Numbers that start with 9903, such as 9903.88.01, show up on customs entries, in messages from US Customs and Border Protection (CBP) and in trade news. They are not product codes: each one is an additional duty, or an exception to one, written into Chapter 99 of the US tariff. Here is how to read them.
Chapter 99, the tariff's temporary part
Chapters 1 to 97 of the Harmonized Tariff Schedule sort products and give their base duty rates. Chapter 99 holds what is added to them, or taken away, for a time: heading 9902 holds temporary reductions of the duty on some products, and heading 9903 holds the additional duties imposed under US trade laws, such as Sections 301, 232, 201 and 338, with their exceptions. Each action adds, changes or ends 9903 headings, and the US International Trade Commission (USITC) writes them into the next edition of the tariff.
A 9903 number is not your product's code
Your goods always keep their own ten-digit code from Chapters 1 to 97. When an additional duty applies to them, the entry also reports its 9903 number on the same line, beside that code, as CBP's instructions for the measure require. Some 9903 numbers are reported to show that an exception applies, and then add nothing. On an entry summary (CBP Form 7501), a line can therefore carry several numbers: the product's code and one 9903 number for each measure that concerns it.
The three parts of a heading
Take 9903.88.01, the first list of the Section 301 duties on goods from China. Its text reads: "Except as provided in headings 9903.88.05, 9903.88.06, … , articles the product of China, as provided for in U.S. note 20(a) to this subchapter and as provided for in the subheadings enumerated in U.S. note 20(b)". Its rate, in the General column: "The duty provided in the applicable subheading plus 25%".
- The exceptions
- "Except as provided in headings …" names other 9903 headings that take precedence, often exclusions granted for particular products. Goods that fall under one of them do not owe this heading's duty.
- The scope
- Which goods it covers: here, products of China, within the limits that a U.S. note of the chapter sets. The heading itself rarely lists products: its notes do.
- The rate
- "The duty provided in the applicable subheading plus 25%" means the base duty of the product's own line, plus 25% of the value of the goods. A heading whose rate reads "The duty provided in the applicable subheading" or "No change" adds nothing: it marks goods spared from a measure.
The U.S. notes hold the lists
The notes at the start of each subchapter of Chapter 99 say what the headings mean. One subdivision of a note usually lists the product codes a heading covers, by their eight-digit subheadings or ten-digit lines; for 9903.88.01, it is U.S. note 20(b). Other subdivisions set conditions, such as the content of a metal, a date of shipment or a use, or describe in words the products an exclusion spares. A product can therefore be on a list and still be excluded by a description elsewhere in the notes.
Several headings can apply
A product can owe duties under more than one 9903 heading, for example a Section 301 duty for its origin and a Section 232 duty for its metal. The notes say how they combine: some add up, some replace another, some exclude goods that another measure already covers. Each heading also has its own dates. The text in the tariff shows the state of the edition you read, and an official action can change a heading days or weeks before the USITC writes the change into a new edition.
How to check whether a heading applies
- Read the heading's scope: the countries, and the U.S. note it points to.
- Find your code in the note's list: your eight-digit subheading, or your full ten-digit line when the list goes that far.
- Read its exceptions, and the headings and notes they point to: an exclusion may describe your product.
- Check the dates: when the heading took effect and whether it has changed since, in the official notices as well as in the tariff.
On TariffTrust, every 9903 heading has its own page, such as 9903.88.01: its official text and rate, the subdivisions of the notes it cites with each code linked, and its history in the tariff. Each product line's page lists the headings whose text cites it. The trade updates say what each new action changes. And the calculator applies every heading at once for a product, a country of origin and a date of entry, combined as their notes say.
Updated October 30, 2026. General information as of that date, not legal or customs advice: the official texts prevail, and a licensed customs broker can confirm what applies to your goods.