Your A-Number, short for Alien Registration Number, is the unique identifier the U.S. government assigns to track your immigration file. It is sometimes written as “A#” or “USCIS#,” and it usually looks like the letter A followed by eight or nine digits (for example, A123456789). Knowing your A-Number and where to find it matters, because USCIS, the immigration court, and other agencies use it to locate your records, and you will need it on most forms, letters, and case inquiries. This guide explains what the number is, where it appears, and how to find it if you are not sure you have one.
The short version
An A-Number is a 7 to 9 digit case number that identifies your immigration file. You can find it on your green card, your work permit, USCIS notices, and immigration court documents. Not everyone has one; it is generally assigned once you file certain applications or come into contact with immigration authorities. Keep it private, and use it consistently on every filing.
Key Takeaways
- The A-Number is your file’s unique identifier, written as the letter A plus 8 or 9 digits, used by USCIS and the immigration courts.
- It appears on your green card, Employment Authorization Document, USCIS notices, and immigration court paperwork.
- Not every immigrant has an A-Number; it is assigned in connection with specific filings or immigration encounters, and you should keep it confidential.
What is an A-Number?
The Alien Registration Number is a number the Department of Homeland Security uses to identify a noncitizen and the file that holds their immigration records. Because USCIS, U.S. Customs and Border Protection, U.S. Immigration and Customs Enforcement, and the immigration courts all draw from that file, the A-Number is the thread that ties your records together across agencies. The USCIS glossary defines it as the unique number assigned to a noncitizen by DHS.
On newer documents you may see it labeled “USCIS Number” or “USCIS#” instead of “A-Number.” They refer to the same nine-digit identifier. Older files sometimes show a seven or eight digit number; if yours is shorter than nine digits, you can add leading zeros after the “A” to reach nine digits when a form requires it.
Where do I find my A-Number?
The A-Number appears on most documents the government issues in your case. The most common places to look are:
- Permanent Resident Card (green card). The A-Number is printed on the front, often labeled “USCIS#,” and it also appears in the machine-readable text on the back.
- Employment Authorization Document (work permit). Your A-Number is shown on the card, typically near your photo and personal details.
- USCIS notices (Form I-797). Receipt notices, approval notices, and other correspondence usually list your A-Number near the top, alongside your receipt number.
- Immigration court documents. A Notice to Appear and other court paperwork show your A-Number prominently, because the court uses it to track your case.
- Immigrant visa and entry documents. If you were issued an immigrant visa, your A-Number appears on the visa and related stamps.
The A-Number is different from a USCIS receipt number, which begins with three letters (such as IOE, EAC, or WAC) and tracks one specific application rather than your whole file. Both are useful, but they are not the same thing.
Does everyone have an A-Number?
No. Many people who have never filed an immigration application or had contact with immigration authorities do not have one. An A-Number is generally created when you file certain applications, such as a green card application or a work permit request, or when you are placed in removal proceedings or otherwise encountered by immigration authorities. If you are early in a process, such as a U.S. citizen petitioner filing for a relative, you personally may not have an A-Number even though the beneficiary will be assigned one.
If you have filed before, you almost certainly have an A-Number even if you have lost track of it, and reusing the same number is important. Using a different or new number by mistake can fragment your records, which slows everything down.
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What if I lost my A-Number or my documents?
If you cannot find your A-Number, start with any immigration paperwork you still have, including old USCIS notices, copies of forms you filed, or court documents. If you once held a green card or work permit that was lost, the number would have been printed on it. Replacing a lost green card is a separate process we cover in our guide to green card replacement, and the replacement card will carry the same A-Number.
Keep your A-Number somewhere secure and private. It is sensitive information that, in the wrong hands, can be used to look up or interfere with your case. When you move, update your address with USCIS so notices that contain your A-Number reach you; we explain how in our guide to filing Form AR-11. And when you receive a visa bulletin update or any case notice, check that the A-Number matches the one on your other documents.
Frequently Asked Questions
Is the A-Number the same as my Social Security number?
No. They are completely separate. The A-Number identifies your immigration file; the Social Security number is issued by the Social Security Administration for work and tax purposes.
Is my A-Number the same as my green card number?
Your A-Number appears on your green card, often labeled “USCIS#.” The card also has a separate physical card number, so check the label to be sure you are reading the right one.
Does my A-Number ever change?
No. Once assigned, your A-Number stays with you and your file. You should use the same number on every filing.
What is the difference between an A-Number and a receipt number?
The A-Number identifies your overall file. A receipt number, which starts with three letters, tracks one specific application. You may have one A-Number but several receipt numbers over time.
How We Can Help
Small mistakes with case numbers can cause real delays, from misrouted notices to mismatched records. We help clients keep their filings consistent, locate an A-Number when it has been lost, and make sure every form references the right identifiers. Our founding attorney Denisse Ilabaca is Board Certified in Immigration and Nationality Law by The Florida Bar, a distinction held by fewer than two percent of Florida attorneys. If you are unsure about your A-Number or your case status, call us at (407) 917-2087 and we will help you get organized.
This article is provided for general informational purposes only and does not constitute legal advice. Reading it does not create an attorney-client relationship. For advice about your specific situation, consult a licensed immigration attorney.
