Alien Registration Number: What It Is And Where To Find It

If you have ever filed anything with USCIS, you already have a number that will follow you for the rest of your life. Your alien registration number, usually called the A-number, is the identifier that links every petition, approval, and card in your file back to you.

It carries real weight right now. When the government rolled out its registration rule in 2025, it estimated that roughly 1.4 million people a year would go through the new process.

This guide covers what the number is, who gets one, where it appears on each of your immigration documents, how to recover it if your paperwork is gone, and how it differs from the other numbers on your cards.

What is an alien registration number?

An alien registration number is a unique 7-, 8-, or 9-digit identifier that the Department of Homeland Security (DHS) assigns to you if you are a noncitizen with a record in the U.S. immigration system. You will see it written with an "A" in front, as in A-123456789.

It is also called an alien number or an A-number, and all three terms mean the same thing.

Think of it as the account number for your immigration history. Every application you file, every notice you receive, and every card you are issued is filed against that one identifier, and behind it sits your A-File.

Three agencies rely on it: USCIS (U.S. Citizenship and Immigration Services) for benefits, U.S. Customs and Border Protection for entries and admissions, and ICE for enforcement. Because all three pull from the same identifier, it is how the government confirms that the person filing a green card application in 2026 is the person who filed in 2019.

One clarification worth making early, because it trips people up: there is no such thing as an alien registration card. The number lives on your documents, not on a card of its own.

Who gets an alien registration number?

You do not need one to be in the United States legally, and plenty of people in valid status have never been assigned one. Whether you have one depends on what you have filed and what status you hold, not on how long you have been here.

You almost certainly have one if you fall into any of these groups:

Lawful permanent residents: Every green card carries one, and yours was assigned during the immigrant petition or adjustment of status process that got you the card.
Applicants for permanent residence: Filing Form I-485 to adjust status, or going through consular processing abroad, triggers the assignment if you do not already have one.
Work permit holders: If you applied for and received an employment authorization document, you were given one as part of that process.
Refugees and asylees: A grant of asylum, or admission as a refugee, comes with one attached to your protection record.
Holders of temporary protected status and DACA: Both TPS and Deferred Action for Childhood Arrivals recipients receive one, largely because both come with work authorization.
Anyone in removal proceedings: If the government has placed you in immigration court, your number appears on every filing and every notice in the case.

Who typically does not have one

You generally will not have one if your only contact with the system has been a temporary visa and a border inspection. Tourists, business visitors, and most students on an F-1 visa fall into this category, at least at first.

The distinction is not the visa category itself. It is whether a benefit application, a protection claim, or an enforcement action has opened a file in your name. An F-1 student who later applies for Optional Practical Training gets one with the EAD.

When the number gets assigned

Your number is created the first time the system opens a file on you, which is earlier than most people expect. If you are adjusting status inside the United States, it usually appears on the receipt notice that arrives after you file.

If you are going through consular processing, you will typically see it at or shortly after your consular interview.

For employment-based cases, it often shows up before you have any status at all. When your employer files an I-140 immigrant petition for you, USCIS assigns a beneficiary number that appears on the notice of action, years before you touch a green card.

Alien registration number format: what the number looks like

Your number is short, and its format is more forgiving than it looks. The letter "A" is followed by the digits, and you may see it printed with hyphens or spaces, as in A-123-456-789 or A 123 456 789. Those are all the same number.

How many digits is an alien registration number?

Your number will have 7, 8, or 9 digits after the "A," depending on when it was issued. Nine digits has been standard for years, so a shorter one simply means it was assigned some time ago, not that something is wrong.

Most USCIS forms and online systems expect 9 digits. When yours is shorter, pad it with zeros immediately after the "A" until you reach 9, so that A-1234567 becomes A-001234567. The zeros are formatting, and adding them does not change your identity in the system.

How to enter it correctly on forms

You will be asked for this number on nearly every immigration form you touch, and small entry errors create real delays. A few rules keep you out of trouble:

Match the field: Some forms print the "A" for you and want only the digits. Others want the full string. Read the label before you type.
Add leading zeros when the field requires 9 digits: Do not leave boxes blank and do not drop digits to make yours fit.
Drop the hyphens unless asked: Online systems generally want digits only.
Use the same number every time: Consistency is what keeps your records attached to one file instead of splitting them across two.
Never guess: If you cannot find it, leave the field blank or enter "N/A." A wrong entry is harder to unwind than a missing one.

