A Number: Same File, Seen From the Other Side

An A-Number, or Alien Registration Number, is a unique seven-, eight- or nine-digit identifier that the Department of Homeland Security assigns to a noncitizen, as the USCIS glossary defines it. It names the person and the immigration file. A USCIS receipt number is a separate 13-character identifier, three letters plus 10 numbers, that names one application or petition. Case Status Online requires that receipt number. An A-Number typed there will not retrieve the case.

I spent more than a decade turning Marseille treatment-plant shift logs into household water reporting. The plant keeps one file number for a source. Each filter run gets its own ticket. From the kitchen they look like “a number” on a slip. USCIS splits the same way. I still keep my mother’s clear glass kettle, because scale, bubbles, and cloudiness look interchangeable until the water stands. People search “USCIS check” with the file number and then wonder why the window stays blank.

What is an A-Number on a USCIS form?

An A-Number is the Alien Registration Number, also called the Alien Number or A#. The USCIS glossary calls it a unique seven-, eight- or nine-digit number that DHS assigned to an alien.

That field wants the identifier of the person. The filing has its own number. The myUSCIS Annual Asylum Fee questionnaire calls the A-Number an immigration file number, 7 to 9 digits beginning with “A,” found on correspondence or cards from DHS or USCIS, or on immigration court records.

The USCIS Number is those same digits without the letter A. The Handbook for Employers (M-274), section 3.0, tells employees who attest as lawful permanent residents to enter their seven- to nine-digit A-Number or USCIS Number, and states that the USCIS Number is the A-Number without the “A” prefix. After May 10, 2010, the USCIS glossary lists that 9-digit USCIS Number on the front of Permanent Resident Cards (Form I-551).

How many digits is an A-Number?

The USCIS glossary length is seven, eight, or nine digits. Form I-9 instructions, edition 01/20/25, tell a lawful permanent resident to enter a 7- to 9-digit USCIS Number (A-Number). An employee who selects “an alien authorized to work” may enter those 7 to 9 digits as one of three options.

Shorter numbers are older files. Current screens want nine places. The Immigrant Fee page on USCIS.gov says an A-Number is the letter “A” followed by 8 or 9 numbers; if yours has fewer than 9 digits, insert a zero after the “A”: A12345678 becomes A012345678. The myUSCIS asylum-fee questionnaire adds zeros after the “A” until there are nine, for example A-001234567.

Immigration court uses that padded length. A July 18, 2008 EOIR news release required 9-digit A-Numbers on filings and on the automated phone system effective July 21, 2008, with a leading zero on eight-digit numbers. The EOIR Policy Manual, Part I, Chapter 1.5, still says A-Numbers have nine digits. I have not sat a lockbox shift at USCIS. A leading zero is a filler, not a new identity.

The SAVE tutorial (revised March 2024) tells benefit agencies the number ranges from six to nine digits and that leading zeros must fill nine places, without the letter A. The public glossary and Form I-9 still start at seven.

Where do I find my A-Number?

Look for USCIS#, A#, Alien #, or Registration Number. Count the digits after the A. Three letters followed by a long numeric string is the wrong line.

On a Permanent Resident Card issued after May 10, 2010, the USCIS glossary puts the 9-digit USCIS Number on the front. M-274 section 13.1 shows that number on the face of current cards, and on the back of the May 2010 design as well.

On an Employment Authorization Document (Form I-766), M-274 13.1 lists the USCIS number on the face. SAVE’s tutorial puts card numbers, also called document numbers, on the back of Form I-551 and on both sides of Form I-766.

On Form I-797, Notice of Action, the A-Number often sits near the top, labeled A# or USCIS#, beside a separate Receipt Number. Take the short digit string.

If you entered as an immigrant, the Immigrant Fee tips page points to the immigrant data summary, the USCIS Immigrant Fee handout, or the visa stamp. On the foil, the A-Number is the Registration Number. Pad it to nine digits the same way. Court paper is the other window: EOIR’s Automated Case Information System asks for the A-Number, and a Notice to Appear prints it.

How does an A-Number compare with a USCIS receipt number?

