A control number is a unique code an organization prints on a document to identify that specific record within its system. The same term shows up in very different places: your W-2, proxy voting materials from companies you own stock in, your FAFSA submission, a passport application, and in some states your voter registration card. So the answer to “what is my control number” depends entirely on which document you’re holding.
W-2 Control Number in Box D
Tax season is the most common reason people go looking. On a W-2 Wage and Tax Statement, the control number sits in Box D, labeled “Control number,” between your employer’s information and your name and address. It’s an internal code assigned by your employer’s payroll system to your specific W-2. Formats vary by provider, so yours might be all digits, all letters, or a mix.
Box D is optional. The IRS instructions say employers “may use this box to identify individual Forms W-2” but “do not have to use this box.”1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3 – Section: Box d—Control number Plenty of employers leave it blank. A blank Box D does not mean anything is wrong with your W-2.
Can You File Taxes Without a W-2 Control Number?
Yes. The IRS does not require anything in Box D for your return to be accepted. The numbers that matter are your employer’s EIN in Box B, your Social Security number in Box A, and your wage and withholding figures. A missing control number has no effect on the accuracy of your filing.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3 – Section: Box d—Control number
Some tax software uses the control number to auto-import W-2 data from your employer’s payroll provider. That’s convenient, but it isn’t required. If the import fails or Box D is empty, enter the wage and tax information manually. The IRS ignores whatever is in that field.
Proxy Voting Control Number
If you own shares in a publicly traded company, you’ll get proxy materials before shareholder meetings. The packet includes a control number that works as your unique voter credential, and you need it to vote online, by phone, or by mail.
Look on your proxy card or on the Notice of Internet Availability of Proxy Materials your broker sends. The number is usually a 16-digit string printed near the top of the card or in a section marked for your records. When you vote by phone, the automated system prompts you to enter it. When you vote online, the voting website asks for it first.2U.S. Securities and Exchange Commission. Spotlight on Proxy Matters – The Mechanics of Voting
If you hold shares through a brokerage, the control number usually appears in your online account under proxy voting or corporate actions, and a separate security code may be required with it.3Fidelity Institutional. Voting Proxy Help Each position in a different company has its own number, so five companies holding meetings means five separate control numbers.
FAFSA Data Release Number
On the Free Application for Federal Student Aid, the equivalent is the Data Release Number, or DRN. The federal processor generates it after you submit, and it prints on the first page of your FAFSA Submission Summary. The DRN verifies your identity when you or a financial aid office needs to access your application.4Federal Student Aid. 2026-27 FAFSA Form
You’ll need the DRN in two situations. If you want to add a college to your list of schools receiving your FAFSA data after submission, you give the DRN to that school’s financial aid administrator. You also need it to review or correct your Student Aid Report online.
Passport Application Locator Number
When you apply for a U.S. passport, the Department of State assigns a nine-digit application locator number to track your submission.5Travel.State.Gov. Checking Your Application Status
You can find it by logging into the Online Passport Status System at travel.state.gov, which also shows where your application stands. If you applied in person at a passport agency, the locator number may be on the receipt you were given at your appointment.6Travel.State.Gov. Make an Appointment at a Passport Agency or Center
Voter Registration Number
Some states print a control number or voter ID number on your voter registration card to tie your record to the state’s election database and help poll workers verify your registration at check-in. The number is usually printed near your name and address.
Terminology and format vary. Some states call it a voter ID number, others a registration number, and some don’t print any unique identifier on the physical card. If you need it and can’t find your card, contact your local election office or use your state’s voter registration lookup tool online.
If You Can’t Find Your Control Number
The recovery path depends on the document:
- W-2 Box D: You can file without it. If you want the number anyway, your HR or payroll department can look it up.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3 – Section: Box d—Control number
- Proxy voting: Contact your brokerage. The number is tied to your account, and the online portal or a representative can retrieve it. Voting deadlines are firm, so don’t wait until the day of the meeting.
- FAFSA DRN: Log in at studentaid.gov to find it on your Submission Summary. If you can’t access your account, call Federal Student Aid at 1-800-433-3243.
- Passport locator number: Use the Online Passport Status System at travel.state.gov. You’ll need your last name, date of birth, and the last four digits of your Social Security number.5Travel.State.Gov. Checking Your Application Status
- Voter registration: Check your state’s online voter registration portal or call your county election office. Replacement cards are available in most states, though processing times vary.
For any document, the organization that issued the number is the fastest path to recovering it. Before you call, it’s worth searching old emails, checking online account portals, and looking through physical copies of the correspondence you were sent.