Alien Registration Number (A-Number)

#What this actually means

Your A-Number is basically your immigration system ID. It's an 8- or 9-digit number (always starting with the letter "A") that USCIS assigns to you when you first interact with the immigration system in a meaningful way — filing an application, getting a green card, being placed in removal proceedings, etc.

Think of it like a Social Security number, but for immigration. Once you have one, it follows you through every application, every status change, every interaction with USCIS. It's how they pull up your entire history.

#Where to find yours

Your A-Number shows up in several places:

• On your green card (front of the card, labeled "USCIS#" or "A#")
• On your Employment Authorization Document (EAD/work permit)
• On any Notice of Action (Form I-797) you've received from USCIS
• On the stamp in your passport if you've had one placed by CBP or USCIS

#Why it matters

Every immigration form you file will ask for your A-Number if you have one. Using the wrong number — or leaving it blank when you have one — can cause processing delays or even get your application flagged. If you've had any prior immigration history (including a previous visa application at a consulate), you likely already have an A-Number assigned.

#Key things to know

• Not everyone has one yet. If you've never filed an immigration application or been in proceedings, you may not have been assigned one. That's fine — just leave the field blank on forms.
• Your A-Number and your USCIS Online Account Number are different things. Don't mix them up on forms.
• If your number is only 8 digits, add a zero at the beginning when a form asks for 9 digits.