An A-Number identifies you. A receipt number identifies one filing. The USCIS glossary on Receipt Number calls it a unique 13-character identifier the agency provides for each application or petition it receives. It consists of 3 letters, such as EAC, WAC, LIN, SRC, NBC, MSC or IOE, with 10 numbers, found on notices of action USCIS has sent you.

Checking Your Case Status Online, on USCIS.gov, says you have to have that receipt number. The tool tells you to omit dashes. You may include asterisks if they appear on the notice as part of the receipt.

You keep one A-Number across filings. You receive a new receipt number every time USCIS accepts a form.

The mix-up behind “USCIS check” searches is the kitchen-side reading: both strings sit on the same notice, so either should open the case. The receipt is the batch ticket.

| Property | A-Number | Receipt number | Card document number | I-94 admission number | |---|---|---|---|---| | What it identifies | The person and the DHS file | One USCIS application or petition | The physical card (SAVE) | One CBP admission | | Official length | 7, 8, or 9 digits (USCIS glossary) | 13 characters: 3 letters + 10 numbers | SAVE: 13 characters (3 letters + 10 numbers) on the back of Form I-551 | 11 characters (CBP); Form I-9 still says 11 digits | | Where it lives | Front of cards after May 10, 2010 as USCIS# | Top of Form I-797 | Back of Form I-551 (SAVE) | Form I-94 / I-94 website | | Does it change? | No | Yes, each filing | Yes, when the card is replaced | Yes, each admission | | Case Status Online | Will not retrieve the case | Required | Will not retrieve the case | Will not retrieve the case |

I would rather leave the Case Status box empty until I have the labeled receipt than paste the A-Number. The system will not translate it.

What is the card document number, the I-94 number, and the dates on a green card?

The card document number belongs to the plastic. SAVE’s tutorial lists “Card / I-797 Receipt Number” as a unique 13-character identifier of three letters followed by 10 numbers, and says card numbers, also called document numbers, print on the back of Form I-551. Receipt numbers print on the top left of Form I-797. Same shape, different object. A replacement card gets a new document number. Your A-Number stays.

The I-94 admission number belongs to one entry. CBP’s Arrival/Departure Forms: I-94 page states that I-94 numbers were 11 digits, numeric only, and that beginning in May 2019 they remain 11 characters: nine digits, a letter in the 10th position, a digit in the 11th. Unexpired numeric I-94s stay valid until the Admit Until Date. SAVE calls it an 11-character identifier that may contain only numbers, or numbers and letters. Form I-9 instructions, edition 01/20/25, still say “11 digits.” If yours has a letter in the tenth place, enter the 11 characters CBP issued.

The green-card issue date that changes how you read the face is May 10, 2010. From that date forward, the USCIS glossary puts a unique 9-digit USCIS Number on the front of Form I-551. M-274 13.1 dates the green redesign to May 2010, a later design to May 1, 2017, and the current design to January 30, 2023. USCIS’s history of the card notes that Form I-551 (1989) was the first Green Card with an expiration date.

“Card Expires” is the document date. Lawful permanent residence does not end when the plastic does. The USCIS glossary says some cards contain no expiration date, most are valid for 10 years, and cards held with conditional permanent resident status are valid for 2 years. E-Verify’s glossary uses the same figures. If you filed Form I-90 to renew, USCIS’s Replace Your Green Card page (reviewed September 12, 2025) says the receipt notice plus the expired card is evidence of status for 36 months from the expiration date on the Permanent Resident Card. I-9 Central’s October 28, 2024 note treats that combination as List A for those same 36 months.

The form-expiration date on Form I-9 itself is 05/31/2027. The USCIS I-9 page lists edition date 01/20/25 at the bottom, expiration at the top. Employers may still use an 08/01/23 edition valid until 05/31/2027, and an 08/01/23 edition valid until 07/31/2026. Electronic systems must update to the 05/31/2027 version by 07/31/2026. Edition dates are mm/dd/yy. Expiration dates are mm/dd/yyyy.

Why does a USCIS case-status check reject my A-Number?

