Get Answers Support Tax Filings & Payments W2 General What is the purpose of Box -D in Form W-2? Last modified 3/31/2023 4:53:59 AM EST Box D in Form W-2 is called the Control Number field. Control Number is a code that uniquely identifies your W-2 from the rest of the employer’s records. The control number is usually generated by your employee payroll software and is only necessary if you want to import your Form W-2 into the tax software electronically. It's important to note that the IRS does not mandate the reporting of the Control number in your Form W-2. Therefore, leaving out or filling in the Control number in your W-2 Form will not affect the accuracy of your reports. Was this helpful? Yes No Need more help? Get in touch with our dedicated support team Contact Us (704) 684-4751 support@taxbandits.com Sign Up for a FREE TaxBandits Account! The Smart CPA Choice Register Now Already have an account? Sign in