Reference

What each tariff authority is, how the schedule is put together, and what the recurring terms mean. These notes are descriptive: they state what the instruments say and what the schedule does, and they name the primary source for each. Rates for a particular classification and origin are on the country and product pages.

The authorities

Which statute imposed a duty, and what it reaches.

Section 232 tariffs Section 232 of the Trade Expansion Act of 1962 lets the President adjust imports found to threaten national security. What is in force, and at what rate.
Section 301 tariffs Section 301 of the Trade Act of 1974 lets USTR act against a foreign country’s unfair trade practices. The China lists, the 2026 forced-labor action, and how each is reported.
Section 338 tariffs Section 338 of the Tariff Act of 1930 permits additional duties on a country found to discriminate against United States commerce. The Canada action, and what it covers.
IEEPA tariffs and the 2026 ruling Tariffs imposed under the International Emergency Economic Powers Act, and the Supreme Court decision that held the statute does not authorize them.
The Section 122 balance-of-payments surcharge Section 122 of the Trade Act of 1974 permits a temporary import surcharge for balance-of-payments purposes, limited to 150 days. The 2026 surcharge and its expiry.

The schedule

How the tariff schedule is put together.

How HTS codes are structured The Harmonized Tariff Schedule runs from two-digit chapters to ten-digit statistical lines. What each level means and where duty is actually assessed.
The Column 1 General rate The Column 1 General rate is the ordinary duty for a classification, applying to any origin with normal trade relations. How it relates to Column 1 Special and Column 2.
Chapter 99 of the tariff schedule Chapter 99 carries temporary modifications to the tariff schedule, including every trade remedy. What its headings mean and why they are not all additive.

Arriving at a number

What the duty is computed from.

How US import duty is calculated Duty is the Column 1 rate for the classification plus every trade remedy in scope for the origin, each charged against the same customs value.
Customs value Customs value is the amount duty is charged against, normally the transaction value of the goods. What it includes and what it does not.
Country of origin Country of origin is where goods were made or last substantially transformed. It is not where they were shipped from, and it decides which tariffs apply.
Merchandise processing and harbor maintenance fees The merchandise processing fee and the harbor maintenance fee are charges on an entry rather than duties on goods. Rates, exemptions and the caps.

What changes it

Claims, grants, separate orders, and dates.

Trade agreement preferences A preference claim replaces the Column 1 rate where goods qualify. It does not remove a Section 232, Section 301 or antidumping duty.
Tariff exclusions An exclusion excuses particular goods from a duty they would otherwise carry. How Section 301 and Section 232 exclusions are published and administered.
Antidumping and countervailing duties Antidumping and countervailing duties are set per exporter, deposited at entry and finalized at liquidation. Why no rate is published here.
When a tariff change takes effect Tariff actions take effect for goods entered for consumption on or after a stated date. Why the entry date, not the shipping date, is what matters.

Terms

Defined as the documents use them.

Tariff glossary The terms that recur in United States tariff documents, defined: Column 1, Chapter 99, entered value, liquidation, substantial transformation and more.

Rates by product and origin

One page per pair that carries a duty.

Tariffs by product and country resolves each taxed product category against each country of origin and states the duty, the headings it is reported under and the instrument behind each layer. It covers the 18 categories tracked here against the 120 countries facing any action.