Where to find alien registration number details on each document

Your number is printed on your immigration documents, but the label changes depending on which one you are holding. On some it reads "USCIS#," on others "Alien #," and on others "Registration Number." All three point to the same digits.

Alien registration number on green card (Form I-551)

Look at the front of your permanent resident card, in the data block near your photo. On every card issued after May 2010, it sits under the label "USCIS#," without the "A" prefix. Older cards may label the same field "A#" instead.

The number also appears on the back of the card, inside the machine-readable zone. Important note: The 13-character string on the back is your card's document number, not your A-number. Before you copy anything off the back of your green card onto a form, confirm which field you are reading.

Alien registration number on EAD (Form I-766)

Check the front of the card, where the layout mirrors the green card almost exactly. Your number appears under "USCIS#," in the same 7-to-9-digit format.

If you have renewed your EAD card more than once, compare across cards. They should match every time, because the card changes and the number does not. A mismatch is worth raising with USCIS rather than ignoring.

Alien registration number on immigrant visa or visa stamp

Pull out the passport you used to enter the United States and turn to the visa page. On an immigrant visa, your number is printed as "Registration Number," usually in the upper right of the visa stamp. If what you see is fewer than 9 digits, add the leading zero yourself when you transfer it to a form.

This applies only to immigrant visas. A nonimmigrant visa foil, whether H-1B, E-3, or B-1/B-2, does not carry the number, because the State Department issues those under different identifiers.

Alien registration number on I-797 notices

Search the top of any Form I-797 that USCIS has sent you. On most versions, including receipt notices, approval notices, and biometrics appointment notices, your number appears near the top of the page, labeled "A#" or "USCIS#," close to the receipt number.

Not every version includes it, so if the first notice comes up empty, work through the rest of your file. An approval notice from an I-140 or I-485 is the most reliable place to look.

Quick reference: where the number appears

The table below maps each document to the field label you are looking for and the exact spot on the page.

How to find alien registration number without documents

If your cards and notices are gone, you have not lost the number itself. It lives in government systems, and you have several ways to get it back. Work through these in order: the first two are free and fast, and the last is neither.

Check your USCIS online account: Log in at the myUSCIS portal and open any linked case. Your details and any electronic notices stored in the account will show it. If you filed online at any point, this takes about 2 minutes.
Call the USCIS Contact Center: The number is 800-375-5283. You will need to verify your identity with your date of birth, country of birth, and details of a prior filing, so have that information ready before you call.
Contact a prior immigration attorney: If an immigration lawyer ever filed anything on your behalf, it is in their case file, and a records request usually costs nothing.
Schedule an in-person appointment: Request one at a USCIS field office through the Contact Center. This makes sense when you need the number verified against your identity documents rather than simply looked up.
File a FOIA request: Submit Form G-639 to request your immigration records under the Freedom of Information Act. This returns your full A-File, and processing runs from several weeks to well over a year.

What to do if the number looks wrong

If what appears on one document does not match another, do not pick one and move on. Mismatches usually mean a data entry error, but occasionally they mean you were assigned two numbers, which happens when a second file is opened under a variant of your name.

Report it to USCIS in writing, with copies of every document showing each version, and ask for the records to be consolidated. Two open files in your name is the kind of problem that surfaces years later, at your citizenship interview, when the government cannot reconcile your history.

How your A-number compares to USCIS and receipt numbers

These two comparisons account for most of the confusion you are likely to run into, and they have very different answers. One pair describes the same thing twice; the other describes two genuinely different things.

Alien registration number vs USCIS number: are they the same?

Yes. Your USCIS number is your A-number with the "A" removed. If yours is A-123456789, then 123456789 is what belongs in that field, and both are correct answers to the same question.

The confusion is a labeling artifact. When the card designs were updated in 2010, the field that used to read "Alien #" was relabeled, and both terms stayed in circulation. Either format is accepted on USCIS forms.

