US Import Tariff Glossary: HTS, AD/CVD, Section 301, 232, and More

Import compliance has its own language. Federal Register notices, customs rulings, and trade regulations are dense with abbreviations and technical terms that can be opaque even to experienced importers. If you've ever stared at a CBP notice wondering what "Column 1 Special" means or how a "countervailing duty" differs from an "anti-dumping duty," this glossary is for you.

Every term below is explained in plain English with context for how it affects your import costs. Bookmark this page — it's designed to be a reference you come back to.

A

AD/CVD (Anti-Dumping / Countervailing Duties)

Additional duties imposed on imports to offset unfair trade practices. Anti-dumping duties apply when a foreign manufacturer sells goods in the US at less than their normal value (i.e., below the price in their home market or below production cost). Countervailing duties apply when a foreign government subsidizes the production or export of goods, giving their manufacturers an unfair cost advantage.

AD/CVD rates are product-specific and country-specific. They can be modest (5–15%) or extreme (200%+). The Department of Commerce investigates and sets the rates; the USITC determines whether the US industry is being harmed. Once an AD/CVD order is in place, it typically stays active for years and is reviewed annually.

Why it matters: AD/CVD duties stack on top of your base HTS duty rate. A product with a 4% base rate that gets hit with a 45% anti-dumping duty suddenly costs 49% in duties. These orders can appear with relatively little warning if your product category is under investigation.

Assessed Duty Rate

The final duty rate applied to your import entry after liquidation. This may differ from the estimated rate you paid at the time of entry if CBP makes adjustments during the liquidation process.

B

Binding Ruling

A written decision from CBP that officially classifies a product under a specific HTS code. Once issued, the ruling is legally binding — CBP cannot retroactively reclassify that product as long as the facts match the ruling. Importers request binding rulings when classification is ambiguous or when the financial stakes of misclassification are high.

Why it matters: A binding ruling is your best protection against retroactive duty assessments. If you import high-volume products where the classification could go either way, getting a ruling before you import is well worth the effort.

Bonded Warehouse

A CBP-supervised facility where imported goods can be stored for up to five years without paying duties. Duties are only assessed when the goods are withdrawn for consumption in the US. If the goods are re-exported, no US duties apply.

Why it matters: Bonded warehousing can be a strategic tool when tariff rates are in flux. If you expect a rate to decrease — for example, if an exclusion is pending — you can hold goods in bond until the lower rate takes effect.

C

CBP (Customs and Border Protection)

The federal agency responsible for enforcing customs laws, collecting duties, and regulating imports. CBP officers at ports of entry review entries, assess duties, and conduct examinations. CBP also issues classification rulings, enforces trade remedy orders (AD/CVD), and administers programs like ACE and the Trusted Trader programs.

Column 1 General Rate

The standard duty rate applied to imports from countries with Normal Trade Relations (NTR) status, which includes nearly all US trading partners and all WTO member nations. When people refer to "the duty rate" for an HTS code, they typically mean the Column 1 General rate.

Column 1 Special Rate

A reduced or zero duty rate available under free trade agreements or preference programs. To claim a special rate, the product must qualify under the specific program's rules of origin, and the importer must make the claim on the entry filing. Common programs include USMCA (for Mexico and Canada), CAFTA-DR, and GSP.

Column 2 Rate

The highest statutory duty rate, applied to imports from countries without Normal Trade Relations status. Currently applies to very few countries (Cuba, North Korea). Column 2 rates are typically 5 to 10 times higher than Column 1 rates and are rarely relevant for most importers.

Country of Origin

The country where a product was manufactured or underwent its last substantial transformation. Country of origin determines which duty column applies, whether trade preference programs are available, and whether additional duties (AD/CVD, Section 301) apply. Accurate origin determination is critical — declaring the wrong country of origin can result in significant penalties.

CROSS (Customs Rulings Online Search System)

CBP's searchable database of past classification rulings, accessible at rulings.cbp.gov. Contains thousands of decisions on how specific products should be classified under the HTS. An essential research tool when you're trying to determine the correct HTS code for a product.

