First-Time Importer Guide to U.S. Customs

If you are importing goods into the United States for the first time, U.S. Customs and Border Protection (CBP) treats you as the party legally responsible for getting the paperwork, classification, valuation, and duties right. That responsibility does not shift to your supplier, your freight forwarder, or your customs broker. Understanding that single fact up front prevents most first-timer problems.

This guide walks through what CBP actually requires: who the importer of record is, why you need an EIN and a customs bond, which documents move a shipment through clearance, how the HTS determines your duty rate, and the specific mistakes that most often trigger holds, exams, and penalties. It is written for importers clearing cargo through ports like San Diego and Otay Mesa, but the rules apply at every U.S. port of entry.

Who is the Importer of Record (and why it is you)

The importer of record (IOR) is the person or company CBP holds legally accountable for a shipment. The IOR is responsible for filing a correct entry, declaring an accurate value, classifying the goods under the right tariff number, paying all duties and fees, and keeping records for five years from the date of entry. If any of that is wrong, CBP looks to the IOR first, not the overseas seller.

To act as importer of record you must be able to demonstrate the right to make entry, typically as the owner, purchaser, or consignee of the goods. Foreign companies can serve as a non-resident importer of record, but they still need a U.S. bond and a way to satisfy CBP’s requirements. Many first-timers assume the shipping terms (such as who paid freight) decide who the IOR is. They do not. The IOR is a customs-law designation, and getting it wrong on the entry creates liability that is difficult to unwind later.

• The IOR files the entry, pays duties and fees, and is liable for accuracy.
• Recordkeeping obligation runs five years from the date of entry.
• Being the buyer under Incoterms does not automatically make you the IOR on the customs entry; the entry has to name the correct party.

Getting your EIN and importer number

Before you can file an entry, CBP needs a way to identify you in its systems. Most U.S. businesses use their IRS-issued Employer Identification Number (EIN) as their importer number. CBP appends a suffix to your EIN to form the importer of record number that appears on entries. A sole proprietor without an EIN can use a Social Security Number, and a foreign entity without an EIN can request a CBP-assigned number.

If this is your first entry, your customs broker will typically file a CBP Form 5106 to create or update your importer identity record with CBP. This establishes your name, address, and importer number in the ACE system. Setting this up correctly matters, because a mismatch between the name on your EIN, your bond, and your entry is a common reason a first shipment gets flagged.

The customs bond: single vs. continuous

A customs bond is a financial guarantee to CBP that you will pay all duties, taxes, and fees, and comply with customs regulations. It is not insurance for your cargo. It protects the government, not you. A bond is required for any formal entry (generally commercial goods valued over $2,500) and for shipments subject to other federal agency requirements regardless of value.

You choose between two types. A single transaction bond (STB) covers one shipment and is usually sized based on the value of the goods plus duties and fees. A continuous bond covers all of your entries at all U.S. ports for a twelve-month period and is typically written at a minimum of $50,000, or 10 percent of the duties, taxes, and fees you paid over the prior year, whichever is greater. The continuous bond uses activity code 1, the importer bond. If you plan to import more than a few times a year, a continuous bond is almost always cheaper and smoother than buying a single bond per shipment.

• Single transaction bond: one shipment, sized to value plus duties and fees.
• Continuous bond: all ports, twelve months, minimum $50,000 (activity code 1).
• A bond guarantees the government gets paid; it does not cover loss or damage to your goods.

The documents CBP and your broker need

Customs clearance runs on documentation. Missing or inconsistent paperwork is the most common cause of delay. For a standard commercial import, assemble these documents and make sure the details agree across every one of them.

Beyond the core set, goods regulated by a Partner Government Agency (PGA) such as the FDA, USDA, EPA, or FDA-regulated categories require additional filings and, in many cases, prior notice or registration. For ocean shipments, the Importer Security Filing (ISF, known as 10+2) must be transmitted to CBP at least 24 hours before the cargo is laded onto the vessel at the foreign port. A late, inaccurate, or missing ISF can draw a penalty of up to $5,000 per violation, so this is not a step to leave to the last minute.

• Commercial invoice: seller, buyer, detailed description, value, quantity, country of origin, terms of sale.
• Packing list: contents, weights, and dimensions per carton.
• Bill of lading (ocean) or air waybill (air): the transport contract and title document.
• Arrival notice from the carrier.
• Customs bond and any PGA-required permits, prior notices, or certificates.
• ISF (10+2) filed at least 24 hours before lading for ocean freight.

HTS classification and how duties are calculated

Every product imported into the United States is classified under the Harmonized Tariff Schedule of the United States (HTSUS), a ten-digit code that determines the duty rate, eligibility for trade programs, and which PGA rules apply. The first six digits are internationally harmonized; the last four are U.S.-specific. Classification is a legal determination based on the General Rules of Interpretation, not a guess from a product name. On the Mexican export side the equivalent concept is the fraccion arancelaria declared on the pedimento.

Your duty is generally calculated on the customs value of the goods, most often the transaction value, meaning the price actually paid or payable for the merchandise when sold for export to the United States. On top of duty, most formal entries carry a Merchandise Processing Fee (MPF) charged ad valorem within a set minimum and maximum, and ocean shipments also carry a Harbor Maintenance Fee (HMF). Some goods qualify for reduced or zero duty under trade agreements such as the USMCA, but only if they meet the rules of origin and you have valid supporting documentation. Getting the HTS wrong is not a small error. It changes your duty, can trigger back-duty demands and penalties, and can pull goods into or out of PGA jurisdiction.

• HTSUS is a ten-digit code; the correct one is a legal determination, not a label lookup.
• Duty is usually assessed on transaction value (price paid or payable for export to the U.S.).
• MPF applies to most formal entries; HMF applies to ocean cargo.
• USMCA and other preferential rates require meeting rules of origin plus documentation.

Formal vs. informal entry and the $800 de minimis line

CBP splits imports by value. Shipments valued at $2,500 or less generally clear as informal entries, which involve a simpler process and no bond in many cases. Shipments valued over $2,500, and certain regulated goods regardless of value, require a formal entry, which means a bond and a full entry filing through ACE. Knowing which track your shipment falls on tells you whether you need a bond before the goods arrive.

Separately, the de minimis provision under Section 321 allows most shipments with a retail value of $800 or less, imported by one person on one day, to enter free of duty and with minimal formality. De minimis is a useful tool for low-value ecommerce parcels, but it is not a workaround for splitting a larger commercial shipment to dodge duty, and it does not apply to goods that a PGA requires to be formally declared. Treat it as a genuine low-value allowance, not a loophole.