19 CFR 24.5 is the Customs and Border Protection regulation that requires every importer to obtain a filing identification number by submitting CBP Form 5106, the Create/Update Importer Identity Form, before the first formal customs entry or the first request for a CBP service that will produce a bill or refund.1eCFR. 19 CFR 24.5 – Filing Identification Number
When You Have to File
Under 19 CFR 24.5(a), any person, business, government agency, or other organization has to file Form 5106 with either its first formal customs entry or its first request for CBP services that will generate a bill or refund.1eCFR. 19 CFR 24.5 – Filing Identification Number If you have never imported and are bringing in a commercial shipment for the first time, the form comes first.
A separate Form 5106 is required for the ultimate consignee when that party differs from the importer of record. If a broker files an entry for a client, both the importer and the consignee receiving the goods need a Form 5106 on file. The form is available at any CBP office and on CBP’s website.2U.S. Customs and Border Protection. CBP Form 5106 – Create/Update Importer Identity Form
Which Number Goes on the Form
Section 24.5(b) sets a clear order. Your IRS Employer Identification Number goes first. If you do not have an EIN, use your Social Security number.1eCFR. 19 CFR 24.5 – Filing Identification Number Most companies already have an EIN, so for a typical corporate importer the choice is obvious. An individual importer without a business tax number uses an SSN.
If you have neither, the regulation tells you to write “None” on the lines provided for both numbers and file the form in duplicate.3Government Publishing Office. 19 CFR 24.5 – Filing Identification Number This is the situation for foreign companies and non-resident importers with no U.S. tax presence. The duplicate copy is what CBP uses to send an assigned number back to you.
If You Have No U.S. Tax ID
When Form 5106 arrives with no EIN and no SSN, the local CBP office assigns an importer identification number, informally called a Customs Assigned Importer Number, or CAIN.4U.S. Customs and Border Protection. Importer Numbers The officer writes the assigned number onto the form and returns the duplicate to the filer.1eCFR. 19 CFR 24.5 – Filing Identification Number
That number is then your permanent identifier for future customs transactions. One point that surprises many foreign filers: if you later obtain an EIN or SSN after receiving a CAIN, you do not need to file a new Form 5106 unless CBP specifically asks you to.1eCFR. 19 CFR 24.5 – Filing Identification Number The assigned number stays valid.
Optional Suffix Codes for Branches and Vessels
Section 24.5(d) offers a two-digit suffix that can be appended to your EIN. A company with multiple branch offices can use it to track which location originated a transaction, and a vessel owner can tie transactions to a specific ship.1eCFR. 19 CFR 24.5 – Filing Identification Number
Each branch or vessel that needs its own suffix requires a separate Form 5106 listing the suffix code with the name and address for that location. The suffix then appears on CBP Form 7501 or its electronic equivalent whenever a transaction ties back to that branch or vessel. Suffix codes can be numeric, alphabetic, or a mix, but the letters O, Z, and I cannot be used. Leave the suffix blocks blank if you do not need the feature, and CBP will assign “00” automatically.1eCFR. 19 CFR 24.5 – Filing Identification Number
How the Number Works With Your Customs Bond
The identification number under 19 CFR 24.5 and the customs bond under 19 CFR Part 113 are separate requirements, and you cannot file a formal entry without both. The bond, filed on CBP Form 301, guarantees payment of duties, taxes, and fees.5U.S. Customs and Border Protection. CBP Form 301 Customs Bond The number from Form 5106 is what links your bond, your entry summaries, and your compliance records into a single account.
For a new importer, the practical order is: get your EIN from the IRS (or recognize that you will need a CAIN), file Form 5106 to establish your identification number, and then file Form 301 to secure your bond. Without the identification number, CBP has nothing to attach the bond or your future entries to.
Updating Form 5106
CBP accepts Form 5106 electronically through the Automated Commercial Environment portal, which is the standard route for brokers and frequent filers. Paper filing at a local port office is still available, which tends to matter for first-time or infrequent filers without ACE access.
If your business name, address, or other identifying information changes after the initial filing, submit an updated form so CBP records stay current. The regulation does not require a new filing simply because you later obtain an EIN or SSN after receiving a CAIN, but changes to your corporate structure or contact details should be reported. CBP uses the information on file to attach every entry summary, duty payment, and compliance action to your account.