Harmonized Tariff Schedule (HTS) — a plain-English guide

The Harmonized Tariff Schedule of the United States is the master list of everything the country imports and what it costs to bring in. It is maintained by the US International Trade Commission and it is the legal reference CBP uses to assess duty. If you import anything, you are reading — or should be reading — the HTS. Here is how to actually navigate it without a customs degree.

How the schedule is organised

The HTS is built on the international Harmonized System, so it shares its top-level structure with every other country that uses HS. It runs from raw materials at the front to finished manufactured goods at the back, in a nested hierarchy:

• 22 sections group the schedule by broad category (e.g. Section XI = textiles and textile articles).
• 99 chapters (the first 2 digits) narrow it down (e.g. Chapter 61 = knitted apparel).
• Headings (4 digits) name a class of product (e.g. 6109 = T-shirts and singlets).
• Subheadings (6 digits) are the international HS level (e.g. 6109.10 = of cotton).
• The US statistical line (10 digits) is what CBP charges against (e.g. 6109.10.0060).

How to read a duty rate

Each 10-digit line shows a rate in one of a few shapes. An ad valorem rate is a percentage of the customs value (e.g. 16.5%). A specific rate is an amount per unit (e.g. $0.51/kg). A compound rate combines both. And "Free" means genuinely duty-free — a real finding, not a blank. Read the unit of quantity too, because specific rates are charged against it.

Column 1 vs Column 2

The rates page has two columns. Column 1 is for countries with normal trade relations (NTR / most-favored-nation) — almost every US trading partner. It has a "General" sub-column and a "Special" sub-column for preferential programs like free-trade agreements. Column 2 is the much higher rate reserved for a small set of countries that don't have NTR status. Most importers only ever read Column 1 General.

Chapter 99 — where the tariffs of the moment live

Here's the part that trips people up: the base rate in Chapters 1–97 is often not the whole story. Temporary and additional duties — Section 301 China tariffs, Section 232 steel and aluminum measures, reciprocal tariffs — live in Chapter 99 and cross-reference back to your product's normal heading. To get your true rate you have to check both your Chapters 1–97 line and any Chapter 99 provisions that apply to your origin.

How the HTS changes

• The WCO updates the underlying HS every five years or so (the last major revision realigned thousands of codes).
• The USITC issues revisions throughout the year as trade actions take effect.
• Chapter 99 measures come and go by presidential proclamation and USTR action.
• A code you used last year may have been split, merged or renumbered.

Where to read it

The authoritative, always-current version is the USITC's online HTS. It is free, searchable and legally definitive. PortRobin reads from the same schedule of record, adds a plain-English gloss and the applicable Chapter 99 measures, and never shows a rate it can't source back to it.