP Form 7501) and in your Automated Commercial Environment (ACE) filing:

1. The base classification, a 10-digit number from Chapters 1-97, which describes what the product is and carries the normal column 1 general rate of duty (or column 2, or free, as applicable).
2. The Chapter 99 overlay code, which triggers the additional duty and identifies the specific trade measure that applies.

The Chapter 99 code does not replace the underlying classification. It is additive. CBP systems calculate duty on each line: the base rate applies to the Chapter 1-97 code, and the additional rate applies to the Chapter 99 code. Both amounts are assessed on the same entered value.

Finding the right Chapter 99 code

Chapter 99 is organized by subheading ranges, each tied to a specific measure. The notes at the beginning of Chapter 99 in the official HTSUS describe which products are covered by each subheading and reference the underlying proclamation or notice. When you look up a product, you must cross-reference the Chapter 99 note language against your Chapter 1-97 classification to confirm coverage. The product description, the country of origin, and the date of importation all determine whether a given Chapter 99 subheading applies. A code that covers a product from one country may not cover the same product from another.

How duties stack: reading the full landed duty rate

Duty stacking is the practical consequence of the two-code system. To calculate the total additional duty owed at entry, add together every applicable rate:

• Normal trade relations (NTR) rate from the Chapter 1-97 classification (column 1, general).
• Section 232 additional duty, if the product is covered steel, aluminum, or another commodity subject to a Section 232 proclamation.
• Section 301 additional duty, if the product is on a covered list and originates in a designated country.
• Section 201 safeguard duty, if a safeguard tariff-rate quota applies and the in-quota volume has been exceeded.
• Antidumping (AD) or countervailing (CVD) duties, which are assessed separately but compound the landed cost further.

A practical example: a steel product from a covered country could owe the column 1 general rate, a Section 232 additional duty, and a Section 301 additional duty simultaneously. Each Chapter 99 subheading that applies generates its own duty line on the entry. There is no automatic cap or offset between separate Chapter 99 measures unless the specific note language says otherwise.

Entered value is the common base

All ad valorem additional duties in Chapter 99 are calculated on the same entered value as the base duty: the customs value of the merchandise determined under the relevant valuation rules. This means a higher customs value multiplies the impact of every stacked rate.

Exclusions and offsets housed in Chapter 99

Chapter 99 is also where product-specific exclusions live. When the relevant agency grants an exclusion from a Section 232 or Section 301 additional duty, it is published in the Federal Register and implemented through a dedicated Chapter 99 subheading. The exclusion subheading describes the product scope precisely, often at a level of specificity narrower than a 10-digit HTS number.

To claim an exclusion, the importer reports the exclusion subheading on the entry in addition to the base classification. The exclusion code essentially cancels the additional duty for qualifying merchandise. Key limitations:

• Exclusions are time-limited. The Federal Register notice states the effective dates, and the exclusion expires unless extended by a subsequent notice.
• Exclusions are product-specific, not importer-specific in most programs (though some programs have operated on a requester-specific basis).
• If an exclusion has expired and you did not claim it in time, you may be able to recover duties through a protest or refund claim. See our guide on the Tariff Exclusion Process: How Requests, Grants, and Refunds Work.

Common Chapter 99 trade remedy programs

The following are among the most frequently encountered Chapter 99 measure categories. The specific subheadings and rates for each are defined in the HTSUS notes and the underlying Federal Register notices.

Section 232 measures on steel and aluminum

Presidential proclamations issued under Section 232 of the Trade Expansion Act imposed additional duties on imports of steel mill products and aluminum products. The Chapter 99 subheadings covering these commodities specify which HTS Chapter 1-97 numbers are within scope. Country-specific exemptions, quota arrangements, and product exclusions are each implemented through distinct Chapter 99 subheadings. For a specific example of how Section 232 reaches beyond raw metals, see Section 232 Duties on Drones and UAS Components: CBP Guidance.

Section 301 measures

Section 301 of the Trade Act of 1974 authorizes additional duties in response to unfair trade practices. The Chapter 99 subheadings for Section 301 lists are organized by covered country and product list. Rates vary by list and have been modified by subsequent Federal Register notices. Country-specific forced labor measures have their own dedicated subheadings. Examples include the measures covered in our articles on EU Section 301 Forced Labor and Honduras Section 301 Forced Labor, each with its own Chapter 99 number and rate.

Section 201 safeguards

Global safeguard measures under Section 201 of the Trade Act of 1974 have been applied to products such as solar cells and washing machines. These measures use Chapter 99 to implement both the above-quota additional duty rates and the TRQ structure that allows a set volume of imports at a lower rate.

What importers should do

• Always look up Chapter 99 after you classify in Chapters 1-97. Classification is not complete until you have checked the Chapter 99 notes in the official HTSUS for every applicable measure, country of origin, and date of entry.
• Calculate the full stacked duty rate before sourcing decisions are made. Compare the column 1 general rate plus all applicable Chapter 99 rates to understand true landed cost; a low base tariff product can carry a substantial total duty burden once trade remedies are added.
• Monitor exclusion expiration dates. If you are relying on a Chapter 99 exclusion subheading to reduce your duty liability, track the expiration date in the Federal Register notice and file timely protests or refund claims if duties were assessed after an exclusion was in effect.
• Verify country-of-origin documentation supports your Chapter 99 position. Many Chapter 99 measures are country-specific; a mismatch between the declared origin and the actual origin creates both duty underpayment exposure and potential penalty risk.

Key references

• Harmonized Tariff Schedule of the United States (USITC): the authoritative, continuously updated HTSUS including Chapter 99 notes and subheadings.
• Federal Register (federalregister.gov): source for all proclamations and notices implementing Chapter 99 measures, exclusions, and extensions.
• White House Presidential Actions: Section 232 and Section 201 proclamations originate here.
• CBP Entry Summary guidance (cbp.gov): CBP instructions for reporting multiple HTS codes on entry summaries and in ACE.
• 19 U.S.C. 2411 (Section 301), Cornell LII: the statutory authority for Section 301 trade actions whose Chapter 99 codes appear throughout the tariff schedule.
• 19 U.S.C. 1862 (Section 232), Cornell LII: the statutory authority for national-security tariff actions implemented through Chapter 99.