What Is a Resident Number on Your Green Card?

The “resident number” on a Green Card is a loose term that actually points to two different numbers printed on the card. The one people usually mean is the USCIS Number, also called the A-Number (Alien Registration Number): a unique nine-digit number that identifies you personally. The other is the card number, a 13-character code that identifies the physical card itself. Which one you need depends on who is asking.

The USCIS Number (A-Number)

Your USCIS Number is the nine-digit identifier assigned to you by the Department of Homeland Security. On Green Cards issued after May 10, 2010, it appears on the front of the card labeled USCIS#.¹ It is the same number as your Alien Registration Number (A-Number); newer cards simply display it under a different label.²

This number stays with you permanently. It follows you through every immigration filing, every status change, and even through naturalization. If you become a U.S. citizen, your old A-Number still links to your immigration file. When a form, employer, or agency asks for your “resident number,” “alien number,” “A-Number,” or “USCIS Number,” this is almost always what they want.

The Card Number

The card number is different. It is a 13-character code printed on the back of the Green Card within the machine-readable zone, and it identifies the specific physical card you were issued, not you as a person. If you lose your card and receive a replacement, you get a new card number, but your A-Number stays the same. Some older immigration guides call this the “Green Card number,” which is where much of the confusion around the term “resident number” comes from.

Finding Your A-Number If You Can’t Find the Card

Your A-Number appears on more documents than most people realize. If your card is missing or you’re away from it, one of these will usually have the number:

The Green Card itself (Form I-551). On cards issued after 2010, the USCIS Number is on the front. Older cards show the A-Number on both the front and inside the machine-readable text on the back.
Your immigrant visa foil in your passport. The A-Number is listed as the Registration Number. If it has fewer than nine digits, add a zero after the “A” and before the first digit to reach the nine-digit format.³
The immigrant data summary stapled to the front of the immigrant visa package, which lists the A-Number and DOS Case ID at the top.³
The USCIS Immigrant Fee handout given to you at your embassy or consulate interview, which displays both numbers in the upper-right corner.³
An Employment Authorization Document (EAD), if you have one.
Most USCIS notices and approval letters, which print the A-Number near the top.

If none of those are available, you can create or sign into a USCIS online account at myaccount.uscis.gov. The account links to your filing history and may display your A-Number in connection with any pending or completed cases.

Which Number to Enter on Forms

Mixing the two numbers up on an application can delay processing or trigger a rejection, so the direction is worth being precise about. Immigration forms and employment paperwork almost always want the A-Number (USCIS Number), not the card number.

Form I-9 for Employment

Every employer in the United States verifies work authorization using Form I-9. If you are a lawful permanent resident, you enter your A-Number (USCIS Number) in Section 1 of that form. Workers authorized under a different immigration status provide either their A-Number, Form I-94 admission number, or foreign passport number in the same section.⁴ Getting this wrong on the I-9 creates problems for both you and your employer, so check it against your card before your first day.

Immigration Filings

USCIS, Customs and Border Protection, and Immigration and Customs Enforcement all pull up your records using the A-Number. It is the thread that connects everything in your immigration file, from your first petition through any later applications you file. When a USCIS form asks for your “A-Number” or “USCIS Number,” enter the nine-digit number from the front of your card.

What the Resident Number Is Not

A few other numbers get confused with the resident number on a Green Card, and none of them substitute for it on immigration paperwork. A Social Security Number is a separate nine-digit identifier used for earnings, tax filing, and benefits.⁵ A state driver’s license number is an identifier only within that state’s motor vehicle system. Some cities also issue municipal identification cards to residents regardless of immigration status; those cards carry their own local ID numbers and do not confer any immigration status or replace federal documents. Immigration forms will not accept any of these in place of your A-Number.

Protecting Your Number

Your A-Number is tied to your entire immigration history. If someone uses it fraudulently, untangling the damage can take years and jeopardize your status. Treat it with the same care you give a Social Security Number. Keep a photocopy of your Green Card in a secure location separate from the card itself, so the number is available if the card is lost. Avoid sending your A-Number over email or unsecured channels, and be cautious about anyone requesting it outside of a clearly legitimate employment or government context.

1
U.S. Citizenship and Immigration Services. USCIS Number
2
U.S. Citizenship and Immigration Services. A-Number/Alien Registration Number/Alien Number
3
U.S. Citizenship and Immigration Services. Immigrant Fee Payment: Tips on Finding Your A-Number and DOS Case ID
4
U.S. Citizenship and Immigration Services. Instructions for Form I-9, Employment Eligibility Verification
5
Social Security Administration. The Story of the Social Security Number