Alien Registration Number, Explained

Understanding the difference between your A-number and your USCIS case number

After your initial application for a green card, you’ll be asked to provide your Alien Registration Number (also called an “A-number,” “A#,” or “USCIS number”) on any forms or petitions you file with U.S. Citizenship and Immigration Services (USCIS). So what is an A-number, and where do you find it?

In a nutshell, Alien Registration Numbers are identification numbers for non-citizens. It’s a way for the U.S. government to keep track of all the different immigration forms and petitions that a person might file over the years. Every immigrant gets a unique number, which they keep for life.

In this guide, you’ll learn about:

  1. Who gets Alien Registration Numbers
  2. When you’ll receive your Alien Registration Number
  3. How to find your Alien Registration Number
  4. The difference between “A” Numbers and USCIS case numbers

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Who Gets an Alien Registration Number?

Alien Registration Numbers are assigned to everyone who applies for a green card, regardless of whether they’re eligible through family ties, employment, or as a refugee or asylee. All immigrants — meaning anyone who intends to live permanently in the United States — get an Alien Registration Number.

Most non-U.S. citizens who are in the United States temporarily, such as on a business or tourist visa, don’t get an Alien Registration Number. That’s because they’re seen as short-term visitors, not permanent immigrants.

There’s one exception: People on F-1 student visas who get work authorization are given an Alien Registration Number, even though they aren’t applying for a green card. Why do students with work authorization get an Alien Registration Number while other foreign workers don’t? We’ve asked around and can’t seem to find a satisfactory answer. Sometimes the U.S. immigration system is quirky.

With Boundless, you don’t have to worry about remembering form numbers or which specific forms you need for your situation. You simply answer a series of questions online — typically within just a couple of hours, compared with days or weeks the traditional way — and the completed forms arrive at your doorstep. Learn more about our services, or find out if you qualify for a green card.

When Do I Get an Alien Registration Number?

Most people are first given an Alien Registration Number when they apply for a green card. However, if you previously gained work authorization while in the United States on an F-1 student visa, you might already have been issued an A-number. This is most likely to be the case if you worked under the Optional Practical Training program after finishing your studies.

If you’re applying for a marriage green card from inside the United States, your Alien Registration Number will be included on the receipt notice you receive from USCIS after filing your green card application form.

If you’re the spouse of a U.S. citizen, you’ll file your green card application form — officially called the I-485 — right away, and get your A-number about 30 days after beginning the application process. If you’re the spouse of a green card holder, you won’t file your I-485 until your your I-130 petition is approved and an immigrant visa is available, so you won’t get an A-number until about a year into the process.

If you’re applying for a marriage-based green card from outside the United States, your Alien Registration Number will be assigned to you when you attend your consular interview at the U.S. consulate. Regardless of whether your spouse is a U.S. citizen or a green card holder, you’ll receive some paperwork with your A-number during the consular interview. You’ll also be able to find your Alien Registration Number in the visa the consulate stamps in your passport.

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Where Can I Find My Alien Registration Number?

Once you’ve applied for a green card, your Alien Registration Number will be on all of the documents that USCIS sends you, including the notice you get telling you that USCIS has received your green card application. You’ll also see your Alien Registration Number on any, approval notices, and essentially all correspondence you get from USCIS.

On most forms that you’ll receive from USCIS, your Alien Registration Number will be labeled “A#” and posted prominently near the top of the first page.

The alien registration number on an immigrant data summary
(Source: USCIS)

If you apply from outside the United States, you’ll find your A-number on the Immigrant Data Summary and USCIS Immigrant Fee handout that you’re given when you attend your consular interview. You’ll also find your A-number on the visa stamped in your passport once your application is approved.

Alien Registration Number on U.S. Visa
(Source: USCIS)

Once you get your physical green card, your Alien Registration Number (labeled “USCIS#”) will be on both the front and the back of the card.

IMPORTANT! If you’ve lost your Alien Registration Number, and can’t find any USCIS documents, visas, or other paperwork that might contain it, you can use the Freedom of Information Act (FOIA) system to obtain a copy of your immigration file, which will include your A-number. You can also schedule an InfoPass appointment at your local USCIS office and ask for help. (Note that self-scheduled appointments are being phased out, so this option won’t be available to everyone.)

Boundless stays with you until the green card finish line, helping you keep on top of interview preparation, follow-on forms, and every other important milestone along your immigration journey. Learn more, or check your eligibility for free.

A-Numbers vs. USCIS Case Numbers

Your Alien Registration Number isn’t the only number you’ll see on your receipt notices. You’ll also have a USCIS case number, or receipt number, which is used to track your specific application and to check your application status online.

Think of it this way: The Alien Registration Number is assigned to you, while your case number is assigned to your application. If, for example, you apply for a green card now and apply for U.S. citizenship in the future, your two applications will have different USCIS case numbers, but your individual A-number will remain the same.

You can tell your A-number and your USCIS case number apart by how they look. Your A-number is always a 7, 8, or 9-digit number. Your USCIS case number, on the other hand, is a 13-character code beginning with 3 letters (such as “MSC” or “EAC”) and then 10 numbers.

Confusingly, you’ll sometimes see “USCIS number” or “USCIS#” — without the “case” — used to refer to your Alien Registration Number. Make sure you double-check which number you need to use!

IMPORTANT! The Alien Registration Number isn’t the same thing as a Social Security Number (SSN), which is used by the Internal Revenue Service and the Social Security Administration to keep track of U.S. workers’ income, taxes, and benefits. You can apply for an SSN along with a work permit as part of your green card application.