Where Is the Document Number on a Green Card

September 29, 2026

If a form asks for your green card document number, turn the Permanent Resident Card over. Look near the bottom, where you’ll see a long machine-readable string of letters and numbers. The document number appears in the first line of that string.

Don’t use the number on the front just because it’s easier to see. The document number is found on the back of the card.

Where the green card document number is located

The green card document number is on the back of the Permanent Resident Card.

Near the bottom, you’ll find a block of long lines made up of letters and numbers. This is the card’s machine-readable zone. It’s designed to hold card information in a standard format.

To find the document number:

Turn the card over.
Go to the bottom section with the long lines of characters.
Look at the first line.
Identify the document number within that line.

That first line is the key. If the form asks for the document number, start your search there rather than looking for the USCIS number or another nine-digit number.

The exact appearance can vary by card design. Your card may not look exactly like an example you find online. The back of the card and the first line of the machine-readable area are the most reliable clues.

How to identify the number in the machine-readable zone

The machine-readable zone can look like a confusing string at first. It may include several groups of characters, so don’t assume that every number printed on the back is the document number.

The document number is associated with the card itself. It appears in the first line near the bottom of the back.

A practical way to check it is to compare the characters with the format expected by the form:

Look for a group that includes letters and numbers.
Check the first line, not just the second or third line.
Keep the letters if the document number includes them.
Don’t replace the document number with the separate USCIS or A-Number.

Some forms call this the card number, while others call it the document number. If the field clearly asks for the document number on your Permanent Resident Card, the requested value is the one in the machine-readable area on the back.

Read the characters carefully. Letters and numbers can look similar, especially in a small printed line. If you’re typing the number into an online form, enter it exactly as shown and follow any instructions about spaces or punctuation.

What the document number looks like on current card designs

Current card designs are described as using a 13-character alphanumeric document number. “Alphanumeric” simply means the code can contain both letters and numbers.

You may also see the document number described as:

Three letters followed by 10 numbers
Three letters followed by 11 numbers
A 13-character code
A 13-digit document number

These descriptions don’t always match perfectly because card designs and explanations can differ. In particular, a code with three letters plus 10 or 11 numbers does not contain only digits. That’s why 13-character is often a clearer description than “13-digit” when letters appear in the code.

The main point is where to look and what kind of code to expect:

> Back of the card → bottom machine-readable zone → first line → document number

Don’t reject the number simply because your card doesn’t match one sample exactly. A different combination of letters and numbers may reflect a different card format.

Document number vs. USCIS number or A-Number

The green card document number and the USCIS number, also called the A-Number, are different numbers.

Both are connected to your immigration record, and both may appear on the back of the card. That’s why they’re easy to mix up when you’re completing a form.

Here’s the basic difference:

Number	What it identifies	Where to focus
Document number	The Permanent Resident Card itself	First line of the long machine-readable string near the bottom on the back
USCIS number / A-Number	Your immigration identification number	A separate number on the card, also identified on the back

If a form asks for your USCIS number or A-Number, use that number. If it asks for your document number, use the number in the first line of the machine-readable area.

The wording on the form matters more than the fact that both numbers are printed on the same card. Don’t enter the A-Number just because it’s a familiar nine-digit number.

What the 9-digit number on a Permanent Resident Card means

The nine-digit number on a Permanent Resident Card is treated separately from the document number. It is commonly associated with the USCIS number or A-Number shown on the card.

That means a form asking for a nine-digit USCIS number is not necessarily asking for the green card document number.

Use this quick comparison:

Document number: Found in the first line of the machine-readable zone on the back. It may contain letters and numbers.
USCIS number or A-Number: A separate immigration identification number on the card. It is commonly shown as nine digits.
Nine-digit number request: Follow the form’s wording. It may be asking for the USCIS/A-Number rather than the card’s document number.

Some forms use slightly different labels, so read the entire field carefully. “Document number,” “USCIS number,” “A-Number,” and “nine-digit number” should not be treated as interchangeable.

When in doubt, turn the card over again. The number’s location and the form’s exact wording are better guides than the number’s size alone.

Why different green card number formats may appear

You may find different examples of a green card document number because Permanent Resident Cards have had different designs and descriptions.

One explanation may call it a 13-digit number. Another may describe it as a code with three letters followed by 10 or 11 numbers. Current card descriptions may refer to a 13-character alphanumeric number.

Those labels can be confusing, especially if you’re trying to finish an employment or immigration form quickly. The safest approach is not to force your card into one example. Instead, check all three details:

Location: Is the number on the back?
Line: Is it in the first line of the long machine-readable string near the bottom?
Format: Does it contain the letters and numbers shown on your card?

A card that doesn’t match an online example exactly may still have the correct document number. Card design differences are one reason it’s risky to rely on a number’s format alone.

What to enter when a form asks for the document number

When a form asks for the green card document number, use the number from the first line of the machine-readable area on the back of your Permanent Resident Card.

Before submitting the form, check these points:

You turned the card over instead of relying on the front.
You looked near the bottom.
You used the first line of the long character string.
You included letters if the document number has them.
You did not substitute the USCIS number or A-Number.
You did not substitute a separate nine-digit number.
You followed the form’s instructions for spaces, hyphens, or other formatting.

If a form asks for more than one card detail, fill in each field separately. For example, a form might ask for the document number in one box and the USCIS number in another. The two fields are asking for different information.

The quickest safe check is simple: recheck the back of your card, find the document number in the first line near the bottom, and match that number’s label and location to the exact field your form requests.

Written by Ryan Mitchell

Ryan Mitchell is a U.S. visa consultant who helps individuals and families better understand the U.S. visa application process. He provides practical guidance on visa requirements, documentation, interview preparation, and common application questions, with a focus on making the process easier to understand.