What is an alien number?
An alien number - formally Alien Registration Number, often shortened to A-number - is the unique ID USCIS uses to track every non-citizen they interact with. Once assigned, it stays with you for life. The same A-number follows you from your first work visa application through naturalization. It does not change when you get a green card or when you naturalize.
The format is the letter A followed by 7, 8, or 9 digits. Older numbers had 7 digits; modern numbers have 9. USCIS pads shorter numbers with leading zeros so the visible format is always A-XXX-XXX-XXX.
Where to find your alien number
- I-797 Notice of Action - top right of the form, labeled 'A#' or 'Alien Registration Number'.
- EAD card - front of the card, lower-left area, labeled 'USCIS#' (the same number with no 'A' prefix).
- Green card (permanent resident card) - back of the card, labeled 'USCIS#'. Newer cards show it on the front.
- Immigration court documents - every NTA (Notice to Appear) and court notice prints it at the top.
- Visa stamp in your passport - printed in the annotation field for immigrant visas.
Alien number vs USCIS number vs receipt number
These get confused often, so here is the distinction:
- A-number / Alien number - your permanent ID. Starts with 'A'. 8 or 9 digits. Format: A-XXX-XXX-XXX.
- USCIS number - exactly the same as your A-number, just without the 'A' prefix. USCIS started using 'USCIS#' on newer documents.
- Receipt number - application-specific tracking number. 13 characters starting with EAC/WAC/LIN/SRC/NBC/IOE. Changes every petition you file.
Do all immigrants have an alien number?
Almost all. USCIS assigns an A-number the first time you file a petition that requires one - most commonly I-130, I-140, I-485, I-589 (asylum), or when you receive an EAD. Tourists on B1/B2 and people on simple non-immigrant visas (H-1B, F-1, L-1) without a pending green card application typically do not have an A-number until they file something more substantial.
What if you lost your alien number?
You cannot 'reset' it - it is permanent. Pull any prior I-797 notice, your EAD or green card, or your I-94 record. If you have none of those, file Form G-639 (FOIA request) with USCIS to retrieve your immigration file. Processing for G-639 takes 3-12 months, so use it only as a last resort.
Is the alien number the same as the green card number?
No. The green card number (also called card number or USCIS#) on the front of the green card is the 13-character code that identifies the physical card. Your A-number is your permanent ID. The card number changes when you renew or replace the card; the A-number does not.