Customs Broker

A licensed professional who files customs entries on behalf of importers. Brokers handle classification, documentation, duty payment, and communication with CBP. Using a licensed broker is required for most commercial import entries (with limited exceptions). Your broker is your front line for classification accuracy and compliance.

D

De Minimis Threshold

The value below which imported goods are exempt from duties and formal entry requirements. For the US, the de minimis threshold is currently $800 per shipment. Goods valued at $800 or less can generally enter duty-free under an informal entry.

Drawback

A refund of duties previously paid on imported goods that are subsequently exported, either in their original form or after being manufactured into a different product. Duty drawback can recover up to 99% of the duties paid. It requires detailed recordkeeping and a formal claim process, but for manufacturers who import materials and export finished goods, it can represent significant savings.

Duty Rate

The percentage (or per-unit amount) charged on imported goods. Duty rates in the HTS are expressed as:

• Ad valorem — a percentage of the product's customs value (e.g., 5.3%)
• Specific — a fixed amount per unit of quantity (e.g., 4.8¢/kg)
• Compound — a combination of both (e.g., 14.9¢/kg + 6.2%)

The applicable duty rate depends on the HTS classification, country of origin, and any additional trade actions in effect.

E

Entry

The formal process of declaring imported goods to CBP, providing required documentation, and paying estimated duties. Most commercial imports require a formal entry, which includes the entry summary (CBP Form 7501), commercial invoice, packing list, and bill of lading. The entry must be filed within 15 days of the goods arriving at the port.

Exclusion

An exemption from additional tariffs (typically Section 301 or Section 232) granted for specific products. Exclusions may be product-specific or granted to individual importers. They are typically temporary and must be renewed. When an exclusion is in effect, the additional tariff does not apply to the covered products.

Why it matters: Exclusions can save importers tens of thousands to millions of dollars. When new tariff actions are announced, check immediately whether an exclusion process is available for your products.

F

Federal Register

The official daily journal of the US government, published by the National Archives. All tariff-related changes — executive orders, trade action modifications, AD/CVD determinations, and HTS schedule adjustments — are published here. It is the authoritative source for tariff changes, but it publishes hundreds of documents daily, making manual monitoring impractical.

Why it matters: If a tariff change isn't in the Federal Register, it isn't official. Every rate change, exclusion, and trade action that affects your duties will appear here first. ImportSignal monitors the Federal Register nightly so you don't have to.

First Sale Rule

A valuation method that allows importers to use the price from an earlier sale in a multi-tiered transaction (e.g., the factory-to-middleman price rather than the middleman-to-importer price) as the customs value for duty calculation. When applicable, this can significantly reduce the dutiable value and therefore the duties owed.

Foreign Trade Zone (FTZ)

A designated area within the US that is considered outside the customs territory for duty purposes. Goods can be brought into an FTZ without paying duties, then stored, assembled, manufactured, or re-exported. Duties are only assessed when goods enter US commerce, and importers can often choose the most favorable HTS classification for the finished product.

G

General Rules of Interpretation (GRI)

The six rules in the HTS that govern how products are classified when the tariff headings and notes don't provide a clear answer. The GRI is applied sequentially — Rule 1 (the terms of the headings and section/chapter notes) takes precedence, and subsequent rules apply only when Rule 1 doesn't resolve the classification. Understanding GRI is essential for any non-straightforward classification.

GSP (Generalized System of Preferences)

A US trade preference program that provides duty-free treatment for eligible products from designated developing countries. GSP has been periodically renewed and allowed to lapse by Congress. When active, it can eliminate duties entirely on qualifying imports. Importers should verify the program's current status before relying on it.

H

Harmonized System (HS)

The international product classification standard maintained by the World Customs Organization (WCO). The HS provides a standardized six-digit coding system used by over 200 countries. The first six digits of every US HTS code are derived from the HS, ensuring international consistency. Countries then add additional digits for their own tariff and statistical purposes.

