If you are asking what your control number is, the answer depends on the document in your hand. The phrase refers to a unique identifier printed on things like a W-2, a proxy voting card, a FAFSA Submission Summary, a passport application receipt, or a voter registration card. Each one lives in a different place and does a different job, so the first step is figuring out which document sent you looking.
W-2 Box D
Tax season is what drives most of these searches. 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 is an internal code your employer’s payroll system assigned 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 Many employers leave it blank. If yours is empty, nothing is wrong with the form.
Filing Taxes When Box D Is Blank
You can file without it. The IRS does not require anything in Box D for your return to be accepted. The numbers that actually matter are your employer’s EIN in Box B, your Social Security number in Box A, and the wage and withholding figures.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 your W-2 data from your employer’s payroll provider. That is convenient but not necessary. If the import fails or your W-2 doesn’t carry a control number, type your wage and tax figures in manually.
Proxy Voting Control Number
Shareholders in publicly traded companies receive proxy materials before shareholder meetings, and each set of materials includes a control number that acts as your voter credential. You need it to cast your vote online, by phone, or by mail.
The number typically appears on your proxy card or on the Notice of Internet Availability of Proxy Materials your broker sends. It is usually a 16-digit string printed prominently on the card, often near the top or in a section marked for your records. When you vote by phone, an automated system prompts you to enter it. When you vote online, the company’s voting website asks for it as the first step.2U.S. Securities and Exchange Commission. Spotlight on Proxy Matters – The Mechanics of Voting
If you hold shares through a brokerage, the control number often shows up in your online account under proxy voting or corporate actions.3Fidelity Institutional. Voting Proxy Help Every position you hold in a different company gets 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 identifier is the Data Release Number, or DRN. After you submit, the federal processor generates a DRN and prints it on the first page of your FAFSA Submission Summary. The number verifies your identity when you or a financial aid office needs to access your application.4Federal Student Aid. 2026-27 FAFSA Form
Two situations make the DRN matter. If you want to add colleges to your list after submitting, you give the DRN to the financial aid administrator at the school you want to add. And you need the DRN to review or make corrections to 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 appear 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. It ties your record to the state’s election database and helps poll workers verify your registration when you check in. The number is usually printed near your name and address on the card itself.
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 card at all. If you need yours and can’t find the card, contact your local election office or use your state’s voter registration lookup tool online. Most states offer one.
Recovering a Missing Control Number
The fix depends on which one you need:
- W-2 Box D: file without it. If your employer’s payroll system generated one that simply didn’t print, HR or payroll can look it up, but a blank Box D is no reason to delay filing.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 a representative or the online portal can retrieve it. Voting deadlines are firm.
- FAFSA DRN: log into 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.
Whichever document you’re dealing with, the organization that assigned the number is the fastest route to recovering it. Old emails, online account portals, and physical copies of correspondence are worth checking first.