A-number vs receipt number

These are not the same, and treating them as interchangeable will get your filing rejected. Yours identifies you. A receipt number identifies one specific application.

You can spot the difference at a glance. Receipt numbers are 13 characters and open with three letters naming the service center handling the case, as in WAC2412345678. Yours is digits only, preceded by an "A." When USCIS asks for your USCIS case number, they want the 13-character string.

Can you have more than one case number?

You will accumulate case numbers over time, and that is normal. Each petition, renewal, and new application generates its own USCIS case number, so someone who filed an I-140, an I-485, and an I-765 has three.

Your A-number does not multiply the same way. One person, one number, no matter how many cases sit underneath it. If you find yourself with two, that is an error to correct.

How it compares to the other numbers on your documents

You are carrying several identifiers at once, and they are easy to mix up because they sit inches apart on the same cards. The table below sorts them out.

Identifier	Who issues it	What it identifies	Format
A-number	Department of Homeland Security (DHS)	You, permanently, across the immigration system	A + 7 to 9 digits
Social Security number	Social Security Administration	You, for tax and benefit purposes	9 digits (XXX-XX-XXXX)
I-94 admission number	U.S. Customs and Border Protection (CBP)	One specific entry or admission	11 digits
Green card number	USCIS	One physical permanent resident card	13 characters, printed on the back
USCIS online account number	USCIS	Your online account, not your immigration file	12 digits

Two of these deserve a closer look. Your social security number and your A-number are entirely separate: the SSN comes from the Social Security Administration and covers wages, taxes, and benefits, while the other tracks your immigration records. Neither substitutes for the other.

Your green card number is the one most often mistaken for it. It changes every time a new card is printed, which is exactly what your A-number does not do. If something on your card changed when you renewed, it was not your A-number.

Where the A-number goes on Form I-9

If you are starting a new job, you will meet this number again on Form I-9, Employment Eligibility Verification. The form asks for it in two places, and who fills in each one matters.

Section 1, which you complete on or before your first day: If you attest to being a lawful permanent resident or an alien authorized to work, you enter your A-number in the field provided, in either format. If your authorization comes from a Form I-94 rather than a USCIS document, you may enter the I-94 number instead.

Section 2, which your employer completes within 3 business days of your start date: Your employer records the document number from whatever you presented, along with its expiration date. When you present a green card or an EAD, the number on the front and the document number are different fields, and employers regularly conflate them.

If you do not have an A-number, leave the field blank or enter "N/A" rather than borrowing something from another document. E-Verify runs off what your employer enters, so a fabricated entry creates a tentative nonconfirmation that takes real time to clear.

When you actually need it

You will be asked for this number more often than you expect, and usually at moments when your documents are not in front of you. Keeping it somewhere accessible is worth the 2 minutes it takes.

Expect to need it for:

New filings: Every USCIS form with a field for it, including the I-485, the I-765, the I-131, and the N-400, uses it to attach the filing to your existing file.
Case status checks: Some USCIS online tools key off it rather than your USCIS case number.
Employment verification: Form I-9 and E-Verify both use it whenever a USCIS document is what lets you work.
Naturalization: Your N-400 relies on it to connect your permanent residence history to your citizenship application, which is how USCIS confirms continuous residence.
Immigration court: Every filing and decision in removal proceedings is indexed to it.
Other agencies: State DMVs, universities verifying in-state tuition eligibility, and benefits offices sometimes ask for it.

The alien registration requirement and what it means in 2026

If you have been reading about registration in the news, you are looking at a separate legal duty that intersects with your number. The difference is worth understanding.

What the law requires

If you are a noncitizen aged 14 or over and you remain in the United States for 30 days or longer, federal law under INA 262 requires you to register and be fingerprinted. The requirement itself is decades old.

What changed is enforcement. After Executive Order 14159 in January 2025, an interim final rule took effect on April 11, 2025, creating Form G-325R as a way for people with no other registration path to comply.

Most people were already registered through a visa application, an I-94, or a prior USCIS filing, and did not need to do anything new.

How registration relates to your A-number

Registration and your A-number travel together but are not the same thing. When you register, the government creates or confirms a record for you, and the number is how that record is indexed. Registration itself does not grant status, work authorization, or any other immigration benefit.

