I am having a similar problem for filing for 2018. Box 17 has UT followed by 9 numbers, and no 'WTH', which TT says it needs. Box 18 is not blank (it matches the amount in Box 7), but Box 16 (the state tax withheld) is $0.00. Based on the answer from TurboTaxDawnC, above, it sounds like I can just clear Boxes 16-18 since Box 16 indicates no state tax was withheld. Is this true?
