What an Alien Number Is and Why It Matters
An alien number on a green card is a unique identifier assigned to a noncitizen who has been granted lawful permanent residence in the United States. This number appears on the front of the physical green card and within multiple fields on the card layout. It is used by government agencies, employers, banks, and service providers to link records, verify identity, and manage immigration and tax processes. Understanding where to locate this number and how it differs from other identification codes helps reduce errors when completing forms, applying for work, or proving status.
Where to Find the Alien Number on Your Green Card
On most printed green cards issued after 2010, the alien number appears in the smallest text box at the top right of the front side. It is usually labeled A# or Alien Number and is followed by a 7- or 8-digit code that may include letters. On the back of the card, there is no alien number; instead, you will find other details such as the expiration date and codeline. If your card shows USCIS Case Number and Receipt Number elsewhere, those are separate identifiers and are not the alien number.
Format Examples and Location Summary
The code typically follows formats such as 12345678 or AB123456, depending on when the card was issued. For clarity, locate the field labeled A# or Alien Number. If this field is blank or missing, contact USCIS before using the card for employment or government services. Keeping a clear copy or screenshot of this section helps when filling out repeated applications or online profiles.
How the Alien Number Is Used in Daily Life
Employers request the alien number on Form I-9 and related employment documents to establish work eligibility and to report new hires to government systems. On tax forms, the alien number ties your income and filings to your immigration status, ensuring correct handling of nonresident or resident tax rules. Government agencies, schools, and financial institutions also use this identifier to cross-check records, prevent fraud, and protect sensitive data. Because the number is unique and persistent, it reduces confusion when multiple agencies share information about the same person.
Differences Between the Alien Number and Other Card Codes
Several numbers appear on a green card, and it is important to distinguish the alien number from other identifiers. The USCIS Case Number is tied to the application that gave you the card, the Receipt Number is an initial processing code, and the File Number may appear on older documents. The alien number remains on the card for the duration of your permanent resident status, even if your biometrics or other details change. Knowing which code is which prevents delays when updating records or responding to government inquiries.
Quick Comparison of Green Card Identifiers
| Identifier | Label on Card | Primary Use | Changes Over Time |
|---|---|---|---|
| Alien Number | A# or Alien Number | Long-term identity for employment, taxes, and benefits | Persists across renewals unless status changes |
| USCIS Case Number | USCIS Case Number | Tracks a specific application or petition | Unique to each application |
| Receipt Number | Receipt Number | Initial acknowledgment of filing | Used until case is adjudicated |
| File Number | File Number | Legacy agency tracking identifier | May appear differently on older cards |
When to Double-Check Your Alien Number
Always verify the alien number before submitting forms, starting a new job, or applying for benefits. Even a single-digit error can cause processing delays, mismatched records, or the need to resend documents. If your card has been renewed multiple times, confirm that the number has not changed due to reissuance or status adjustments. When in doubt, reference the number exactly as it appears on the card and avoid transposing digits or omitting letters.
Correcting or Replacing an Alien Number Issue
If the number is missing, illegible, or incorrect on your green card, contact USCIS to request a replacement card through the appropriate process. Gather supporting documents, such as your current green card, identification, and any related case receipts, before filing a request. During corrections, provide the alien number exactly as it appears to maintain continuity in agency systems. After receiving a corrected card, update relevant employers, tax authorities, and service providers with the accurate identifier.
Long-Term Value of Keeping Your Alien Number Accessible
Retaining a documented record of your alien number supports smoother transitions between jobs, educational opportunities, and government services. It simplifies future applications, renewals, and background checks by providing a consistent reference tied to your lawful permanent resident status. Treat this identifier with the same care as other important personal codes, and store copies securely both digitally and physically.