What is an A-number?

What an A-number is

An A-number is the identification number immigration assigns to a person. It is the letter A followed by nine digits, written like A123456789. Immigration uses it the way a court uses a case number: it follows the person through every system, even when their name is spelled four different ways across four documents.

It is assigned by the government, not chosen. A person who has ever applied for immigration benefits, been placed in removal proceedings, or been detained will have one.

Where to find it

It appears on most immigration paperwork the family already has at home. Look on a permanent resident card, an employment authorization document, a notice to appear, any letter from immigration court, or the receipt for any application filed with immigration.

If someone has been detained, the paperwork they were given at the time will carry it. So will anything their attorney has filed.

What if you do not have it?

You can still search. The ICE Online Detainee Locator accepts a full name, country of birth, and date of birth instead. It is less reliable, because it depends on the name being entered the same way you type it, but it works often enough to be worth trying first.

Spell the name exactly as a government office would have entered it. Try both surnames, and try them in each order. If nothing comes back, call us with what you do have. Working without an A-number is ordinary for us.

Keep it written down

Once you have the A-number, write it somewhere you will not lose it. Every call you make from that point, to the facility, to the court, to a bond company, will start with someone asking for it, and having it ready turns a twenty minute call into a five minute one.

Checked against ICE guidance on 30 July 2026. This is general information, not legal advice.