What changed in 2026

Your obligations did not change much this year. A final rule published on June 29, 2026 adopted the 2025 interim rule and updated the list of forms and processes that satisfy the requirement. People who still need to register continue to use Form G-325R, and comments on further changes to the registration and fingerprinting regulations are open through August 28, 2026.

Important note: Failing to register when required carries criminal penalties, and you have an ongoing obligation to carry your registration document if you are 18 or older.

If you are unsure whether you already complied, run your situation through the USCIS alien registration requirement page before filing anything. Most people already in the system do not need the G-325R at all.

How to protect your A-number

Treat this number the way you treat your SSN, because it opens the same kind of door. It is the key to your immigration file, and it is printed on documents you carry with you.

It is sensitive for a specific reason: someone who has it plus a few biographic details can attempt to access your records or make a fraud attempt look legitimate. That risk is small, and a few habits shrink it further:

Store copies deliberately: Keep scans of every card and notice in an encrypted folder or a password manager, not in your inbox or your camera roll.
Verify who is asking: Share it with USCIS, the immigration attorney representing you, or an employer completing your I-9. Nobody else has a routine need for it.
Never respond to unsolicited requests: USCIS does not call or email asking you to confirm it. If contact you did not initiate asks for it, do not answer.
Watch what you post: Photos of green cards and approval notices circulate widely on social media, and the digits are legible in almost all of them.

If you suspect misuse, report it to USCIS and to the FTC identity theft portal, and ask USCIS to note the report in your file so that unexpected activity gets flagged rather than processed.

Does your A-number expire or change?

Your number does not expire, and in almost every case it does not change. Cards expire; the digits printed on them do not.

It follows you across status changes, renewals, and category shifts. Someone who arrives as a student, gets an EAD, adjusts status through employment, and files for citizenship 15 years later carries the same one the whole way. That permanence is the point: it lets USCIS see a single continuous history instead of unconnected filings.

There are narrow exceptions. A second number is occasionally issued by mistake, usually through a name variation or a duplicate file, and the fix is consolidation rather than choosing one.

After you naturalize, your number is not revoked. It stays attached to your historical record and appears on your certificate, though you will rarely need it again once you are a citizen, aside from petitioning for relatives.

The bottom line

Your A-number is the one identifier in the immigration system that never changes, which makes it worth knowing by heart and worth guarding carefully. Find it once, store it somewhere you can reach without digging through a filing cabinet, and use the same digits consistently on every form you file.

How Lighthouse helps with the filings your A-number appears on

Your number is only as useful as the case attached to it, and the filings it appears on decide whether you can work, stay, or become a permanent resident. Getting those right is the part that takes real work.

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Frequently asked questions on the alien registration number

Where can I find my A-number?

Check the front of your green card or EAD under the label "USCIS#" first. If you have neither, look at the top of any I-797 notice USCIS has sent you, the "Registration Number" field on your immigrant visa, or your myUSCIS account.

Is my A-number the same as an SSN?

No. Yours is issued by the Department of Homeland Security and identifies your immigration file. Your social security number comes from the Social Security Administration and covers wages, taxes, and benefits. They serve different purposes, and many people hold both.

Who has an A-number?

Permanent residents, green card applicants, work permit holders, refugees, people granted asylum, TPS and DACA recipients, and anyone in immigration court. If your only contact with the system has been a temporary visa and a border inspection, you probably do not have one.

Are my A-number and I-94 number the same?

No. Your I-94 admission number is an 11-digit number tied to a specific entry into the country, and you can have many of them. Yours is permanent and identifies you rather than any single admission.

What is an A-number, in one sentence?

It is a 7- to 9-digit number preceded by "A" that the government assigns to noncitizens to index their immigration records across USCIS, CBP, and ICE.

How do I find my number if I lost my card?

Log into your USCIS online account, call the USCIS Contact Center at 800-375-5283, or ask any attorney who has represented you. If none of those work, file Form G-639 to request your file under FOIA.

Is my A-number the same as my USCIS number?

Yes. The two are the same identifier, written differently. A-123456789 and 123456789 both point to the same file, and both are accepted on immigration forms.