Why does TurboTax require Box 'd' Control Number to import W2s if it is not required by the IRS and has no purpose in filing taxes?

[Anthony9]

Box 'd' Control Number on my W2 is blank/empty. I've come to learn by searching for help on this site that the IRS does not care about this field, nor does TurboTax really need it, as it's just an internal number some payroll departments use.

[macuser_22 · Accepted solution]

When you import a W-2 it is coming from a payroll company, not TurboTax and various payroll companies require the control number or other W-2 information for security purposes.

A control number is an option and not required. TurboTax does not require a control number.  The payroll company that some employers use might require it to verify that it is you and not an imposter trying to import your W-2.    Other payroll companies require other information from the W-2 to verify that.   Not all W-2's even have a control number since that is an employer option and not all employers make their W-2's available for import.  

[Anthony9]

That's a better breakdown that I previously found. Thank you!