A-Number on a Green Card: Where to Find It and How It’s Used

The A-Number on a green card is your Alien Registration Number, a seven- to nine-digit identifier the Department of Homeland Security assigns to you for life. On cards issued since May 2010, it appears on the front under the heading “USCIS Number.” On older cards, the same number is labeled “A#.” Either way, it’s the number that ties every immigration record in your name to a single file.

Where It Appears on the Card

Pick up your Permanent Resident Card (Form I-551) and look at the front. The current version, issued since January 30, 2023, prints the number under the heading “USCIS Number/A-Number,” with your photo on both sides of the card.1U.S. Citizenship and Immigration Services. 13.1 List A Documents That Establish Identity and Employment Authorization – Section: Permanent Resident Card Cards issued between May 2010 and January 2023 use the same “USCIS Number” label and repeat the number on the back. Cards older than that use “A#” instead, but the number itself hasn’t changed.

One thing to watch out for: the card number is not the A-Number. The card number is a 13-character code, three letters followed by ten digits, printed on the back of newer cards. It identifies that piece of plastic, not you. When you renew or replace the card, the card number changes and the A-Number does not.1U.S. Citizenship and Immigration Services. 13.1 List A Documents That Establish Identity and Employment Authorization – Section: Permanent Resident Card Putting the card number where the A-Number belongs is one of the most common filing errors, and it will hold up your case.

Other Places the Same Number Shows Up

If your card isn’t in front of you, the A-Number is on several other documents you may already have:

Whatever document you pull it from, the number will be the same. It doesn’t change when you switch categories, marry, change your name, or naturalize.

What to Do About Seven- or Eight-Digit Numbers

Older records were built with shorter A-Numbers, and yours may be only seven or eight digits. Most current electronic forms require exactly nine. Pad the front with zeros until you reach nine digits total: A12345678 becomes A012345678, and A1234567 becomes A001234567.2U.S. Citizenship and Immigration Services. Immigrant Fee Payment: Tips on Finding Your A-Number and DOS Case ID The N-400 instructions give the same guidance.4U.S. Citizenship and Immigration Services. Instructions for Application for Naturalization Zeros go in front, never behind. If you leave the field short or pad in the wrong place, the system may not match your record.

What You’ll Use the A-Number For

Naturalization

Form N-400 requires the A-Number on every page. The instructions say USCIS needs both your A-Number and your permanent resident date to process the application.4U.S. Citizenship and Immigration Services. Instructions for Application for Naturalization It’s how the agency pulls your full history to check residency, travel, and eligibility. An incorrect number can delay the case because officers have no efficient way to find your record without it.

Form I-9 at a New Job

When you start a job, Section 1 of Form I-9 asks how you’re authorized to work. If you check “lawful permanent resident,” you enter your A-Number in the space provided.5U.S. Citizenship and Immigration Services. Instructions for Form I-9, Employment Eligibility Verification Workers who check “alien authorized to work” can also use the A-Number as one of the acceptable identifiers.

Talking to USCIS

Worth knowing before you try: the USCIS online case status tool does not accept A-Numbers. It only takes the 13-character receipt number from your I-797C notice.6U.S. Citizenship and Immigration Services. Checking Your Case Status Online Where the A-Number does the work is on the phone or in person: the Contact Center and field office staff use it to pull your entire file. Other government agencies also use it when they query the SAVE system to confirm your status for benefits or licenses.7U.S. Citizenship and Immigration Services. SAVE

If You Can’t Find It Anywhere

Start with old paperwork. Prior green cards, work permits, approval notices, and any Form I-797C all carry the same A-Number, so any one of them will do.

If nothing turns up, request your immigration records from USCIS through a Freedom of Information Act or Privacy Act request. Since January 22, 2026, these requests must be filed online through first.uscis.gov; paper submissions are no longer accepted.8U.S. Citizenship and Immigration Services. Request Records through the Freedom of Information Act or Privacy Act You’ll create a USCIS account and specify that you’re asking for your A-Number or A-File. Narrower requests get processed faster than requests for a whole file.

You can also book an in-person appointment at a USCIS field office through the online appointment system or by calling the Contact Center. Bring identification, because the officer has to verify who you are before releasing the number. Appointments are free. Arrive no more than 15 minutes early, and don’t be late; missed appointments have to be rescheduled.

One Related Duty to Keep in Mind

Once you know your A-Number, you’re expected to use it when you move. Federal law requires most non-citizens to report a change of address within 10 days by filing Form AR-11 online, and the form asks for your A-Number so the update lands in the right file.9Office of the Law Revision Counsel. 8 USC 1305 – Notices of Change of Address If you miss the window, file anyway. USCIS mails hearing notices, approval letters, and replacement cards to the address on record, and a notice you never receive can cause real trouble.