Numbers & Documents
Alien Registration Number (A-Number): What It Is and Where to Find It
Your Alien Registration Number—almost everyone just says "A-Number"—is the single most important identifier the U.S. government uses to track your immigration history. It follows you from your very first filing through a green card and, in many cases, all the way to naturalization. If you have ever stared at a USCIS notice wondering which of the long strings of digits is the one people keep asking for, you are not alone.
An A-Number is a seven-, eight-, or nine-digit number, usually written with a capital "A" in front of it (for example, A123456789 or A 012 345 678). The newest numbers are nine digits; older records may show fewer, and you will sometimes see them padded with leading zeros so they line up to nine places. Whatever the length, it is yours and yours alone.
Below we walk through exactly where to find your A-Number on the documents you already have, what to do if your number seems to change format, and why getting it right matters on every form you file.
Key takeaways
- ✓The A-Number is your permanent personal identifier in the U.S. immigration system; you keep the same one for life.
- ✓On newer green cards and EADs it is printed as the nine-digit "USCIS#."
- ✓It is different from a receipt number (per-filing) and an online account number (per-login).
- ✓Write "N/A" if you have genuinely never been assigned one—do not guess.
- ✓Enter it identically on every form in a packet to avoid mismatches and delays.
What the A-Number actually is
Think of the A-Number as a permanent case file number for you as an individual. When the government opens an immigration record on a person—often the first time they apply for a green card, an immigrant visa, or certain other benefits—it assigns an Alien Registration Number that stays attached to that person's file forever. You do not get a new one each time you file something new; the same number is reused across petitions, applications, and even immigration court proceedings.
Because it is tied to your underlying file rather than to any single document, the A-Number is what lets an officer pull up your complete history in seconds. That is also why entering it incorrectly—or leaving it blank when you actually have one—can slow a case down: the system may struggle to connect your new filing to the records that already exist.
Not everyone has an A-Number. If you have never applied for a benefit that generates one, the field may genuinely not apply to you, and writing "N/A" is the correct answer rather than inventing a number.
Where to find your A-Number on common documents
On a Permanent Resident Card (green card), the A-Number appears on the front, often labeled "USCIS#" on newer cards. On these newer cards the USCIS number and the A-Number are the same nine digits—the card simply drops the "A" prefix.
On an Employment Authorization Document (EAD), look for the field labeled "USCIS#"; again, that nine-digit number is your A-Number. On older work permits it may be printed as "A#" instead.
On USCIS notices such as Form I-797, the A-Number is frequently printed near the top, sometimes beside your name and sometimes in a box labeled "A#" or "A-Number." On an immigrant visa stamp placed in your passport at a consulate, it is listed as the "Registration Number." And if you have ever received documents from immigration court, the A-Number is the number the judge and clerk use to identify your case.
A-Number vs. the other numbers on your paperwork
Immigration documents are crowded with numbers, and mixing them up is one of the most common mistakes we see. The A-Number is not the same as a USCIS receipt number (which starts with three letters like IOE or MSC and tracks a single application), and it is not the same as a USCIS online account number (a separate number tied to your myUSCIS login).
A quick way to keep them straight: the A-Number identifies you, the receipt number identifies a specific filing, and the online account number identifies your web login. When a form asks specifically for your "Alien Registration Number" or "A-Number," only the A-Number belongs there.
Why getting it right matters
Every box on a USCIS form is a chance to either help your case move smoothly or introduce a delay. Because the A-Number connects your new filing to your existing record, an error here can cause your application to be matched to the wrong file—or to no file at all—triggering follow-up questions or a Request for Evidence.
If you are filing multiple forms together, the A-Number should match exactly across all of them. Consistency signals to the officer that everything in the packet belongs to the same person, which is exactly the impression you want to create.
When you prepare documents with Asal, confirming that your A-Number is entered correctly and identically on every page is part of our standard review—small detail, big difference.
Verify the official details
Government fees, processing times, form editions, and rules change regularly. Before you rely on any figure, confirm the current information on the official government page.
Learn more about your immigration record on USCIS.govFrequently asked questions
Is the A-Number the same as my USCIS number?+
On current green cards and Employment Authorization Documents, yes—the "USCIS#" printed on the card is the same nine digits as your A-Number, just without the "A" prefix. Older documents may label it "A#" instead.
My A-Number has only eight digits. Is that a problem?+
No. Older A-Numbers were issued with seven or eight digits. When a form expects nine digits, you can add leading zeros (for example, write A012345678 for an eight-digit number) so it fits the format. The underlying number does not change.
Where is the A-Number on a green card?+
On the front of the card. Newer cards label it "USCIS#"; that nine-digit value is your A-Number. Some older cards print it separately as "A#."
What if I don't have an A-Number?+
Many people filing their first petition do not have one yet. If a form asks for it and you have never been assigned one, write "N/A" rather than leaving it blank or guessing a number.
Can my A-Number ever change?+
It should not. The number is tied to your permanent immigration file. If you ever see two different A-Numbers on your documents, flag it—occasionally a duplicate file is created in error and USCIS can merge the records.
Is my A-Number confidential?+
Treat it like a sensitive ID number. It is needed on immigration paperwork and by your representative, but you should not post it publicly or share it casually, since it links to your full immigration history.
Related resources
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Asal Immigration Services is a document preparation service operated by Asal Multi-Services LLC. We are not attorneys and are not authorized to practice law. We do not provide legal advice, explanations, opinions, or recommendations about legal rights, remedies, defenses, options, or strategies. We assist with the preparation of immigration forms based on information you provide. For legal advice, consult a licensed immigration attorney.