An Alien Registration Number, also called an A-Number or alien number, identifies a person in U.S. immigration records. It usually contains seven to nine digits and may appear under labels such as "A#," "A-Number," "Registration Number," or "USCIS#."
Key Takeaways
- An A-Number is a person-specific immigration identifier, not an application tracking number.
- It usually has seven to nine digits and may include leading zeros when a system requires nine digits.
- On a green card or EAD, the number may be labeled "USCIS#."
- An immigrant visa placed in a passport may show the number as a "Registration Number."
- Not every tourist, student, temporary worker, or other nonimmigrant automatically receives one.
- An A-Number differs from a USCIS receipt number, green card document number, and Social Security number.
What Is an Alien Registration Number or Alien Number?
An A-Number is a unique identifier used by the Department of Homeland Security and its immigration agencies to connect a person with immigration records. USCIS commonly uses it when processing permanent residence, employment authorization, asylum, naturalization, and other immigration matters.
The number usually appears as seven, eight, or nine digits. A document may print it as "A123456789," "A# 123456789," or simply "123456789." The letter A is a label, not part of the numeric identifier. Labels vary by document type and issue date, so you should consider both the format and the location before deciding that a number is your A-Number.
Older A-Numbers may contain fewer than nine digits. A USCIS form or electronic system that requires nine digits may instruct you to add leading zeros. For example, a seven-digit number such as 1234567 could be entered as 001234567. Follow the instructions for the particular form or system. Do not independently remove digits or add zeros when copying the number onto a document that does not request a nine-digit format.
The A-Number generally remains associated with the person rather than a single application. A person may therefore have one A-Number but several receipt numbers from different filings. If you are applying for permanent residence, reviewing the broader green card process can help you understand when different identifiers and notices may appear.
How to Find an Alien Registration Number by Document
Start with the most recent original immigration document issued to you. Check the document's labeled fields rather than choosing the first nine-digit number you see. Cards and notices often contain several identifiers, and some have similar formats.
| Document | Possible label | Where to look | What to check |
|---|---|---|---|
| Permanent Resident Card, or green card | USCIS# or A# | On the front of newer cards; older designs may use a different label or placement | Do not confuse it with the Card# or document number |
| Immigrant visa in a passport | Registration Number | In the printed data fields on the immigrant visa foil | The passport number is separate |
| USCIS Notice of Action, including some Form I-797 versions | A-Number, A#, or a related applicant field | In the applicant or beneficiary information area, often in the upper portion when included | Not every notice version displays an A-Number |
| Employment Authorization Document | USCIS# | On the front of the card | Do not use the Card# as the A-Number |
On a newer green card, the "USCIS#" on the front is generally the A-Number. The card also has a separate document number, commonly labeled "Card#" on newer designs. If you need that identifier instead, see how to find your permanent resident card number.
Other immigration documents, including some travel documents, certificates, or case records, may also display an A-Number. Layouts change, so use the printed field label and compare the number across multiple USCIS-issued documents. An I-94 admission number is not automatically an A-Number and should not be treated as one merely because it is numeric.
Alien Registration Number on a Passport or Immigrant Visa
A passport itself does not receive an A-Number. The confusion arises because an immigrant visa placed inside a passport may display the visa holder's A-Number. On the immigrant visa foil, look for a field labeled "Registration Number." The number in that field is generally the A-Number.
This distinction matters because the passport's biographical page contains a passport number issued by the traveler's country. That passport number identifies the travel document. It does not serve as the person's U.S. immigration identifier. Other numbers on the visa, including visa-related control or case information, also serve different purposes.
If you completed immigrant visa processing outside the United States, review the visa foil in the passport used for entry. If you applied for permanent residence from inside the United States, you may not have an immigrant visa foil. In that situation, check USCIS notices, an EAD, or a permanent resident card instead.
A nonimmigrant visa for temporary travel, study, or work should not be assumed to contain an A-Number. Some temporary visa holders later receive an A-Number through a separate immigration process, but the number is not assigned to every passport or visa. If you are determining your eligibility for permanent residence rather than merely locating an identifier, review the applicable green card requirements.
Who Has an A-Number?
Lawful permanent residents have A-Numbers. USCIS may also assign them to people involved in other immigration processes, including certain applicants for adjustment of status, recipients of employment authorization documents, refugees, asylees, and people placed in removal proceedings. A child may have an A-Number, so age alone does not determine whether one exists.
Not every noncitizen automatically receives an A-Number. A tourist, international student, business visitor, or temporary worker may have a visa, passport, and I-94 but no A-Number. A person in one of these categories may later receive an A-Number after applying for a qualifying immigration benefit or becoming involved in another formal immigration process.
Likewise, being physically present in the United States without lawful status does not by itself establish that a person has an A-Number. The person may receive one through removal proceedings, an asylum claim, an application for immigration relief, or another interaction with immigration authorities. The relevant question is whether an agency assigned the identifier, not simply how the person entered or what status the person currently holds.
If you have never seen an A-Number on an official document, do not create one or borrow a family member's number. Family members usually have separate identifiers, including children listed in the same immigration matter. People considering family-based or employment-based residence can review typical green card process stages and timing to see when USCIS notices and identification numbers may be issued.