Because Case Status Online is built for the receipt. Checking Your Case Status Online says you have to have your case receipt number. The Contact Center page, last reviewed April 20, 2026, sends people who ask about case status to that tool or a USCIS online account. Live agents at 800-375-5283 will point you there too.

An A-Number is the right key for a different door. EOIR’s Automated Case Information System and the hotline at 1-800-898-7180 take the A-Number, nine digits, no letter A. That window shows immigration court and Board information. It will not show a pending I-485 or I-90 in USCIS’s queue.

If you filed Form I-90, USCIS tells you to wait 72 hours after filing before checking case status, and to have your receipt number and A-Number ready if you call. Both numbers matter. They do not substitute for each other.

Lost the I-797? Look in a USCIS online account or an attorney file. There is no conversion from an A-Number into 13 characters. You cannot reconstruct a filter-run ticket from the plant’s source ID. You go get the ticket.

What does Form I-9 want for an A-Number?

Section 1 wants the person. Section 2 wants the document the employer examined.

If you check “A lawful permanent resident,” the Form I-9 instructions (01/20/25) tell you to enter your 7- to 9-digit USCIS Number (A-Number). M-274 3.0 says the same, and reminds employers they may not ask for documents to verify what you typed in Section 1.

If you check “An alien authorized to work,” you enter the date employment authorization expires, if any, or N/A if it does not expire, then one of three identifiers: USCIS Number/A-Number (7 to 9 digits); Form I-94 Admission Number (11 digits on the instruction sheet); or foreign passport number and country of issuance.

The employer’s Section 2 records document title, issuing authority, document number, and expiration date, if any. On a Permanent Resident Card, that document number is the card number from the back, not the USCIS# from the front. Mixing those fields puts a string that belongs to plastic into a field that belongs to a person.

Form I-9’s own clock is the OMB date at the top of the current instructions: Expires 05/31/2027. That date does not change your A-Number. It tells the employer which blank is still in force.

Frequently asked questions

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

Yes. The Handbook for Employers (M-274), section 3.0, states that the USCIS Number is the same as the A-Number without the “A” prefix. On Permanent Resident Cards issued after May 10, 2010, the USCIS glossary lists that unique 9-digit number on the front as USCIS Number. Enter the digits. Do not treat the two labels as two files.

Can I check my USCIS case with my A-Number?

No. Checking Your Case Status Online requires the 13-character receipt number, three letters followed by 10 numbers, printed on Form I-797. The A-Number identifies you. The receipt identifies that filing. Immigration court’s Automated Case Information System is the public window that takes an A-Number.

How many digits is my A-Number?

The USCIS glossary defines it as seven, eight, or nine digits. Form I-9 instructions, edition 01/20/25, say to enter a 7- to 9-digit USCIS Number (A-Number). If yours is shorter than nine, the Immigrant Fee page and myUSCIS tell you to add zeros after the A until nine digits are filled.

Where is the A-Number on a green card?

On cards issued after May 10, 2010, read the front field labeled USCIS#. The USCIS glossary defines that as a unique 9-digit number. Older cards may show A#. The 13-character string SAVE describes on the back is the card document number, which identifies the plastic, not you.

What is the difference between an A-Number and a receipt number?

An A-Number is DHS’s 7- to 9-digit identifier for you and your file. A receipt number is USCIS’s 13-character identifier for one application or petition, three letters plus 10 numbers, on Form I-797. You keep one A-Number. You receive a new receipt number each time USCIS accepts a filing.

Do I put my A-Number or the card number on Form I-9?

Section 1 wants the 7- to 9-digit A-Number or USCIS Number if you attest as a lawful permanent resident. Section 2 records the document number from the card the employer examined, which SAVE places on the back of Form I-551. Those are different fields. Swapping them sends the card’s ID into the person’s slot.

Why does my A-Number have fewer than nine digits?

Older files used seven or eight digits, and the USCIS glossary still allows seven, eight, or nine. EOIR has required nine digits since July 21, 2008, with a leading zero on eight-digit numbers. myUSCIS pads the same way. The extra zeros are fillers. They are not a new A-Number.