How much customs will I pay?

Most people asking this question want a single number, and the honest answer is that half of it can be pinned down right away and half of it cannot without knowing the product's classification.

The part that can be pinned down: federal processing fees. On an informal entry, which covers most personal shipments, the Merchandise Processing Fee is a fixed $2.69, $8.06, or $12.09 depending on how the entry was processed — not a percentage. On a formal entry it is 0.3464% of the goods value, with a floor of $33.58 and a ceiling of $651.50. The Harbor Maintenance Fee is 0.125% but applies only to ocean vessel cargo, so if your parcel came by air or by post it is zero. Carrier charges are published too: couriers typically add either a flat fee or a percentage of the duty they advanced on your behalf, subject to a minimum.

The part that cannot be pinned down without more information: the duty itself. The rate attaches to a specific eight-digit subheading in the tariff schedule, and similar-looking products routinely sit in different subheadings with different rates. On top of the base rate, additional programs may apply depending on the product and its origin. Anyone giving you a confident single percentage without knowing your classification is guessing.

So the useful move is to establish what you can, then narrow the classification. If the shipment has already arrived and you have a bill, you can work backwards: separate the government lines from the carrier lines and check each against its published schedule.