HTS Code Format Guide: How to Read a U.S. Tariff Number

Informational only — not legal advice.

1) How the digits break down

The U.S. tariff schedule — called the HTSUS (Harmonized Tariff Schedule of the United States) — is built on the international Harmonized System (HS). The first 6 digits are shared worldwide; the last 4 are U.S.-specific. (USITC About HTS)

(USITC FAQ — What do all the columns mean?)

Example: cotton t-shirts

Say you import men’s cotton t-shirts. The tariff number on your entry might read 6109.10.00.12. Here’s what each piece means:

• 6109 = the 4-digit heading (T-shirts, singlets, tank tops — knitted or crocheted)
• .10 = the 6-digit subheading (of cotton)
• .00 = the U.S. 8-digit legal rate line
• .12 = the statistical suffix (men’s or boys’)

The key practical point: 6109.10.00 is the legal duty line. 6109.10.00.12 is the reporting number your broker uses on the entry. Both refer to the same duty rate — the suffix just adds statistical detail. (USITC FAQ — What do all the columns mean?)

One more thing about reading the HTS: the schedule is a tree, not a flat list. Indentation matters — a row that isn’t indented is a heading, and deeper indentation means a narrower category underneath it. Child provisions can’t broaden what the parent heading covers. (USITC FAQ — What do all the columns mean?)

2) Why 8 digits matter more than 10 for duty

This is the rule most importers miss: the legal text ends at the 8-digit level. The 10-digit number is a statistical reporting number — it’s still important because your entry documents use it, but it doesn’t create a different duty rate from its 8-digit parent. (USITC About HTS, USITC FAQ — What do all the columns mean?)

What this means for your documents: If you’re reviewing a 7501 or an ACE data export, the tariff classification column shows the 10-digit number. But when you need to look up the duty rate, focus on the first 8 digits. Every 10-digit child under the same 8-digit parent inherits the same rate.

So when you’re reading a tariff number, ask two separate questions:

1. What is the 8-digit legal provision (the duty rule)?
2. What is the 10-digit reporting line (what’s actually on the entry)?

3) What the HTS columns tell you

When you look up a tariff number in the HTS (at hts.usitc.gov), you’ll see several columns. Here’s what they mean in plain English:

The three duty-rate columns work like this:

• Column 1-General — the standard rate for most imports (normal trade relations)
• Column 1-Special — lower or duty-free rates when a product qualifies under a trade agreement or preference program and the importer claims it
• Column 2 — rates for countries listed in HTS General Note 3(b)

For most importers reviewing their entries, the workflow is: find the correct 8-digit legal provision → look at the Column 1-General rate → then check whether a special program or Chapter 99 rule changes treatment. (USITC About HTS, USITC FAQ — What do all the columns mean?, USITC Definitions and Classifications)

4) Why your entry might show two tariff numbers

If you’re looking at a 7501 or ACE export and you see two tariff numbers for the same merchandise, that’s usually not a mistake. It means the shipment has:

• a base classification in Chapters 1–97 (the normal product classification), and
• an additional provision from Chapter 98 or Chapter 99

Chapter 98 covers special classification situations. Chapter 99 covers temporary legislation, temporary modifications, and additional import duties or restrictions. (USITC Definitions and Classifications, USITC About HTS)

What this looks like in practice

Back to those cotton t-shirts. Say you import them from a country subject to additional duties under an executive order. Your entry might show:

• 6109.10.00.12 — the base Chapter 1–97 classification (cotton t-shirts, men’s/boys’)
• 9903.88.15 — a Chapter 99 overlay that adds additional duties on top of the base rate

Both lines are correct. The Chapter 99 line doesn’t replace the base classification — it layers additional treatment on top of it. If you’re evaluating potential duty refunds or reviewing entry data, you need to account for both tariff numbers.

Sometimes there can be more than two tariff numbers on the same entry line. CBP’s ACE reporting rules allow more than one Chapter 99 number to appear with the same underlying Chapter 1-97 tariff number, including situations where multiple trade-remedy or quota provisions apply in a defined order. The base Chapter 1-97 classification still stays on the line and still carries the entered value.

5) The HTS by the numbers

Despite its size, the HTS is still a hierarchy — headings contain subheadings, which contain rate lines, which contain statistical suffixes. When you’re looking up a tariff number, start broad and work your way down.

USITC publishes the full schedule with search tools, tutorials, and downloadable data:

• Live search: hts.usitc.gov
• Tutorial: learning.usitc.gov/hts-guide
• Downloads: current revisions are available in JSON, CSV, XLSX, and PDF formats (USITC — 2026 HTS Revision 4)

6) Common mistakes (and what they look like)

Mistake 1: Treating the 10-digit number as a separate duty rule

What happens: You see 6109.10.00.12 on one entry and 6109.10.00.20 on another and think they might have different duty rates. They don’t — both are statistical children of the same 8-digit legal provision (6109.10.00), and they share the same rate. The extra two digits are for government reporting only. (USITC FAQ — What do all the columns mean?)

Mistake 2: Searching for a product name and assuming the first match is right

What happens: You search "cotton shirts" in the HTS and pick the first result. But the HTS uses precise legal language — "T-shirts, singlets, and other vests, knitted or crocheted" is not the same provision as "shirts, men’s or boys’, not knitted or crocheted." Keyword search alone is not enough; you need to read the section notes, the heading hierarchy, and sometimes CBP rulings to get the right classification. (USITC FAQ)

Mistake 3: Ignoring the Chapter 99 line on your entry

What happens: You focus on the base tariff number and miss the 9903.* line underneath it. That Chapter 99 line may be the provision that added extra duties to the shipment — and it’s often the line that matters most for evaluating refund eligibility.

Mistake 4: Mixing up HTS (imports) and Schedule B (exports)

What happens: A supplier gives you a "tariff code" from their export filing. The first 6 digits match between HTS and Schedule B, but the U.S. import and export systems diverge at the 8- and 10-digit levels. The number on your supplier’s export declaration may not match the number on your entry summary. (USITC Definitions and Classifications)

Mistake 5: Assuming a tariff number on an invoice is the same as the one on the entry

What happens: Your commercial invoice shows a tariff code, but the actual classification on the 7501 is different. The entry summary classification is what CBP uses for duty assessment — not the invoice. When reviewing duties, always work from the entry documents (7501 or ACE data), not the commercial invoice alone.

7) What to do now

If you’re reviewing import records:

• Identify the 8-digit parent provision for each tariff line.
• Keep the full 10-digit reporting number — you’ll need it for entry-level work.
• Check for any Chapter 99 overlay that may add or change duty treatment.
• Don’t assume a keyword match is enough — read the surrounding notes and legal text, or work with your broker or trade counsel.

If you already have 7501s or ACE exports, upload them. If not, start by requesting entry records from your broker or carrier.