HTS (Harmonized Tariff Schedule)

The complete schedule of US import duty rates, maintained by the USITC and published at hts.usitc.gov. The HTS contains every product classification, duty rate, special program eligibility, and statistical reporting code. It is organized into 99 chapters grouped by product type. For a deeper explanation, see What Is an HTS Code?.

HTS Code

The 8-to-10-digit number assigned to every imported product that determines its duty rate. The first 6 digits follow the international HS standard; digits 7-8 set the US-specific duty rate; digits 9-10 are statistical suffixes. Getting the right HTS code is one of the most important decisions in import compliance because it directly determines your duty costs.

I

ISA (Importer Security Filing / "10+2")

A filing requirement that importers must submit to CBP at least 24 hours before goods are loaded onto a vessel bound for the US. The filing includes 10 data elements from the importer and 2 from the carrier. Failure to file can result in penalties and cargo holds.

L

Landed Cost

The total cost of getting an imported product from the supplier's facility to your warehouse, including product cost, freight, insurance, customs duties, fees, and handling charges. Duty rates are a major component of landed cost — and the component most likely to change without warning.

Liquidation

The final computation of duties owed on an import entry. When goods enter the US, you pay estimated duties. CBP then has up to one year (extendable to four years) to review the entry and finalize the duty amount through liquidation. If CBP determines you owe more, you receive a bill. If you overpaid, you receive a refund. Monitoring liquidation status is an important part of customs compliance.

M

Marking Requirements

CBP regulations requiring imported goods to be marked with their country of origin in a conspicuous place and in a manner that is legible, permanent, and in English. Failure to properly mark goods can result in a 10% marking duty on top of regular duties, or denial of entry.

MPF (Merchandise Processing Fee)

A fee assessed on most formal import entries, calculated as a percentage of the declared value of the goods. The current rate is 0.3464%, with a minimum of $31.67 and a maximum of $614.35 per entry. MPF applies in addition to any duty rates.

N

Normal Trade Relations (NTR)

Formerly called "Most Favored Nation" (MFN) status. A designation indicating that a country's imports receive the standard Column 1 General duty rates. Nearly all US trading partners have NTR status. Without it, imports are subject to the much higher Column 2 rates.

P

Prior Disclosure

A voluntary process by which an importer notifies CBP of a customs violation (such as misclassification or incorrect valuation) before CBP discovers it. Making a prior disclosure can significantly reduce the penalties that CBP would otherwise impose. If you discover a classification error that has been applied to multiple past entries, prior disclosure is typically the best path forward.

R

Reconciliation

A CBP program that allows importers to file entry summaries with estimated information and then submit final, corrected data later. This is useful when the correct value, classification, or origin isn't known at the time of entry — for example, when transfer pricing adjustments haven't been finalized.

Rules of Origin

The criteria used to determine the country of origin of a product for customs purposes. For trade preference programs (USMCA, GSP, etc.), products must meet specific rules — often requiring a certain percentage of value to be added in the qualifying country, or a "tariff shift" where the product's HTS classification changes as a result of manufacturing in that country.

S

Section 201 (Safeguard Tariffs)

A trade remedy that allows the President to impose temporary tariffs on specific products to protect a domestic industry from serious injury caused by increased imports. Section 201 tariffs are product-specific (not country-specific) and are intended to be temporary, with rates that decline over time. Recent examples include tariffs on solar panels and washing machines.

Section 232 (National Security Tariffs)

Tariffs imposed under the Trade Expansion Act of 1962 when the Department of Commerce determines that imports threaten national security. The most prominent Section 232 tariffs are 25% on steel and 10% on aluminum, which have been in effect since 2018 with various modifications and country exemptions.

Why it matters: Section 232 tariffs apply broadly across hundreds of HTS codes and affect importers regardless of country of origin (unless a specific exemption applies). If you import any steel or aluminum products, these tariffs are likely a significant cost factor.

