Last updated: November 9, 2025.
By Asel Williams, Esq. · Columbia Law School · Licensed immigration attorney
Alien Registration Number (A number)
The Alien Registration Number (A-number, A#, or USCIS#) or ARN is a unique seven- to nine-digit number identifying foreign nationals who have applied for immigration benefits.
This number is used to track a foreign national’s U.S. immigration status and history.
It is similar to a social security number and is an essential component of any immigration application or petition.
The alien number has several important features:
- Identification: It’s a unique number assigned to foreign nationals applying for immigration benefits. An A-number enables USCIS and other government agencies to identify immigrants, keep records, and process immigration applications.
- Tracking: enables tracking of an individual’s immigration history, including applications filed with USCIS or US Department of State.
- Reference: When contacting USCIS, applicants or their representatives need to provide the A-number to place inquiries or requests.
Typically, the A-number is assigned when an individual files an immigration petition with USCIS (for example, Form I-130 or Form I-129F), whether through an immigrant visa application, adjustment of status, or other immigration-related petition.
It remains unchanged throughout the individual’s life and any subsequent immigration applications or petitions filed.
Where to Find Your Alien number
Knowing where to find your A-number is critical for correctly completing immigration forms.
The A-number appears on a variety of immigration documents issued by USCIS and US Department of State.
Here are some of the documents where you can find your A-number:
- Form I-485 receipt notice: If you have filed Form I-485 (Application to Register Permanent Residence or Adjust Status) with USCIS, you will receive a hard copy notice by mail after the application is registered. A-number is listed under “USCIS Alien Number”.
- Biometrics notice: If you have filed an immigration application, USCIS typically schedules a biometrics appointment. A-number can be found on the biometrics appointment notice under “USCIS #”.
- Form I-129F approval notice: If you have an approved Form I-129F, Petition for Alien Fiancé(e), A-number can be found under “Beneficiary” field.
- Permanent Resident Card (Green Card): If you are a lawful permanent resident (green card holder), your A-number appears on the front of your Permanent Resident Card (Form I-551). A-number is listed under “USCIS#”.
- Naturalization Certificate: your A-number is listed on the naturalization certificate in the “USCIS Registration Number” field.
- Employment Authorization Document (EAD): Individuals who have been issued an Employment Authorization Document (EAD) under (c)(9) or (c)(8) category will have their A-number printed on the card. The A-number can be found under “USCIS#” field. Note: some nonimmigrants (such as F-1 students) may have been issued USCIS# for EAD purposes. This number is not always the immigration-related A-number. A-number is issued only when a foreign national applies for an immigration benefit (for example, family-based, or employment-based petition, asylum, TPS, etc.)
- Immigrant Visa: A-numbers are listed on immigrant visas issued by the U.S. Department of State and can be found under “Registration Number” field.
- Form I-797, Notice of Action: Form I-797 is a notification of action from USCIS that confirms receipt or approval of your application, petition, or request. If you got an I-797, your A-number will be listed in the top section of the notification, under “USCIS A#”.
- Form I-140, Immigrant Petition for Alien Worker: If you have an approved employment-based immigration petition (Form I-140 approval notice), your A-number can be found in the “Beneficiary” field.
- Asylum Application (Form I-589): A-numbers are assigned to asylum seekers when they file Form I-589, Application for Asylum and Withholding of Removal with USCIS. This number will be used in all subsequent immigration applications.
- Immigration court notices: If your case is currently pending before an immigration judge, you can find your A-number on all notices from the immigration court under “File #”.
The Alien Registration Number (A-number) is an important part of the US immigration system, acting as a unique identifier for non-citizens.
Understanding and locating your A-number is vital whether applying for a visa, adjusting your status, petitioning for a family member, or navigating other immigration processes.
This unique identification number not only allows USCIS to maintain and manage your immigration records, but it also ensures that your applications and petitions are processed efficiently.
Knowing where to find your A-number on various immigration documents will help you streamline your applications with USCIS.
To avoid delays or issues, always keep your A-number on file and include it in all related communications with USCIS or US Department of State.