A Permanent Resident Card (Form I-551, commonly called a green card) has multiple identification numbers on it, and each one goes in a different place on Form I-9. The most common mistake employers make when completing Section 2 is entering the wrong number — specifically, writing the Alien Registration Number (A-Number) from the front of the card in the Document Number field, when the actual document number is a different 13-character code on the back.
This guide explains where to find each number on the card, which Form I-9 field it belongs in, and how to avoid the errors that show up most often in I-9 audits. If your new hire just handed you a green card and you are staring at the I-9 form wondering which number goes where, you are in the right place.
A U.S. Permanent Resident Card (Form I-551) contains three distinct identification numbers. Each one serves a different purpose, and each one goes in a different place on Form I-9. Getting them mixed up is one of the most frequent I-9 errors found during audits.
| Number | Where on the Card | Where on Form I-9 |
|---|---|---|
| A-Number (Alien Registration Number) | Front of the card — 7- to 9-digit number starting with "A" | Section 1 — entered by the employee under "USCIS A-Number" |
| USCIS Number | Same as the A-Number, but without the "A" prefix | Section 1 — same field, just a different format |
| Document Number | Back of the card — 13-character alphanumeric code | Section 2 — entered by the employer in the "Document Number" field |
The critical distinction: The A-Number identifies the person. The Document Number identifies the physical card. They are different numbers, printed on different sides of the card, and they go in different sections of Form I-9.
The front of the Permanent Resident Card shows the cardholder's photo, name, date of birth, country of birth, and the USCIS Number (also called the Alien Registration Number or A-Number). On current card designs, the USCIS Number appears as a 9-digit number prefixed with "A" — for example, A-123456789.
This number belongs to the person, not the card. It stays the same even if the card is replaced, renewed, or reissued. The employee enters this number in Section 1 of Form I-9 when they select "A lawful permanent resident" as their citizenship/immigration status.
The back of the Permanent Resident Card contains the Document Number — an alphanumeric code (on current card designs, 13 characters) that uniquely identifies that specific physical card. This number changes every time a new card is issued (renewal, replacement, or updated conditions).
The Document Number is what the employer enters in Section 2 of Form I-9, in the "Document Number" field under List A. It is not the same as the A-Number on the front.
A Permanent Resident Card (Form I-551) is a List A document, which means it establishes both identity and employment authorization on its own. When an employee presents a green card, you complete only the List A column in Section 2 — do not ask for any List B or List C documents.
Here is exactly what to enter in each Section 2 field:
| Section 2 Field | What to Enter |
|---|---|
| Document Title | "Permanent Resident Card" or "Form I-551" |
| Issuing Authority | "USCIS" or "U.S. Citizenship and Immigration Services" |
| Document Number | The 13-character alphanumeric code from the back of the card |
| Expiration Date | The "Card Expires" date from the front of the card |
For a full reference on issuing authorities for all I-9 documents, see our Issuing Authority on I-9 guide.
Not sure you are recording a permanent resident card correctly? Our compliance team has 27+ years of I-9 and E-Verify expertise. We review documents, answer questions, and walk you through Section 2 — including remote verification via video call for distributed teams. Schedule a free compliance call.
This is the single most common error. The employer sees the 9-digit A-Number on the front of the card and writes it in the Document Number field in Section 2. But Section 2 requires the 13-character Document Number from the back of the card. The A-Number belongs in Section 1 — and the employee fills that in, not the employer.
How to tell them apart: If the number starts with "A" and has 7 to 9 digits, it is the A-Number (Section 1). If it is a 13-character alphanumeric code, it is the Document Number (Section 2).
The USCIS Number is the same as the A-Number but without the "A" prefix. So if the A-Number is A-123456789, the USCIS Number is 123456789. Both refer to the same identifier — the person's Alien Registration Number. Neither one is the Document Number. The Document Number is a separate 13-character code on the back of the card.
A Permanent Resident Card is a List A document. It satisfies both the identity and employment authorization requirements by itself. If an employee presents a valid green card, do not ask for a driver's license, Social Security card, or any other document. Requesting additional documents when a valid List A document has been presented may constitute document abuse under the anti-discrimination provisions of the Immigration and Nationality Act (INA Section 274B).
Permanent resident status does not expire when the physical card does. A lawful permanent resident with an expired card is still authorized to work in the United States. You must accept an expired Permanent Resident Card for Form I-9 purposes, and you may never reverify an employee who initially presented a Form I-551. This is one of the most misunderstood rules in I-9 compliance. For the full explanation, see our Form I-551 Permanent Resident Card Guide.
An I-551 stamp (also called an ADIT stamp) in a passport or on a Form I-94 is a valid List A document for Form I-9. Lawful permanent residents who do not yet have their physical card — or whose card is being renewed — may present this stamp. It is valid until the expiration date on the stamp, or for one year from the date of issuance if no expiration date is shown.
If your company participates in E-Verify, there are additional steps when an employee presents a Permanent Resident Card.
When creating an E-Verify case, you will enter the employee's A-Number or USCIS Number from the front of the card — not the Document Number from the back. If the employee entered their A-Number in Section 1 correctly, you will use that same number when submitting the E-Verify case.
Photo match: E-Verify will return a photo for employees who present a Permanent Resident Card. You must compare the photo E-Verify displays to the photo on the physical card the employee presented, and to the employee standing in front of you. This is a required step — not optional.
For more on how E-Verify works with I-9, see our E-Verify integration overview.
There are two numbers on a Permanent Resident Card that are relevant to Form I-9. The A-Number (Alien Registration Number) from the front of the card goes in Section 1, entered by the employee. The Document Number — a 13-character alphanumeric code from the back of the card — goes in Section 2, entered by the employer. The Document Number is what most people mean when they ask about the "green card number for I-9."
The Document Number is on the back of the Permanent Resident Card. On current card designs, it is a 13-character alphanumeric code. Do not confuse it with the A-Number on the front of the card, which is a 7- to 9-digit number starting with "A." The Document Number is what goes in the Section 2 Document Number field on Form I-9.
Yes. The USCIS Number and the Alien Registration Number (A-Number) refer to the same identifier. The only difference is formatting: the A-Number includes the "A" prefix (e.g., A-123456789), while the USCIS Number drops the prefix (e.g., 123456789). Both go in Section 1 of Form I-9. Neither one is the Document Number that goes in Section 2.
No. You may never reverify a lawful permanent resident who presented a Permanent Resident Card (Form I-551). Permanent resident status does not expire, even if the physical card does. Reverifying an employee because their green card expired may constitute citizenship status discrimination under the INA.
Yes. An expired Permanent Resident Card is still an acceptable List A document for Form I-9. The card's expiration date does not affect the person's work authorization or immigration status. You must accept it and should not ask for a different or additional document.
If you have questions about recording a Permanent Resident Card on Form I-9, our compliance team is here. We have handled hundreds of thousands of I-9s and know exactly how to resolve document questions quickly.
Call us at (713) 668-6200 (Mon–Fri, 8 AM – 5 PM CT), email support@i-9intelligence.com, or submit a ticket.
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This article reflects USCIS guidance current as of March 2026. Form I-9 procedures and document requirements may change. Check uscis.gov/i-9 and the USCIS Handbook for Employers (M-274) for the latest updates. This article is for informational purposes only and does not constitute legal advice. Consult qualified legal counsel for guidance specific to your organization.
