A-Number on a Passport: Where to Find It and When You Need It

The “A” you see on a passport marks an Alien Registration Number, a permanent identifier the Department of Homeland Security assigns to non-citizens who pass through the U.S. immigration system. It’s a seven- to nine-digit number preceded by the letter A (for example, A012345678), and on a passport it appears on the immigrant visa stamp placed inside the book, not on the passport’s biographical data page. Once assigned, it stays with the person for life, even after naturalization.

What the A Number Is

The Alien Registration Number, often shortened to A-Number or A#, is a personal tracking number the Department of Homeland Security creates the first time someone enters the U.S. immigration system. It links every application, approval, entry record, and status change to a single individual across USCIS, ICE, and CBP.¹

You may also see it labeled “USCIS#” on newer documents. It’s the same number.² Once assigned, it doesn’t change. It follows a person from a first immigration filing through permanent residency and, for those who naturalize, onto the Certificate of Naturalization. Even after the oath, the A number remains the key that opens the complete immigration file.

Where to Find It on a Passport

The A number does not appear on the biographical data page of a U.S. passport. It sits on the immigrant visa stamp (the visa foil) inside the passport used when the immigrant visa was approved. For most people, that was a foreign passport held before entering the United States as a permanent resident. On the foil, the A number is labeled “Registration Number” and appears in the upper-right area of the stamp.³

If you can’t spot it on the foil, the same number is printed on several other immigration documents:

Permanent Resident Card (green card), labeled “USCIS#” on newer cards.
Employment Authorization Document (EAD), also listed as “USCIS#.”
Certificate of Naturalization, shown as “USCIS Registration No.” or a similar designation.
USCIS notices and approval letters, printed near the top of any correspondence about your case.

The number may be seven, eight, or nine digits depending on when the record was created. If yours has fewer than nine digits, add zeros after the A until you reach nine total. A1234567 becomes A001234567.³

Why Some Passports Have One and Others Don’t

Only people who went through the U.S. immigration system have an A number. Someone born a U.S. citizen who never applied for any immigration benefit won’t have one. The number is assigned when a person applies for permanent residency, asylum, refugee status, or certain other immigration benefits.²

A typical path: someone abroad applies for an immigrant visa at a U.S. embassy. The embassy issues a visa foil showing the person’s A number and places it in their foreign passport. After arrival in the United States and issuance of the green card, the same number carries over. If that person naturalizes later, it appears again on the Certificate of Naturalization.

How It Differs From the Passport Number

A passport contains several numbers, and confusing them can hold up a filing.

Passport Number

The passport number identifies the document itself. On newer Next Generation U.S. passports, it starts with a letter followed by eight digits and appears in the top-right corner of the data page.⁴ It changes every time the passport is renewed or replaced, and it has nothing to do with immigration history.

Passport Book Number

Some passports also carry a passport book number, an inventory tracking number for the physical booklet, usually printed on the inside of the back cover. It, too, changes with each new book. Not every country’s passport includes one.

The key difference: passport numbers and book numbers belong to a physical document and expire with it. The A number belongs to the person and never changes.

When You’ll Need Your A Number

Several immigration processes require the A number, and not having it handy can stall a case.

Paying the USCIS Immigrant Fee

New immigrants must pay the USCIS Immigrant Fee online before the green card is produced. The payment system asks for the A number along with the DOS Case ID. Both can be found on the immigrant data summary, the USCIS Immigrant Fee handout provided at the visa interview, or the visa stamp itself.⁵ USCIS will not produce and mail the green card until this fee is paid.

Applying for Naturalization

Form N-400, the Application for Naturalization, asks the applicant to write the A number in the top-right corner of every page. USCIS uses it, together with the permanent resident date, to pull the complete file and verify eligibility. Pad shorter numbers with leading zeros the same way as for the Immigrant Fee.⁶

Other USCIS Filings

Virtually any form filed with USCIS asks for the A number. Renewing a green card (Form I-90), removing conditions on residence (Form I-751), petitioning for a family member (Form I-130), and requesting employment authorization all require it. Once assigned, it should appear on every future filing.

What to Do If You Cannot Find It

Losing track of an A number is common, especially when original documents are years old. Several paths can recover it:

Check the green card or EAD for the field labeled “USCIS#” on the front of the card.
Look at any approval notice, receipt notice, or Request for Evidence letter from USCIS. The A number is near the top.
Pull out the passport that holds the immigrant visa foil and find the “Registration Number” on the stamp.
Contact the U.S. embassy or consulate that issued the visa. If the immigrant data summary or Immigrant Fee handout never arrived with the visa packet, the post can provide a copy.³
Submit a Freedom of Information Act or Privacy Act request with USCIS to obtain a copy of the immigration file (the “A-File”), which contains the A number and the full immigration history.¹

Keeping the A Number Private

An A number is sensitive personal information. The Alien File system that stores records indexed by A number falls under the Privacy Act of 1974, which restricts how federal agencies collect, store, and share immigration records.⁷ Certain records receive additional confidentiality protections, including applications for asylum, refugee status, and visas connected to domestic violence or human trafficking.

Treat an A number the way you’d treat a Social Security number. Someone holding it, plus a few other personal details, could file fraudulent immigration petitions or interfere with the record. Keep it off social media and out of unsecured emails, and share it only with people who have a legitimate need. When submitting forms, use the official USCIS online filing system or secure mail rather than unencrypted channels.

1
U.S. Immigration and Customs Enforcement. ICE Freedom of Information Act (FOIA)
2
U.S. Citizenship and Immigration Services. A-Number/Alien Registration Number/Alien Number (A-Number or A#)
3
U.S. Citizenship and Immigration Services. Immigrant Fee Payment: Tips on Finding Your A-Number and DOS Case ID
4
U.S. Department of State. Information About the Next Generation U.S. Passport
5
U.S. Citizenship and Immigration Services. USCIS Immigrant Fee Payment Guide
6
U.S. Citizenship and Immigration Services. Form N-400 Instructions for Application for Naturalization
7
Federal Register. Privacy Act of 1974 – U.S. Citizenship and Immigration Services, Immigration and Customs Enforcement, Customs and Border Protection – 001 Alien File, Index, and National File Tracking System of Records