A-Number vs. USCIS Receipt Number, Card Number, and SSN
Several government identifiers can appear in the same file. Use the label, format, issuing agency, and stated purpose to distinguish them.
| Identifier | Primary purpose | Typical format | Issuer or source | Common location |
|---|---|---|---|---|
| A-Number | Identifies a person in immigration records | Seven to nine digits, sometimes preceded by A or A# | Department of Homeland Security immigration agencies | Green card, EAD, immigrant visa, or certain USCIS notices |
| USCIS receipt number | Tracks a particular petition or application | Three letters followed by ten numbers | USCIS | USCIS receipt and other case notices |
| Green card document number | Identifies the physical card | Often three letters followed by ten numbers | USCIS | On the permanent resident card, commonly as Card# on newer cards |
| Social Security number | Supports Social Security earnings records and other authorized identification uses | Nine digits | Social Security Administration | Social Security card and authorized employment or tax records |
A USCIS receipt number belongs to a case, not permanently to the person. Each new petition or application can receive a different receipt number. Its first three characters are letters, which helps distinguish it from an A-Number. An online account number, if USCIS assigns one, is another separate identifier and should only be entered when a form requests it.
An A-Number is also not a Social Security number. Both can contain nine digits, but they come from different agencies and serve different functions. Never substitute one for the other. Read the exact field name on the form and use only the requested identifier.
What to Do If Your A-Number Is Missing or Inconsistent
If you cannot find your A-Number, first gather your green card, EAD, immigrant visa, USCIS notices, travel documents, and copies of prior filings. List each number labeled "A-Number," "A#," "Registration Number," or "USCIS#." Then compare the digits across the documents. A shorter version and a nine-digit version with leading zeros may refer to the same identifier.
Do not assume that every USCIS notice must contain the number. Form I-797 is used for different types of notices, and the fields vary. One notice may display an A-Number while another only shows a receipt number. The absence of an A-Number on a particular notice does not necessarily mean you have never been assigned one.
If two documents show genuinely different numbers, check whether they belong to different family members. Also compare names, dates of birth, receipt numbers, and case types. A clerical error, a mismatched document, or records associated with another person requires more care than a simple difference in zero padding.
Use current USCIS contact or records-request procedures if your own documents do not resolve the issue. When a physical green card contains incorrect information or needs replacement, follow USCIS instructions for the reason involved. Replacement procedures and costs can change, so review current guidance and the applicable green card renewal and replacement information before filing.
If your documents show different A-Numbers, USCIS records appear linked incorrectly, or a filing deadline is approaching before you can confirm the identifier, an immigration attorney can review your record, identify the likely correct number, communicate with USCIS, and prepare or correct the affected filing. You can post your legal need on UpCounsel's marketplace to receive proposals from qualified lawyers, with responses typically arriving within a day.
How an A-Number Is Used and What It Does Not Prove
USCIS forms may ask for an A-Number so the agency can connect a new filing to the applicant's existing immigration record. The number can also appear in employment authorization, permanent residence, naturalization, travel, records requests, and immigration court matters. Enter it only in a field that specifically requests an A-Number or USCIS number used in that context.
The identifier does not independently prove current immigration status, employment authorization, or permission to travel. Those questions depend on valid documents, agency decisions, admission records, and the law applicable to the person's circumstances. An unexpired or expired card may display an A-Number, but the number itself does not establish that the card remains valid.
Having an A-Number also does not, by itself, answer whether a person has satisfied a federal alien registration requirement. An identifier and evidence of registration are related concepts, but they are not interchangeable. A person should review current USCIS alien registration instructions to determine which documents count as evidence and whether any action is required.
Protect the number as sensitive personal information. Share it when an authorized government form, employer process, attorney, or other legitimate recipient requires it. Avoid posting images of immigration documents publicly, since the image may expose an A-Number along with a name, photograph, date of birth, document number, and other identifying information.
Frequently Asked Questions
What Is an Alien Registration Number?
It is a numeric identifier connected to an individual's U.S. immigration file. The number helps agencies match later filings and decisions with an existing record even when the person changes addresses, replaces a document, or submits a new type of application.
What Is an Alien Number?
An alien number is another name for an A-Number. The terminology may differ across cards, notices, older records, and form instructions, but you should rely on the labeled field and matching digits rather than expecting every document to use identical wording.
How Do I Find My Alien Registration Number?
Review the clearest, most recent government-issued immigration document available to you. If the print is damaged or a copy is incomplete, compare it with prior filing copies or notices rather than trying to reconstruct unclear digits from memory.
What Is an A-Number in USCIS Records?
In USCIS records, an A-Number is the personal identifier used to associate immigration information with an individual. It is separate from a USCIS online account number, which relates to online account functions and should not be entered in an A-Number field.
Where Can I Find My A-Number on Form I-797?
Look in the applicant or beneficiary information fields if that version of Form I-797 includes an A-Number. Because USCIS issues several types of I-797 notices, use the field label rather than relying on a fixed corner or assuming the receipt number is the A-Number.
Is an Alien Number the Same as a USCIS Number?
It can be, but only when "USCIS#" labels the personal identifier on a document such as a green card or EAD. The phrase should not be confused with a USCIS receipt number or online account number, both of which serve different purposes.
Is an Alien Registration Number the Same as an SSN?
No, an A-Number and Social Security number are separate identifiers issued for different purposes. A person may have both, one, or neither, depending on the person's immigration and Social Security records. Similar digit counts do not make the numbers interchangeable.
