Customs duty.

In plain English

A customs duty is a tax charged on goods when they cross an international border, most often on the way into a country. Each country sets its own duties, so the same item can owe different amounts depending on where it is going. U.S. Customs and Border Protection describes customs duty as a tariff or tax imposed on goods transported across international borders, and says each article has its own duty rate, set by factors that include where it was acquired, where it was made, and what it is made of. Rates come from a classification system that, in CBP's words, provides duty rates for virtually every existing item. A duty is one charge among several: the same package can also owe a sales or value-added tax and separate import fees for processing it through customs.

01Why it matters

Anyone who buys from a seller abroad, or mails a gift overseas, can run into a duty. For goods coming into the United States, CBP says imported merchandise must clear customs and may be subject to duty whether it was bought from a business or from an individual. For a package going out, the destination country sets the duty, and the Postal Service's procedures in force since October 19, 2026 say the sender can be billed for it when the destination side seeks to collect from the sender and it has not been paid.

02The math, step by step

Say a country charges a 10 percent duty on a category of clothing. A jacket declared at $80 would owe $8 in duty at the border, before any sales tax or import fees the same country adds. If the declared value were wrong, the duty would be figured from the wrong number, which is why the value on the customs form matters.

Illustrative example. The amounts here are hypothetical, chosen to show how the math works, not real quoted rates or figures.

03What this is NOT

04Receipts

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