Duties & Tariffs

A duty is the tax collected by a customs authority on imported (sometimes exported) goods. A tariff is the duty rate or schedule of rates a country applies. The amount you owe depends on the HS code, the country of origin, the customs value, and which trade programs apply. For most importers, duties and tariffs aren't one number — they're a stack, and the stack changes when policy changes.

How rates are expressed

A duty rate is expressed in one of two basic forms (or sometimes both):

• Ad valorem rate — a percentage of the imported good's customs value (for example, “5%”). Scales with the value of the shipment.
• Specific (per unit) rate — a fixed amount per physical unit (for example, “$0.15/kg”). Independent of declared value.

The base layer: MFN

MFN — Most Favored Nation — is the WTO principle that requires a country to extend the same baseline tariff treatment to every other WTO member. The MFN rate is the default tariff that applies absent a preferential agreement or a special program. For most products, MFN is the starting point that other programs adjust from.

The additional layers

On top of MFN, several categories of additional duty programs can apply:

• Section 232 — lets the U.S. President impose tariffs on imports that the Commerce Department finds to threaten national security. Section 232 has been used to impose additional duties on categories such as steel, aluminum, copper, and autos.
• Section 301 — gives the USTR authority to investigate and impose tariffs in response to foreign trade practices judged unfair or discriminatory. Section 301 underpins additional duties on Chinese imports.
• IEEPA tariffs — the International Emergency Economic Powers Act lets the U.S. President impose tariffs during declared national emergencies. IEEPA actions have been used for reciprocal-tariff programs and country-specific additional duties.
• Antidumping duty (ADD) — a tariff imposed on imports sold below their normal home-market value that are causing material injury to a domestic industry.
• Countervailing duty (CVD) — a duty that offsets subsidies granted to foreign producers by their government when those subsidies enable below-market export prices and injure the domestic industry.

Equivalents to these programs exist in other jurisdictions — the EU operates its own anti-dumping and anti-subsidy regimes, has its own emergency-tariff mechanisms, and runs the CBAM carbon-border-adjustment program against in-scope imports. The pattern (base rate plus additional programs) is general; the specific programs differ by importing country.

Stacking, exclusions, and quotas

When multiple programs apply to the same import, they stack: Section 232, Section 301, IEEPA reciprocal duties, and the base MFN rate can apply additively to a single shipment. The combined rate — sometimes called the layered or effective rate — is what drives the actual amount owed. Altana's duty calculations expose the stack so you can see which programs contributed how much.

A tariff exclusion is a published carve-out that removes a specific HS code, product, or country pairing from an additional-duty program. Exclusions are time-bound — they have a start date, an end date, and sometimes case-specific qualifying conditions. A tariff rate quota (TRQ) lets a defined volume of an import enter at a lower duty rate, with imports beyond that volume charged at a higher rate.

How you'll see this in Altana

• Duty workflows run against the catalog and a declared shipment. The result is a duty calculation broken down by program — MFN base, plus each applicable additional program — with the inputs that produced each line.
• Where Altana estimates duty — for a not-yet-entered shipment, for an entry being planned, for a tariff-program simulation — the estimate includes a confidence indicator and an explanation of the inputs.
• FTA qualification short-circuits parts of the stack — a qualifying product can move from MFN to a preferential rate, sometimes eliminating Section 232 or other program exposure.
• Tariff stacking calculations identify exclusions and TRQ allocations where they apply.

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