I had a similar problem in CA: Both fed and state TT returns showed an amount for state tax that was higher than amount of state income tax withheld on my W-2. I was advised to check for additional state tax withholding in box 14 of w-2 and discovered the Ca State Disability Tax withholding. That explained the discrepancy.
Did you make any estimated tax payments in 2018 that don't show on w-2?
Did you owe any state tax for 2017 that you paid in 2018?
Any city inc tax or gross receipts tax?
