The DD number on a driver’s license is a serial number for the physical card, and you’ll usually find it printed on the front near the bottom or on the back next to the barcode. Depending on the state, it may be labeled “DD,” “Document No.,” “Doc No.,” “Audit No.,” “Audit Number,” or “Control Number.” It can be all digits or a mix of letters and numbers, and it may run up to 25 characters long.1American Association of Motor Vehicle Administrators. 2025 AAMVA DL/ID Card Design Standard
Where to Look on the Card
The national card design standard places the document discriminator in “Zone II,” which corresponds to the lower portion of the front of the card.1American Association of Motor Vehicle Administrators. 2025 AAMVA DL/ID Card Design Standard States have some flexibility in exactly where they print it, so check these spots in order:
- The front, bottom area, often below your license number or near your date of birth, usually in smaller type than the main fields.
- The back of the card, typically above or beside the PDF417 barcode strip.
- Inside a longer labeled string. A few states fold the DD into another number rather than giving it its own line.
If a field on your card holds a much longer string of characters than your license number, that is a strong clue you’re looking at the DD. Your state DMV’s website usually has a diagram labeling every field on the license, which is the fastest way to confirm.
What the DD Number Is
Your license carries two different numbers that do different jobs. Your license number stays with you for as long as you hold a license in that state. The DD number is tied to the physical card. Lose your license and get a replacement, and you’ll keep the same license number but receive a new DD. Renew at the end of your term, same thing: new card, new DD.
The technical name is “document discriminator,” and the national standard defines it as a number that “must uniquely identify a particular document issued to that customer from others that may have been issued in the past.”1American Association of Motor Vehicle Administrators. 2025 AAMVA DL/ID Card Design Standard If someone tried to use an old or counterfeit copy of your license, the DD number would flag the document as outdated or invalid when checked against the issuing agency’s records.
When You’ll Be Asked for It
The most common reason people go hunting for the DD number is tax season. A growing number of states ask for driver’s license information, including the document number, when you e-file a state income tax return. The field typically shows up as part of an identity verification step inside tax preparation software. If you leave it blank, some states still accept the return while others reject the electronic filing and force you to mail a paper return instead. Requirements vary, so check your state tax agency’s e-filing instructions if the software asks for a number you don’t recognize.
You may also run into the DD number when setting up an account on a government portal, registering for certain state services online, or completing financial applications that cross-reference your identity against DMV records. Some online voter registration systems ask for information from your license as part of the identity check, though most rely on your license number rather than the document discriminator.
One place the DD number is not required: employment verification on Form I-9. When your employer examines your driver’s license as a List B identity document, they need your name, photo, and basic identifying details like date of birth. The document discriminator isn’t part of that process.2USCIS. Form I-9 Acceptable Documents
When Your License May Not Show One
Temporary paper licenses, the kind you get at the counter while waiting for your permanent card in the mail, typically don’t include a document discriminator. The number is assigned to the physical card during production, so a printed interim document usually lacks it. If an online form requires a DD number and all you have is a temporary license, you may need to wait for your permanent card or contact the requesting agency about alternatives.
Older licenses issued before a state adopted the current AAMVA card design standard may not have a clearly labeled DD number either. If your card doesn’t show any of the common labels and you’ve had it for many years, it may predate your state’s adoption of the field. Renewing will get you a current-format card with the number included.
Some states use their own terminology that doesn’t map neatly to “DD.” If your card has a long alphanumeric string labeled something like “Inventory Control Number” or “ISS” followed by digits, that may serve the same function. Again, your state DMV’s field-by-field diagram is the quickest way to confirm which number a form is asking for.