Does my employer need to provide a verification code on a W-2? This is Box 9. None of our W-2s have it, but TurboTax is flagging this as an error on one of my wife's W-2.

I've seen the IRS website and Intuit's response.

https://www.irs.gov/individuals/w-2-verification-code

https://ttlc.intuit.com/questions/4170713-when-i-try-to-e-file-box-9-comes-up-as-an-issue-that-needs...

However, I'm still not sure why SmartCheck is flagging this as an error when it seems to be optional.