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An Alien Registration Number (A-Number) is the 7- to 9-digit number DHS assigns to a noncitizen when it opens their immigration file, and it's printed on the front of green cards and Employment Authorization Documents (EADs), labeled "USCIS#" on current cards. The USCIS Number and the A-Number are the same identifier; the USCIS Number just drops the "A" prefix, and the person keeps it for life.
On Form I-9, the A-Number belongs in Section 1, where lawful permanent residents must enter it and other work-authorized noncitizens can use it. It doesn't go in Section 2. That's where you record the card's own document number, and mixing the two up is how a clean hire turns into an E-Verify mismatch. ICE lists a missing A-Number for a lawful permanent resident as a substantive violation in its August 31, 2026 inspection fact sheet.
Go by the label on the document, not the length of the number. Green cards and EADs each carry two long numbers, and only one of them is the A-Number.
| Document | Where the A-Number is | The other number on it |
|---|---|---|
| Green card (Form I-551) | Front, labeled USCIS# (A# or Alien # on older cards) | 13-character document number on the back |
| EAD (Form I-766) | Front, labeled USCIS# | 13-character card number, also on the front |
| USCIS notice (Form I-797) | Upper left, labeled A# or A-Number | Receipt number (starts with letters like IOE, SRC, or LIN) |
| Immigrant visa (MRIV) or I-551 stamp in a passport | In the visa's data block or the stamp text | Passport number |
| Form I-94 | Usually not on it | 11-digit admission number |
The A-Number is on the front in the USCIS# field. Flip the card over for the 13-character document number, which is the one Section 2 wants. Our green card number guide walks through every field on the card.
Both numbers sit on the front of an EAD, a few lines apart, so the swap is easy to make. USCIS# is the A-Number for Section 1. The card number is for Section 2, as M-274 Section 7.4.2 spells out. The EAD guide covers the category code and expiration fields too.
An I-797 approval or receipt notice prints the A-Number in the upper left, right next to the receipt number, so read the label before you copy anything. A machine-readable immigrant visa carries it in the data block, and a temporary I-551 stamp carries it in the stamp text. More on those in our Form I-551 guide.
USCIS has no public search that returns someone's A-Number, and neither employers nor E-Verify can look one up. The employee has to find it on their own records. These are the places it turns up, from fastest to slowest:
An employee who's waiting on a lost card doesn't have to stall the I-9. A lawful permanent resident can present a receipt for a replacement green card, and anyone can present other documents from the Lists of Acceptable Documents instead.
Four numbers get confused on these forms, and only the first belongs in the A-Number field.
| Number | What it identifies | Where it goes on Form I-9 |
|---|---|---|
| A-Number / USCIS Number (7 to 9 digits) | The person, for life | Section 1 |
| Receipt number (3 letters + 10 digits) | One application or petition | Never in the A-Number field |
| Card or document number (13 characters) | The physical card, new on every reissue | Section 2, document number |
| I-94 admission number (11 digits) | One entry into the U.S. | Section 1, as an alternative to the A-Number |
"USCIS Number" causes the most head-scratching, and the answer is simple. M-274 Section 3.0 says the USCIS Number is the A-Number without the "A," so A-123456789 and 123456789 are the same entry. A person keeps that number across renewals, and our article on whether an A-Number ever changes covers the rare files where two numbers show up.
Lawful permanent residents, including conditional residents, check the third box and must enter their A-Number or USCIS Number. Asylees and refugees check "an alien authorized to work" instead, even though many of them have an A-Number. In that fourth box the employee enters one of three things: the A-Number, the I-94 admission number, or a foreign passport number with its country. One is enough, per M-274 Section 3.0.
Copy the number exactly as it's printed, including any leading zeros. Many H-1B, L-1, and TN workers have no A-Number at all, and they correctly use the I-94 or passport option and leave the A-Number blank.
Section 2 records the document you examined: title, issuing authority, document number, and expiration date. For a green card that's the document number on the back. For an EAD it's the card number on the front. The A-Number doesn't go here, and if you're filling in the issuing authority, our issuing authority guide has the entry for every document.
"The A-Number on the EAD and the number in Section 1 have to match character for character," says Patricia Duarte, Director of Compliance at i9 Intelligence. "We see leading zeros dropped, or someone copies the receipt number from the approval notice instead of the USCIS number on the card itself."
ICE's August 31, 2026 fact sheet makes a missing A-Number for a lawful permanent resident a substantive Section 1 violation, and paperwork fines run $288 to $2,861 per form. The same list covers a noncitizen authorized to work who left the A-Number, I-94, and passport fields all blank. Section 1 errors have to be corrected by the employee, not HR. Our I-9 audit team finds the forms with a wrong or missing number and walks your team through getting each one fixed the right way.
On an EAD, both numbers sit on the front a few lines apart, and someone moving fast types the USCIS# into the Section 2 document number field. On a green card the mistake runs the other way, because the employee copies the 13-character number from the back into Section 1. Either one can trip the E-Verify case, because the form no longer matches the document.
On an I-797 notice, the receipt number and the A-Number sit side by side in the upper left, and the receipt number looks more official. A Section 1 entry that starts with three letters is almost always a receipt number.
When Section 1, the card, and the E-Verify case don't match, check the card first before changing anything on the form. The fix is usually a typo, a dropped zero, or the wrong number from a notice. The employee makes Section 1 corrections, then initials and dates them, per the USCIS correction steps. Our guide to E-Verify mismatches covers what to do once a case is open.
It's the 7- to 9-digit number DHS assigns to a noncitizen when it opens their immigration file, also called the A-Number or USCIS Number. It appears on green cards, EADs, and USCIS notices and doesn't change.
Look at the front of your green card or EAD for the USCIS# field, or the upper left of any USCIS notice. Without those, check your USCIS online account or ask the attorney who filed your case.
Yes. The USCIS Number is the A-Number without the "A" prefix, so A-123456789 and 123456789 are the same identifier.
No, they're two different numbers. The A-Number is on the front of the card and identifies the person. The 13-character document number on the back identifies that specific card and changes when the card is replaced.
There's no public lookup. Employers can't search for one, and E-Verify doesn't return it. The employee finds it on their own documents or USCIS account.
Lawful permanent residents, asylees, refugees, and EAD holders do. Many temporary workers on H-1B, L-1, or TN status don't, and they complete Section 1 with an I-94 or foreign passport number instead.
They're different numbers. The I-94 admission number is 11 digits and identifies one entry into the U.S. The A-Number identifies the person's immigration file.
No. The cards expire, and the card numbers change, but the A-Number on each new card is the same.
Our compliance team can look at the card, the form, and the E-Verify case with you and tell you which number goes where.