You can either skip that section and leave it blank. Or if you are receiving an error when trying to leave it blank, just put in any combination of numbers in this specific format 5 digits, space, 5 digits (for example, 12345 67890).
Leave out the letters, only input numbers in the specified format here.
That is just a number that the payroll team uses to identify your W-2 for their system purposes.This is not something the IRS needs, so as long as you input something in this format, you can proceed.
Like AndreaC1 mentioned in this post, a Control Number (box D) is used by many payroll departments to identify a W-2 in their system. If your W-2 doesn't have one, it's ok to leave it blank.
Please refer to the article below.
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