1What is an A-Number?
An A-Number, short for Alien Registration Number, is a unique ID the US government assigns to track a person's immigration file. It is 7 to 9 digits, usually written with an "A" prefix, as in A123456789. Once assigned, it stays with you permanently across every future filing, the way a case number follows a single file.
You typically receive an A-Number the first time you file certain applications, most commonly an employment authorization request, an adjustment of status, or an immigrant petition. Green card holders carry it on the back of their card. It is the number USCIS uses internally to find every record connected to you, which is why it shows up on so many forms.
2Where do you find your A-Number?
The A-Number appears in different spots depending on which document you are holding. It is not always labeled clearly, which is why people miss it.
- Green card (Form I-551): printed on the back, sometimes labeled "USCIS#" which is the same number
- Employment Authorization Document (EAD): on the front, labeled "USCIS#"
- Immigrant visa or I-485 receipt: listed in the case details
- I-797 notices: often shown near the beneficiary name on approval notices for immigrant petitions
- Prior USCIS correspondence: any decision letter on an immigration benefit usually carries it
3A-Number vs USCIS case number vs receipt number: what is the difference?
A-Number: Identifies You
7 to 9 digits with an "A" prefix. Permanent. Tied to your immigration file as a person, not to any single application. The same A-Number follows you across every filing for the rest of your life.
Receipt Number: Identifies One Filing
13 characters: three letters (service center) plus ten digits, like WAC2212345678. A new one is generated for every petition or application. This is what you enter into the USCIS case status tool.
USCIS Online Account Number
A separate number tied to your myUSCIS online account, not your physical file. It is used to link paper filings to your online account and is not the same as your A-Number.
These three get mixed up constantly because they all look like long strings of characters and all come from USCIS. They track completely different things. The A-Number identifies you, the person, for life. A receipt number identifies one specific filing. The terms get blurred because, confusingly, the "USCIS#" on your green card is the same number as your A-Number.
4When do you actually need your A-Number?
You need it whenever a form asks for it, and adjustment-of-status paperwork asks for it everywhere. If you are filing or tracking an I-485 adjustment of status, the A-Number ties your EAD, advance parole, and the green card itself back to one file, so getting it right matters. A transposed digit can split your records and slow everything down.
It also comes up with immigration court, with travel documents, and any time you contact USCIS about your overall file rather than one specific receipt. If a job offer hinges on an employer sponsoring you, it is worth confirming that employer actually files immigration paperwork before you start collecting numbers. You can check a company's H-1B and green card sponsorship history against public DOL and USCIS data first.
Make sure the employer behind your case actually sponsors. Check any company before you rely on it.
Check Sponsorship History5What if you cannot find your A-Number?
If you have ever held a green card, an EAD, or filed an immigrant petition, you have one, even if you cannot locate it. Check old USCIS decision letters and the back of any card you have held. Your immigration attorney or employer's legal team can also pull it from prior filings.
Not everyone has an A-Number. Many people on a straight H-1B who have not yet started the green card process do not have one assigned yet, and that is normal. It typically gets created when you file something that requires it, like the first green card stage. Until then, you use your receipt numbers to track individual petitions.
Written by
Jesse Johnson
Founder, ShouldApply
Founder of ShouldApply. I write about job search strategy, hiring, and how to spend your time on opportunities that actually fit. Full bio →
Keep Reading
Frequently Asked Questions
On a green card and EAD, yes. The field labeled "USCIS#" on those cards is the same 7 to 9 digit number as your A-Number. The naming is inconsistent across USCIS documents, which causes a lot of confusion, but the digits are identical. It is not the same as your USCIS Online Account Number, which is tied to your myUSCIS account rather than your physical immigration file.
No. An A-Number is assigned when you file certain applications, most commonly an employment authorization request, an immigrant petition, or an adjustment of status. Someone on a straight H-1B who has not started the green card process often does not have one yet. It typically gets created the first time you file something that requires it, and then it stays with you permanently.
An A-Number identifies you as a person and is permanent, following you across every filing for life. A receipt number is 13 characters and identifies one specific petition or application. You get a new receipt number for every filing, but your A-Number never changes. Use the receipt number to check the status of a single case and the A-Number to reference your overall immigration file.
There is no public lookup that returns your A-Number from your name. You find it on physical documents you already hold, such as the back of a green card, the front of an EAD, immigrant petition notices, or prior USCIS decision letters. If you cannot locate it, your immigration attorney or your employer's legal team can usually retrieve it from past filings on your file.
Free Tools
Related Posts
I-485 Processing Time in 2026
The adjustment of status step where your A-Number ties together EAD, advance parole, and the green card.
I-797 Approval Notice: What Each Type Means
How to read the USCIS notice that often carries your beneficiary details.
PERM Processing Time in 2026
The labor certification step before the immigrant petition stages.
Track the right numbers from the start.
Before you collect case numbers for a sponsorship, confirm the employer actually files. Check any company against public DOL and USCIS data.
Check Sponsorship History