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UAAlien Registration Number
The Alien Registration Number, also known as A-Number or USCIS-Number, is an identification number assigned to Green Card holders by US immigration authorities. We explain what the A-Number looks like, where you can find it, and what you can use it for in US government communication.
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What do I need the Alien Registration Number for?
When applying for your Green Card, you receive a “USCIS Number” from United States Citizenship and Immigration Services. You must always state this number in the further immigration process whenever you are asked for either an “Alien Registration Number,” “A-Number,” “USCIS#,” or “Alien Number.”
The Alien Registration Number is a lifetime identification number. It is required for many processes related to immigration and residency in the United States, including applying for a work permit or the extension of your Green Card.
What does an A-Number look like?
The A-Number consists of a total of nine digits, which are often separated by two hyphens. On documents, it is mostly used with the heading "USCIS#," but you can also find it under headings like “Registration Number” or “A#.”
Possible formats of Alien Registration Numbers are:
- 123-456-789 (typical Green Card number format)
- 123456789
- A123-456-789
- A123456789
If an A-Number is lower and does not include the full nine digits, it is preceded by zeros, which can look like this:
- 000-456-789
- 000456789
- A000-456-789
- A000456789
Non-immigrant visa holders, such as B-1 visitor visa holders, do not receive an A-Number, except for holders of F-1-student visas.
When do I get the A-Number?
Your Alien Registration Number will be assigned as soon as USCIS has started processing your Green Card application.
However, if you have already held a work permit in the USA in the past, e.g., because you are studying in the United States, you may already have an A-Number.
On which documents are A-Numbers found?
Your A-Number is usually found on all immigration documents, including the first notice from USCIS, the immigrant visa card in your passport, and the Green Card.
If you are looking for the A-Number on your Green Card, you will find it on both the front and the back of the card.
Do not confuse: A-Number and USCIS Case Number
The Alien Registration Number is listed on the physical Green Card under the heading USCIS#. This often leads to confusion, as there is also a “USCIS Case Number”.
Here are the differences between A-Number and USCIS Case Number at a glance:
| USCIS numbers | USCIS# | USCIS Case Number |
|---|---|---|
| Look | 9 digits, sometimes preceded by an A | 13 characters, starting with three letters, e.g., MSC or EAC |
| Use | Identification of an immigrant during Green Card applications, work permits, and other immigration issues | Status check of your immigration application in the USCIS Case Status Online Tool |
| Example | 123-456-789 | EAC-18-249-12345 |
For all correspondence, forms, and log-ins related to your relocation to the USA, check which of the two numbers is needed for which step. In most cases, it will be the A-Number.
