Customs declaration.

In plain English

A customs declaration is the information that travels with goods across a border so the receiving country's customs officials can decide what is allowed in and what is owed on it. For a package mailed from the United States, it is the customs form the sender completes, either online or at the Post Office counter. The Postal Service's guidance asks for the sender's and recipient's details, the total weight, a separate value for every item plus a total, and a specific description of each item that makes clear what it is, what it is made of, and what its purpose is. Those descriptions let the Postal Service assign Harmonized System codes, the 6-to-10-digit identifiers customs authorities worldwide use to screen incoming goods.

01Why it matters

The form is not a formality. The Postal Service says that if customs form requirements are not followed, officials in the receiving country may reject, return, or potentially even destroy the package. For goods coming into the United States, CBP warns that the description determines the classification number and duty rate assigned, so an inaccurate one can mean paying the wrong rate, and one inaccurate enough to look deliberately misleading can lead to the goods being seized and a fine.

02The math, step by step

A sender mailing a birthday present writes "electronics" on the form. That is too vague to identify the item, so the package risks delay or return. Writing "wireless headphones, plastic, for listening to audio" tells customs what the item is, what it is made of, and what it is for, and the value written next to it is what any duty is then figured from.

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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