US trade compliance glossary

10 core terms, each defined with the statute or regulation that gives it force — not a generic dictionary entry. Where a term maps to a live number, the entry links to the free tool that computes it rather than stating a figure that can go stale.

HTSUS (Harmonized Tariff Schedule of the United States) — The classification system that assigns every imported good a numeric code determining its duty treatment.
MFN Rate (Most Favored Nation / Column 1 General) — The general base duty rate the US applies to imports from normal-trade-relations countries.
Section 301 — US Trade Act authority for additional duties in response to unfair foreign trade practices.
Section 232 — National-security authority behind steel, aluminum, and copper tariffs and their derivative-article coverage.
AD/CVD (Antidumping and Countervailing Duty) — Producer-specific duties offsetting unfair pricing or a foreign government subsidy, set case by case.
USMCA Regional Value Content (RVC) — The originating-content threshold a good must meet to qualify for USMCA duty-free treatment.
Chapter 99 (HTSUS) — The tariff-schedule chapter where trade-remedy duties like Section 301 and 232 are actually implemented.
Entry Date Rule — Duty is set by the law in force on the date goods entered, not the date of the shipment, order, or lookup.
IEEPA (International Emergency Economic Powers Act) — The 1977 emergency-powers statute used for the 2025-2026 fentanyl and "reciprocal" tariffs, struck down by the Supreme Court.
Section 122 — Balance-of-payments authority for a temporary, broad-based import surcharge, used after IEEPA was struck down.

Looking for the duty on a specific entry rather than a definition? The free Tariff Calculator stacks MFN, Section 301, Section 232 and USMCA for your origin and entry date, with citations and a dated Entry Memo.

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