The USCIS A-Number shows up on almost every immigration form, usually followed by the words if any, which is exactly why people get confused. It is a single number that ties your immigration history together, and it is easy to mix up with the other numbers on your notices.
As of October 29, 2026, this guide explains what the A-Number is, where to find it, and how it differs from the USCIS Number, the receipt number and the online account number.
- The A-Number is a unique seven-, eight- or nine-digit number DHS assigns to identify a person's immigration record.
- It begins with an A and appears on correspondence from DHS or USCIS.
- Green cards issued after May 10, 2010 list a 9-digit USCIS Number on the front.
- Form I-9 treats the USCIS Number and the A-Number as the same entry for permanent residents.
- A receipt number is 13 characters, three letters and 10 numbers, and tracks one application.
- A USCIS Online Account Number exists only if you have a receipt number beginning with IOE, and it is not an A-Number.
What is an A-Number?
The USCIS glossary defines the Alien Registration Number, or A-Number, as "a unique seven-, eight- or nine-digit number that the Department of Homeland Security assigned to an alien" (USCIS, Glossary).
USCIS form instructions explain what it is for: "We use your A-Number to identify your immigration records." They add that "it begins with an 'A' and can be found on correspondence you have received from the Department of Homeland Security (DHS) or USCIS" (USCIS, Form I-90 Instructions).
Where can you find yours?
Start with documents DHS or USCIS has sent you, since the instructions point to "correspondence" from them. If you are a permanent resident, your green card is the easiest place to look. The glossary describes the USCIS Number as "a unique, 9-digit number assigned to an alien by the Department of Homeland Security that is listed on the front of Permanent Resident Cards (Form I-551 or Green Card) issued after May 10, 2010" (USCIS, Glossary).
If you have lost your card, our guide to renewing or replacing a green card with Form I-90 covers what to file. If you are abroad without it, see our guide to a lost green card abroad.
Is the USCIS Number the same as the A-Number?
For a permanent resident filling out forms, they work as one. The glossary entry for the USCIS Number says "see also Alien Registration Number or Alien Number." The Form I-9 instructions go further: "If you select 'lawful permanent resident,' enter your 7- to 9-digit USCIS Number (A-Number) in the space provided" (USCIS, Form I-9 Instructions). Workers who select "an alien authorized to work" may enter a "USCIS Number/A-Number (7 to 9 digits)," a Form I-94 admission number, or a foreign passport number with the country of issuance (same).
How is it different from a receipt number?
A receipt number tracks one filing. The glossary says it "is a unique 13-character identifier USCIS provides for each application or petition it receives," and that it "consists of 3 letters, such as EAC, WAC, LIN, SRC, NBC, MSC or IOE, with 10 numbers" (USCIS, Glossary).
| Number | Identifies | Format | Changes? |
|---|---|---|---|
| A-Number | You and your immigration record | 7 to 9 digits, begins with A | Tied to you, not one filing |
| USCIS Number | You (on green cards after May 10, 2010) | 9 digits | Tied to you, not one filing |
| Receipt number | One application or petition | 3 letters + 10 numbers | New for each filing |
| USCIS Online Account Number | Your online filing account | Shown in your account | Only if you have an IOE receipt |
To check a case online, you need the receipt number, not the A-Number. USCIS says "to check your case status using our online tool, you have to have your case receipt number," and that you "should omit dashes" when entering it (USCIS, Checking Your Case Status Online). Our guide to I-797 notices and case status shows where each number appears on a notice.
What about the USCIS Online Account Number?
It is a separate number for your online account. USCIS gives it to people who file online, or who mail a form and then receive an Account Access Notice. "You will only have a USCIS Online Account Number (OAN) if you previously filed a form that has a receipt number that begins with IOE." If you filed by mail, "you can find your OAN at the top of the Account Access Notice we sent you." And the instructions are explicit: "The OAN is not the same as an A-Number" (USCIS, Form I-485 Instructions).
What if you do not have one?
Say so. Form instructions say, "If you do not have an A-Number, type or print 'N/A'" (USCIS, Form I-90 Instructions). The same if-any wording appears on the I-485 and I-765 instructions, so the forms expect that some filers will not have one. Never substitute a receipt number or online account number.
Where do forms ask for it?
