TurboTax does not support the calculations for Code Z on Form W-2. You can use overrides in TurboTax desktop-CD/Download, you will just need to file your tax return by mail.
Please see the below answer from our Tax Support agent Rachel
Unfortunately, you will not be able to E-file your tax Return because TurboTax does not support the calculations for Code Z on Form W-2.
Check out the TurboTax FAQ below for more information:
https://ttlc.intuit.com/replies/3302281
