Most goods entering the United States are declared by a licensed customs broker acting for the importer. The role exists because the filing carries legal consequences the importer usually cannot manage alone.
The importer remains responsible
A broker files on the importer's behalf, but the legal duty to declare goods accurately and pay what is owed stays with the importer of record.
That responsibility includes reasonable care in classification, valuation and origin, and errors can produce penalties even where the importer relied on someone else's work.
Which is why the relationship is documented by a power of attorney, defining what the broker may do and creating a record of who authorized the filing.
Classification is where the judgment sits
Every imported item is assigned a tariff classification code, and that code determines the duty rate, the applicability of trade remedies and which agencies must review the shipment.
The classification system is hierarchical and full of distinctions that turn on material, function and degree of assembly, so similar-looking products can fall in different places.
Disputes over classification are common, and importers can seek a binding ruling in advance rather than discovering the disagreement after goods arrive.
Valuation is not simply the invoice
Duty is generally assessed on transaction value, but that figure may include additions the invoice does not show, such as certain assists, royalties or packing costs.
Related-party transactions receive closer attention, since a price between affiliates may not reflect what an unrelated buyer would have paid.
Getting valuation wrong understates duty, and because entries can be reviewed after the fact, the correction may arrive long after the goods were sold.
Other agencies ride along on the entry
Customs is the gatekeeper, but food, drugs, vehicles, electronics, plants and many other categories carry requirements from other federal agencies enforced at the border.
Those requirements are transmitted through the same electronic filing, so the broker is assembling one submission that satisfies several regulators simultaneously.
A missing certificate from any one of them holds the shipment, and the storage costs accrue while the paperwork is resolved.
Why the role has not been automated away
Much of the filing is electronic, and routine, repetitive product lines can be handled with stored classifications and templates.
The remaining work is exception handling: new products, changed rules, questions from officers, and situations where the correct answer is genuinely arguable.
Because the rules change and vary by product and origin, importers generally treat classification as a maintained decision rather than something settled once.