CAIN (Customs Assigned Importer Number)

A CAIN, or Customs Assigned Importer Number, is a unique identification number that U.S. Customs and Border Protection (CBP) assigns to importers who do not have an IRS Employer Identification Number (EIN) or Social Security Number (SSN) on file. It serves as the importer’s identifier in CBP’s systems and appears on all customs entry documents associated with that importer.

When a CAIN Is Used

Most U.S. businesses importing goods use their EIN (also called a Federal Tax ID) as their importer number. Individual importers who are not operating as a business can use their SSN. The CAIN comes into play when neither of those numbers is available or applicable. This occurs most commonly with foreign entities importing goods into the United States who do not have a U.S. tax identification number.

For example, a Canadian manufacturer shipping goods to a U.S. distributor might act as the importer of record under certain Incoterms arrangements (such as DDP, Delivered Duty Paid). The Canadian company does not have an EIN, so CBP assigns them a CAIN to track their import activity. The CAIN stays with that entity for all future imports and serves the same function as an EIN would for a domestic importer.

How to Obtain a CAIN

Importers do not apply for a CAIN directly. CBP assigns the number automatically when an importer files their first customs entry without an EIN or SSN. The customs broker handling the entry filing submits the necessary information (company name, address, contact details, country of incorporation), and CBP generates the CAIN through the Automated Commercial Environment (ACE) system.

The CAIN format typically consists of a code that identifies the entity type followed by a sequential number. Once assigned, the number does not change. The importer uses the same CAIN for every subsequent entry filing at any U.S. port. CBP maintains a database linking each CAIN to the entity’s identity information, import history, and compliance record.

CAIN vs. CBP Bond

Having a CAIN does not exempt an importer from other CBP requirements. Every importer (whether identified by EIN, SSN, or CAIN) must have a customs bond in place before goods can be entered. A single entry bond covers one specific shipment and costs roughly $50 to $150 depending on the entry value. A continuous bond covers all entries for a 12-month period and costs $300 to $600 annually for importers with normal risk profiles. The bond ensures CBP can collect duties, taxes, and fees if the importer fails to pay.

Implications for FBA Sellers

Most U.S.-based FBA sellers use their EIN as their importer number and never encounter a CAIN. The CAIN becomes relevant when a foreign seller ships inventory to Amazon’s U.S. fulfillment centers and acts as their own importer of record. A seller based in the United Kingdom importing goods into the U.S. for FBA fulfillment would receive a CAIN from CBP if they do not have a U.S. tax ID.

Foreign sellers should be aware that a CAIN establishes them as a known importer in CBP’s systems. This means their import history is tracked, and repeated compliance issues (late duty payments, classification errors, or marking violations) accumulate against their CAIN record. A poor compliance history can lead to increased examination rates on future shipments, which adds cost and delays.

Working with Customs Brokers

When engaging a customs broker for the first time, importers should provide either their EIN or confirm that they need a CAIN assigned. The broker needs this information before filing the first entry. Delays in obtaining the importer number hold up the entire clearance process, as no entry can be filed without one.

Importers who start with a CAIN and later obtain a U.S. EIN should update their customs records. The broker can link the new EIN to the existing importer account in ACE, ensuring continuity of import history. Failing to update the number can result in CBP treating the importer as two separate entities, which complicates compliance tracking and can cause issues during audits or focused assessments.

For importers routing shipments through a prep center like MeisterPrep, the importer number (whether EIN or CAIN) appears on the customs entry regardless of where the goods are delivered. The prep center’s address may be the delivery destination, but the importer of record and their identification number remain on the official customs documentation.