Immigration Registration Number: What It Is and Where to Find It

An immigration registration number, better known as an Alien Registration Number or A-Number, is the unique identifier the Department of Homeland Security assigns to noncitizens so every agency handling their case can pull up the same file. It’s a seven-, eight-, or nine-digit number preceded by the letter “A,” and once you have one, it stays with you through every status change, from a first work permit through permanent residency and even after naturalization.1USCIS. A-Number/Alien Registration Number/Alien Number

What the Number Looks Like

The A-Number is all digits after the leading “A.” Most modern systems expect exactly nine digits. If yours is shorter, add a zero after the “A” and before the first digit so it fits the nine-digit format. A12345678 becomes A012345678.2USCIS. Immigrant Fee Payment – Tips on Finding Your A-Number and DOS Case ID Missing that leading zero is one of the most common reasons online submissions throw an error.

On Permanent Resident Cards issued after May 10, 2010, the same number is labeled “USCIS Number” or “USCIS#” on the front of the card.3USCIS. USCIS Number The label changed, the number did not. Whether a form asks for your A-Number, Alien Registration Number, or USCIS Number, you enter the same digits.

The number is your personal key to a physical file, called an Alien File or A-File, that the government keeps on your immigration history. That file holds your applications, biometrics, correspondence, and any enforcement actions tied to your case.

Who Gets One

Federal law requires most noncitizens who stay in the United States for 30 days or longer to register, and the A-Number is the identifier tied to that registration.4Office of the Law Revision Counsel. 8 USC 1302 – Registration of Aliens In practice, USCIS generates the number when an immigration benefit application, enforcement action, or other proceeding creates an A-File.

People who typically receive one include:

  • Lawful permanent residents, who get an A-Number when the green card is approved. The number prints on the card itself.
  • Anyone filing Form I-765 for a work permit.
  • Asylum seekers, whose number is assigned at the time they file and links their case through the full adjudication.
  • People in removal proceedings, whose A-Number tracks hearings and decisions.

Short-term visitors on tourist or business visas generally do not receive an A-Number. Their entry is tracked through the I-94 Arrival-Departure Record instead. An A-File is only opened if they later apply for an immigration benefit or face enforcement.

Where to Find Your A-Number

The number appears on almost every official document DHS has sent you. The most common places to check:

  • Permanent Resident Card (Form I-551). Printed on the front, labeled “USCIS#” on cards issued after May 2010 and “A#” on older ones. It also appears on the back.5USCIS. 13.1 List A Documents That Establish Identity and Employment Authorization
  • Employment Authorization Document (Form I-766). Printed on the front, using the same labeling convention as the green card.
  • Notice of Action (Form I-797). The receipt or approval notice USCIS sends after you file a form. The A-Number sits in the header area.
  • Immigrant visa package. The number is often on the Immigrant Data Summary page stapled to the front of the sealed packet you carried at entry.
  • Immigrant visa stamp inside your foreign passport.
  • Certificate of Naturalization (Form N-550). Even after you become a U.S. citizen, the A-Number is printed alongside a separate certificate number.

Not the Same as a Receipt Number

People routinely mix these up. A receipt number is a 13-character code that starts with three letters (like EAC, WAC, or IOE) followed by 10 digits, and USCIS assigns a new one to every application it receives.6USCIS. Receipt Number Your A-Number is all digits, stays the same across every filing, and follows you through your entire immigration history. If you’re filling out a form and the field asks for one but not the other, the difference matters.

How the Number Gets Used

The A-Number is the thread that links your records across three separate agencies: USCIS, Immigration and Customs Enforcement, and Customs and Border Protection. Each keeps its own records, and the A-Number is how they find yours. When you file any immigration form, you provide the number so the agency pulls your existing file instead of opening a new one. A wrong number or a blank field can cause misrouting and delays.

Employment Verification

Your A-Number comes up on Form I-9, which every U.S. employer must complete for new hires. Lawful permanent residents must enter their A-Number in Section 1. Noncitizens authorized to work in other categories may provide their A-Number, I-94 admission number, or foreign passport number.7USCIS. Form I-9, Employment Eligibility Verification

Status Verification for Benefits and Licenses

Federal, state, tribal, and local agencies use the Systematic Alien Verification for Entitlements (SAVE) system to check immigration status when someone applies for a benefit, license, or Social Security card. The agency runs your A-Number through SAVE to confirm your status.8USCIS. SAVE SAVE only verifies status. The agency granting the benefit still decides whether you qualify.

Online Case Tracking

USCIS online accounts use the 13-character receipt number as the primary case tracker, but your A-Number is what ties multiple pending applications together under one account.9USCIS. Checking Your Case Status Online

Recovering a Lost A-Number

Forgetting your A-Number is common, especially years after it was first issued. Work through these steps in order:

  • Look through old paperwork first. The number appears on almost every USCIS notice, approval letter, and card the agency has ever sent you, so even a years-old Form I-797 receipt will have it.
  • Log into your USCIS online account. If you created one for a previous filing, the number may show in your case history.
  • Call the USCIS Contact Center at 1-800-375-5283. A representative can look it up after verifying your identity.10USCIS. USCIS Contact Center
  • File a Freedom of Information Act request as a last resort, using Form G-639 or the online portal at uscis.gov/foia. USCIS notes that requesting specific documents rather than an entire A-File usually processes faster, but FOIA requests can still take weeks or months.11USCIS. Form G-639, Freedom of Information/Privacy Act Request

An immigration attorney can also request your A-Number from USCIS on your behalf, which often moves faster than a self-filed FOIA request.

Protecting the Number

Your A-Number is sensitive information. Combined with your name and date of birth, it could be used to file fraudulent applications, interfere with your pending cases, or support employment identity theft. Treat it with the same caution as a Social Security number.

  • Keep your green card or EAD on you as required by law, but leave approval notices and other documents that display the number at home unless you need them for a specific appointment.
  • Only share the number with USCIS, your employer for Form I-9 purposes, your attorney, or a government agency verifying your status through SAVE. Immigration scams often start with a request for document copies.
  • Avoid sending it over unencrypted email or text. Use a secure portal or hand it over in person.

If you think your A-Number has been compromised, report the identity theft at IdentityTheft.gov or call 1-877-438-4338, then contact the USCIS Contact Center to flag your account.12USAGov. Identity Theft Immigration identity theft can create lasting complications for future filings, so acting quickly matters.