Box D, the control number is not required to file your return, you can just leave it blank. If you are trying to import your W2 and don't have anything in Box D and if its required for import, you will have to manually enter your W2 instead.
See below for more information about how to enter a control number in TurboTax.
A Control Number (Box D) is used by many payroll departments to uniquely identify a W-2 in their system. If your W-2 doesn't have one, it's no big deal – you can simply leave it blank.
If you get errors when attempting to e-file with an empty Box D, just enter any number in this format: 5 digits, space, 5 digits (for example, 12345 67890). The IRS doesn't care what's in Box D because its use by payroll departments is optional.
On the other hand, if you're trying to import your W-2 and you are asked for a Control Box D, and you don’t have one, click skip import and then manually enter your W-2. You won't be able to import using the 5 digit + space + 5 digit solution for e-filing
