Alien Number vs. USCIS Case Number: What’s the Dif

--------- Alien Number vs. USCIS Case Number: What’s the Difference?

Apr 5, 2025

Share this article:

If you've ever navigated the U.S. immigration system, you've probably come across two important numbers: the Alien Registration Number (often just called an "Alien Number" or "A-number") and the USCIS Case Number. At first glance, they might seem similar or even interchangeable. But trust me, they're completely different numbers used for very different purposes. Let's unpack exactly what they are, how to find them, and why each one matters.

Alien Number (A-number): Your Permanent Identification

The Alien Number, or A-number, is essentially your unique identifier within the U.S. immigration system. Think of it like your Social Security number, but specifically for immigration purposes. It's a permanent number assigned to immigrants (or "aliens," to use the formal legal term) that sticks with you throughout your entire immigration journey and even beyond.

An Alien Number typically looks something like this: A123456789. It's a nine-digit number preceded by the letter "A". Once assigned, your A-number stays the same, regardless of how many immigration applications you file or how your status changes.

Who Gets an Alien Number?

Not everyone dealing with U.S. immigration automatically gets an A-number. Here’s the usual breakdown:

Permanent Residents: If you have a Green Card or have applied for permanent residence, you'll definitely have an A-number.
Certain Visa Holders: Some nonimmigrant visas, like those granted asylum or refugee status, will also have an A-number.
Employment Authorization (EAD) Holders: If you're authorized to work, your EAD card will usually display an A-number.

If you're here temporarily on a tourist, student (F-1), or certain work visas (like H-1B), you probably don't have an A-number, as these categories generally don't get one unless they apply for something more permanent.

Where Can You Find Your Alien Number?

You can find your A-number on several immigration documents, including:

Green Card (Permanent Resident Card): It's prominently displayed.
Employment Authorization Document (EAD): Listed under USCIS number.
Immigrant Visa Stamp: If you received your immigrant visa from a U.S. embassy abroad, your visa stamp will include your A-number.
USCIS Notices: Notices like Form I-797 for approval of permanent residency or adjustment of status.

USCIS Case Number: Tracking Your Applications

Now, let’s switch gears to the USCIS Case Number, also known as the Receipt Number. Unlike the A-number, which follows you forever, the USCIS Case Number is tied specifically to an individual immigration application or petition. Every time you file something with USCIS (the United States Citizenship and Immigration Services), they generate a new Case Number just for that application.

The USCIS Case Number typically looks like this: LIN1234567890 or WAC1234567890. Notice it's a combination of letters and numbers. Each part of this Case Number actually tells you something useful:

Service Center Code: The first three letters (e.g., WAC, LIN, SRC, EAC, MSC) indicate which USCIS service center is handling your application.
Fiscal Year: The next two digits represent the fiscal year when USCIS received your case.
Workday: Then comes the three-digit workday number showing the exact day of the fiscal year your application was received.
Sequential Number: Finally, you have a unique five-digit number representing your application's place in line on that day.

Who Receives a USCIS Case Number?

Everyone who files an application or petition with USCIS will get a case number. Here are common examples:

I-130 Petition for Alien Relative: Used by U.S. citizens or permanent residents sponsoring family.
I-485 Application for Adjustment of Status: To become a permanent resident.
I-765 Application for Employment Authorization: For work permits.
I-129 Petition for Nonimmigrant Worker: For H-1B, L-1, and similar employment visas.

Essentially, any time you submit paperwork to USCIS, expect to receive a USCIS Case Number.

Where Can You Find Your USCIS Case Number?

Your USCIS Case Number is always clearly indicated on the following:

Receipt Notice (Form I-797C): This is usually the first communication you receive after filing any application. It contains your case number prominently at the top.
Online USCIS Case Status Tool: You can check your case status using this number.

The Key Differences: Alien Number vs. USCIS Case Number

At this point, you probably see the fundamental differences. To recap clearly:

Alien Number is permanent and personal, identifying you as an individual in the immigration system.
USCIS Case Number is temporary and application-specific, identifying only a particular case or petition you've filed.

Think of your Alien Number as your personal ID and the USCIS Case Number as the "ticket number" you get when submitting a specific immigration form. You’ll keep your Alien Number forever, while you might accumulate many USCIS Case Numbers over the years.

Why Does This Difference Matter?

Knowing the difference is crucial for practical reasons. Here's why:

Tracking Applications

To check the status of your immigration applications, you must use the USCIS Case Number. The online USCIS case status system does not recognize A-numbers because they're not linked to any one particular application, but rather your entire immigration record.

Identifying Documents

If you lose your immigration documents or need replacements, your Alien Number is your best friend. It provides USCIS a quick reference to your full immigration history.

Communication with USCIS

When contacting USCIS about a particular case or application, always use your USCIS Case Number. If you need information about your overall immigration status or previous filings, your Alien Number will help the immigration officer pull your records quickly.

Real-Life Scenario: Alien Number vs. USCIS Case Number

Imagine you filed an I-485 adjustment of status application to become a permanent resident. USCIS sends you a Form I-797 receipt notice with your USCIS Case Number. While your application is pending, you receive an Employment Authorization Document (EAD), which includes your Alien Number.

Your USCIS Case Number: Use this to track your I-485 application status.
Your Alien Number: Keep this handy for all future applications or if you need to renew your EAD.

When your Green Card is approved, you still retain the same Alien Number assigned at the start, but your USCIS Case Number is now a past reference. Any future applications (like citizenship through N-400) will generate new USCIS Case Numbers, but your Alien Number remains constant.