Alien Registration Number (A-Number): What It Is and Where to Find It

You are staring at a form field right now. Maybe it is Form I-9 for a new job, a green card renewal on Form I-90, an N-400 naturalization application, or a FAFSA form for a child starting college.

The field asks for your Alien Registration Number, and you are not sure whether the number in your wallet or your inbox is the right one.

That confusion is common, and it is not because the concept is complicated. At least four different government-issued numbers show up on similar-looking documents, and nothing on the page tells you which is which.

This guide helps you to identify your A-Number on your most common documents: a green card, an EAD, a USCIS notice, an immigrant visa, or an I-94. It also covers the forms that ask for it, so you enter the right number the first time.

What Is an Alien Registration Number?

An Alien Registration Number, or A-Number, is a unique 7-9 digits identifier that the Department of Homeland Security assigns to a noncitizen. It always carries the letter "A" in front of it.

USCIS, Immigration and Customs Enforcement, and Customs and Border Protection all use it to pull up the same immigration file, regardless of which agency you are dealing with.

Think of the A-Number as the case number for your entire immigration history, not one form or one filing alone. A single petition may generate its own separate tracking number, but your A-Number is attached to you across every filing you make from that point forward.

A-Number vs Alien Number vs USCIS Number

"Alien Registration Number," "A-Number," "A#," and "alien number" all refer to the same number. USCIS also uses the term USCIS Number on newer documents. According to USCIS, the USCIS Number is the same number as your A-Number, printed without the leading "A." If a form or card shows "USCIS#" instead of "A#," it is the same identifier under a different label.

How A-Numbers Are Formatted 

Your A-Number is the letter A followed by seven, eight, or nine digits. Many USCIS forms require the full nine-digit format, so if your number is shorter, you add zeros directly after the "A" until it reaches nine digits.

For example, A1234567 becomes A001234567, and A12345678 becomes A012345678. USCIS allows for this padding. So, if a form rejects your entry or a field expects exactly nine digits, the fix is almost always a missing zero, not a wrong number.

Who Is Assigned an A-Number

• Lawful permanent residents, including green card holders
• Asylees, refugees, and Temporary Protected Status beneficiaries receive an A-Number when their status is granted.
• Applicants with a pending or approved immigrant petition, such as Form I-130, Form I-140, or Form I-485.
• Most nonimmigrant visa holders, including H-1B, L-1, TN, E-2, and B-1/B-2 visitors, generally do not receive an A-Number unless their case connects to an immigrant petition, such as an approved I-140, or to a work-authorization filing.
• F-1 students are a common exception. Students who apply for Optional Practical Training or STEM OPT through an Employment Authorization Document are assigned an A-Number as part of that EAD filing, even without pursuing a green card.

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If you hold a temporary work visa and have never filed an immigrant petition or an EAD application, there is a reasonable chance you do not have an A-Number yet. That is normal, and nothing is missing from your file. Check the document types below to confirm either way.

Where to Find Your Alien Registration Number on Each Document

Your A-Number is in a specific spot on different types of document. Here’s where to look.

On a Green Card (Form I-551)

Your alien number on the green card is shown on the number on the front, next to your photo. If your card is older, look for the label "A#" in the same position instead of "USCIS#."

On an Employment Authorization Document (EAD)

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Your work permit shows the number in the same "USCIS#" field as the green card, on the front of the card.

On a USCIS Receipt or Approval Notice (I-797)

Many, though not all, versions of Form I-797 include the A-Number near the top right. If your notice does not show it there, check an accompanying document from the same filing before assuming the number is missing.

On an Immigrant Visa or Consular Packet

An immigrant visa stamp lists the A-Number as the "Registration Number," in the top right portion of the stamp. This applies only to immigrant visas issued through consular processing. A nonimmigrant visa, such as a tourist or student visa stamp, does not carry an A-Number at all.

On an I-94 or Notice to Appear

This is the one document in this set that generally will not show your A-Number. The number on your I-94 is an 11-character Admission Number issued by Customs and Border Protection at the time you entered the US, and it identifies your entry, not your immigration file overall.

Many nonimmigrant workers, including most H-1B, L-1, and TN holders, have an I-94 Admission Number and no A-Number at all. 

Certificate of Naturalization

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A Certificate of Naturalization also lists your A-Number, once you become a US citizen. The number stays the same, even though once you become a citizen, you don’t practically use your A-number anymore. 

A-Number vs USCIS Online Account Number

The Online Account Number connects you to your account on the USCIS website. It is not linked to your immigration history, and a form asking for your A-Number will not accept it as a substitute. But if a form asks for your account number specifically, check your USCIS profile rather than reusing your A-Number.

A-Number vs Green Card Number vs Receipt Number

These three numbers appear close together on an official mail and can be confusing. Here’s a side-by-side comparison; 

The major difference is that your A-Number does not change, even after a lost card or a status change. Your green card number changes with every replacement card, and your receipt number is different for every filing you make.

If you filed a green card application and later a naturalization application, those two filings have two different receipt numbers, and the same A-Number listed on both. When a form asks for a "case number" or "receipt number," use the 13-character code, not your A-Number.

What to Do If You Cannot Find Your A-Number

1. Check older USCIS notices and past filings first. Approval notices, previous receipt notices, and old visa stamps often have the number even when your current documents do not.
2. Log into your USCIS online account. If you created one during a prior filing, your A-Number is visible there without needing to dig through paperwork.
3. Request your records through the Freedom of Information Act if the above turns up nothing.

Requesting Records Through FOIA

To request records through the FOIA, go through the online system rather than mail, fax, or email for faster processing. You may have to wait for several weeks for a response.

Checking Your USCIS Online Account

If you have ever filed anything with USCIS online, or created an account to check a case, your A-Number is usually listed in your account profile. Check this before filing a FOIA request.

Contacting the USCIS Contact Center

You can also call the USCIS Contact Center to locate your A-Number, though a representative will typically ask you to verify identity with other case details first. This should be your last option if you don’t get results from the other two steps. 

USCIS Forms and Common Identifiers

Common Mistakes When Entering an A-Number on USCIS Forms

Most delays come from entering an A-number wrongly on USCIS forms. Here are some mistakes to avoid; 

• Missing the leading zeros: A form that requires nine digits will reject or flag a seven- or eight-digit entry. Add zeros directly after the "A" until the number reaches nine digits, as covered above.

• Confusing the A-Number with the receipt number: A field labeled "case number" or "receipt number" wants the 13-character code starting with three letters, not your A-Number. 

• Leaving the field blank instead of entering N/A: On Form I-9, someone without an A-Number or USCIS Number should enter "N/A" in that field and then provide either a Form I-94 Admission Number or a foreign passport with country of issuance, rather than leaving the field empty.
• Using an outdated or duplicate number after a records mismatch: In rare cases, a clerical error assigns someone more than one A-Number. If your documents show two different A-numbers across filings, resolve this with USCIS directly before submitting a new form.