Section 301 (Trade Act Tariffs)

Tariffs imposed by the US Trade Representative (USTR) in response to unfair trade practices by a foreign country. The most significant Section 301 tariffs are those on Chinese imports, which cover thousands of HTS codes at rates ranging from 7.5% to 100%. These tariffs have been modified multiple times since their initial imposition in 2018, with products added and removed from covered lists.

Why it matters: Section 301 tariffs are among the most impactful — and most frequently modified — trade actions affecting US importers. The covered product lists change through Federal Register notices, and rates have been increased in multiple rounds. Monitoring these changes is essential if you import from China.

Special Program Indicator (SPI)

A code on an import entry that claims eligibility for a reduced duty rate under a trade preference program. Common SPIs include "CA" (USMCA — Canada), "MX" (USMCA — Mexico), and "A" (GSP). Claiming the wrong SPI — or failing to claim one you're entitled to — directly affects your duty costs.

Staging

A provision in trade agreements where tariff reductions are phased in over several years rather than applied all at once. For example, a duty rate might decrease from 10% to 0% in five equal annual steps. The HTS schedule includes staging notes showing when each rate reduction takes effect.

Subheading

The six-digit level of the HTS classification (e.g., 6110.20). This is the most specific level that is internationally standardized under the Harmonized System. Countries add additional digits beyond the subheading for their own tariff and statistical purposes.

T

Tariff Engineering

The legal practice of modifying a product's design, material composition, or degree of assembly to achieve classification under an HTS code with a lower duty rate. For example, importing a product in an unassembled state might qualify it for a lower rate than the assembled version. Tariff engineering is legitimate when done properly, but requires careful analysis to ensure the modified product genuinely qualifies under the target classification.

Tariff-Rate Quota (TRQ)

A two-tiered tariff system where a lower duty rate applies to imports up to a specified quantity, and a higher rate applies to imports exceeding that quantity. TRQs are common for agricultural products. Once the quota is filled, subsequent imports pay the higher "over-quota" rate, which can be substantially more.

U

USMCA (United States-Mexico-Canada Agreement)

The trade agreement between the US, Mexico, and Canada (replacing NAFTA). Qualifying goods traded between the three countries can receive reduced or zero duty rates. Products must meet USMCA-specific rules of origin, which vary by product category and can be complex. Claiming USMCA benefits requires proper documentation and certification of origin.

USITC (US International Trade Commission)

The independent federal agency that maintains the official Harmonized Tariff Schedule, conducts trade remedy investigations (AD/CVD injury determinations, Section 201 cases), and publishes trade data. The USITC's HTS schedule at hts.usitc.gov is the authoritative source for current duty rates and classifications.

V

Valuation (Customs Value)

The value of imported goods used to calculate ad valorem duties. US customs valuation follows a hierarchy of methods, with transaction value (the price actually paid or payable) as the primary method. Proper valuation requires including certain costs (like royalties and assists) and excluding others (like international freight under certain circumstances). Incorrect valuation — whether intentional or accidental — is one of the most common compliance violations.

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Keeping Up With Tariff Changes

Understanding these terms is the foundation. But the tariff landscape changes constantly — new trade actions, modified rates, updated classifications. Knowing the vocabulary helps you understand what changed; monitoring those changes proactively helps you act before they hit your bottom line.

ImportSignal monitors the Federal Register and USITC schedule nightly and alerts you when changes affect your specific HTS codes. You can start monitoring within minutes by uploading your HTS catalog.

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Related Reading

• What Is an HTS Code? A Plain-English Guide — A deeper look at how HTS codes work, how they're structured, and how to find the right one.
• How to Track Tariff Changes on Your Imports — Why duty rates change and the best approaches for monitoring them.
• What Happens When Tariff Rates Change Mid-Shipment — How CBP determines which rate applies when duties change while your goods are in transit.
• US Tariff Rate Changes — March 2026 — A summary of notable tariff activity this month.