All merchandise coming into the United States must clear customs and is subject to a customs duty unless specifically exempted by law.
Clearance involves a number of steps, inspection, appraisement, classification and liquidation.
The US Customs Service does not require an importer to have a license or permit. Other agencies may require a permit, license, or other certification depending on what is being imported. Customs entry forms do ask for your importer number. This is either your IRS business registration number, or if your business is not registered with the IRS or you do not have a business, your social security number. The importer must declare the dutiable value of merchandise.