In more places than people expect. On Form I-90, it is the very first item: "Part 1. Information About You Item Number 1. Alien Registration Number (A-Number) (if any)" (USCIS, Form I-90 Instructions). The I-485 instructions also ask you to "lightly print your name and A-Number (if any) on the back of the photos" you submit (USCIS, Form I-485 Instructions), and the I-765 instructions ask for it as well, with the same explanation that USCIS uses it to identify your immigration records (USCIS, Form I-765 Instructions).
When you start work, your employer's Form I-9 may also ask for it, as described above. The I-9 instructions also state that your employer "may not ask for documentation to verify the information you entered in Section 1" (USCIS, Form I-9 Instructions).
A simple habit helps, especially if you have several cases open at once, such as an I-140, an I-485, a work permit and a travel document: keep a short list of your A-Number, each receipt number and its form type, and your OAN if you have one, so you always enter the right number in the right field.
Why does the A-Number matter?
Because it links your filings together. When you write it at the top of extra pages, as the instructions ask ("type or print your name and Alien Registration Number (A-Number) (if any) at the top of each sheet"), it helps USCIS match the pages to your record (USCIS, Form I-485 Instructions). Using the same number every time, and never substituting a different one, keeps that match straightforward.
What should you do if your numbers do not match?
Check the source document first. If two USCIS notices show different A-Numbers for you, or a form was filed with the wrong number, do not simply pick one and move on. Gather the notices, note which number appears on which document, and raise it with the attorney handling your case or with USCIS before your next filing, so that every later form carries the correct number.
What this means for you
- Look on DHS or USCIS correspondence, or the front of your green card, for your A-Number.
- Use the same A-Number consistently on every form, and write it on extra pages.
- Use your receipt number, not your A-Number, to check case status.
- Treat your OAN as an account number only.
- If you have never been assigned an A-Number, write N/A.
- Keep your address current with USCIS so correspondence reaches you; our guide to the AR-11 change of address explains how.
Where to start
If you are preparing a green card filing, our free evaluation at /evaluate/ checks which categories fit your profile, and Frank, our AI assistant at /frank, answers questions about the forms along the way. Petitions are reviewed and filed by our partner law firm, Lai & Turner.
Sources
All checked October 29, 2026.
- USCIS, Glossary. Alien Registration Number; USCIS Number; receipt number.
- USCIS, Form I-90 Instructions. Purpose of the A-Number; begins with A; where to find it; N/A if none.
- USCIS, Form I-485 Instructions. Online Account Number; OAN is not an A-Number; extra sheets.
- USCIS, Form I-765 Instructions. A-Number (if any).
- USCIS, Form I-9 Instructions. USCIS Number (A-Number) for permanent residents and authorized workers.
- USCIS, Checking Your Case Status Online. Receipt number needed; omit dashes.
Frequently asked questions
What is a USCIS A-Number?
It is your Alien Registration Number, which the USCIS glossary describes as a unique seven-, eight- or nine-digit number that the Department of Homeland Security assigned to you. USCIS uses it to identify your immigration records across applications. Unlike a receipt number, it is tied to you rather than to one application, so the same A-Number appears across your filings.
Where can I find my A-Number?
USCIS form instructions say it begins with an A and can be found on correspondence you have received from DHS or USCIS. On a green card issued after May 10, 2010, look for the USCIS Number on the front. If you have never been assigned one, USCIS forms tell you to write N/A rather than guess.
Is the USCIS Number on my green card my A-Number?
For practical purposes, yes. The USCIS glossary describes the USCIS Number as a unique 9-digit number listed on the front of green cards issued after May 10, 2010, and refers you to the A-Number entry. The Form I-9 instructions ask permanent residents for their 7 to 9-digit USCIS Number (A-Number) in a single field.
Is my receipt number the same as my A-Number?
No. A receipt number is a 13-character identifier for one application or petition, made of three letters such as EAC, WAC, LIN, SRC, NBC, MSC or IOE followed by 10 numbers. You get a new one for every filing. The A-Number identifies you, not a single case, and you use the receipt number to check case status online.
Does everyone have an A-Number?
No. USCIS forms ask for an A-Number only if you have one, and tell you to type or print N/A if you do not. Not everyone has been assigned one, and the forms are written with that in mind. Do not invent a number or use a receipt number or online account number in its place.
Green Card Guide AI is not a law firm and this article is not legal advice. It describes evidence-building strategy in general terms; your attorney determines what belongs in your petition and how it's argued.
